From d83be6df2d8b0e2fef4cb6866cfdb6434bbef5c4 Mon Sep 17 00:00:00 2001
From: hmhealey <harrisonmhealey@gmail.com>
Date: Thu, 17 Sep 2015 11:08:47 -0400
Subject: PLT-173 Added graphics-go and goexif libraries for image manipulation

---
 .../p/graphics-go/graphics/Makefile                |  15 ++
 .../p/graphics-go/graphics/affine.go               | 174 +++++++++++++
 .../code.google.com/p/graphics-go/graphics/blur.go |  68 +++++
 .../p/graphics-go/graphics/blur_test.go            | 207 ++++++++++++++++
 .../p/graphics-go/graphics/convolve/Makefile       |  11 +
 .../p/graphics-go/graphics/convolve/convolve.go    | 274 +++++++++++++++++++++
 .../graphics-go/graphics/convolve/convolve_test.go |  78 ++++++
 .../p/graphics-go/graphics/detect/Makefile         |  15 ++
 .../p/graphics-go/graphics/detect/detect.go        | 133 ++++++++++
 .../p/graphics-go/graphics/detect/detect_test.go   |  77 ++++++
 .../p/graphics-go/graphics/detect/doc.go           |  31 +++
 .../p/graphics-go/graphics/detect/integral.go      |  93 +++++++
 .../p/graphics-go/graphics/detect/integral_test.go | 156 ++++++++++++
 .../p/graphics-go/graphics/detect/opencv_parser.go | 125 ++++++++++
 .../graphics/detect/opencv_parser_test.go          |  75 ++++++
 .../p/graphics-go/graphics/detect/projector.go     |  55 +++++
 .../graphics-go/graphics/detect/projector_test.go  |  49 ++++
 .../p/graphics-go/graphics/graphicstest/Makefile   |  11 +
 .../graphics/graphicstest/graphicstest.go          | 112 +++++++++
 .../p/graphics-go/graphics/interp/Makefile         |  13 +
 .../p/graphics-go/graphics/interp/bilinear.go      | 206 ++++++++++++++++
 .../p/graphics-go/graphics/interp/bilinear_test.go | 143 +++++++++++
 .../p/graphics-go/graphics/interp/doc.go           |  25 ++
 .../p/graphics-go/graphics/interp/interp.go        |  29 +++
 .../p/graphics-go/graphics/rotate.go               |  35 +++
 .../p/graphics-go/graphics/rotate_test.go          | 169 +++++++++++++
 .../p/graphics-go/graphics/scale.go                |  31 +++
 .../p/graphics-go/graphics/scale_test.go           | 153 ++++++++++++
 .../p/graphics-go/graphics/shared_test.go          |  69 ++++++
 .../p/graphics-go/graphics/thumbnail.go            |  41 +++
 .../p/graphics-go/graphics/thumbnail_test.go       |  53 ++++
 31 files changed, 2726 insertions(+)
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/Makefile
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/affine.go
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/blur.go
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/blur_test.go
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/convolve/Makefile
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/convolve/convolve.go
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/convolve/convolve_test.go
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/Makefile
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/detect.go
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/detect_test.go
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/doc.go
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/integral.go
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/integral_test.go
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/opencv_parser.go
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/opencv_parser_test.go
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/projector.go
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/projector_test.go
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/graphicstest/Makefile
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/graphicstest/graphicstest.go
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/interp/Makefile
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/interp/bilinear.go
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/interp/bilinear_test.go
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/interp/doc.go
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/interp/interp.go
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/rotate.go
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/rotate_test.go
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/scale.go
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/scale_test.go
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/shared_test.go
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/thumbnail.go
 create mode 100644 Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/thumbnail_test.go

(limited to 'Godeps/_workspace/src/code.google.com/p/graphics-go/graphics')

diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/Makefile b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/Makefile
new file mode 100644
index 000000000..28a06f0e8
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/Makefile
@@ -0,0 +1,15 @@
+# Copyright 2011 The Graphics-Go Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+include $(GOROOT)/src/Make.inc
+
+TARG=code.google.com/p/graphics-go/graphics
+GOFILES=\
+	affine.go\
+	blur.go\
+	rotate.go\
+	scale.go\
+	thumbnail.go\
+
+include $(GOROOT)/src/Make.pkg
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/affine.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/affine.go
new file mode 100644
index 000000000..0ac2ec9da
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/affine.go
@@ -0,0 +1,174 @@
+// Copyright 2011 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package graphics
+
+import (
+	"code.google.com/p/graphics-go/graphics/interp"
+	"errors"
+	"image"
+	"image/draw"
+	"math"
+)
+
+// I is the identity Affine transform matrix.
+var I = Affine{
+	1, 0, 0,
+	0, 1, 0,
+	0, 0, 1,
+}
+
+// Affine is a 3x3 2D affine transform matrix.
+// M(i,j) is Affine[i*3+j].
+type Affine [9]float64
+
+// Mul returns the multiplication of two affine transform matrices.
+func (a Affine) Mul(b Affine) Affine {
+	return Affine{
+		a[0]*b[0] + a[1]*b[3] + a[2]*b[6],
+		a[0]*b[1] + a[1]*b[4] + a[2]*b[7],
+		a[0]*b[2] + a[1]*b[5] + a[2]*b[8],
+		a[3]*b[0] + a[4]*b[3] + a[5]*b[6],
+		a[3]*b[1] + a[4]*b[4] + a[5]*b[7],
+		a[3]*b[2] + a[4]*b[5] + a[5]*b[8],
+		a[6]*b[0] + a[7]*b[3] + a[8]*b[6],
+		a[6]*b[1] + a[7]*b[4] + a[8]*b[7],
+		a[6]*b[2] + a[7]*b[5] + a[8]*b[8],
+	}
+}
+
+func (a Affine) transformRGBA(dst *image.RGBA, src *image.RGBA, i interp.RGBA) error {
+	srcb := src.Bounds()
+	b := dst.Bounds()
+	for y := b.Min.Y; y < b.Max.Y; y++ {
+		for x := b.Min.X; x < b.Max.X; x++ {
+			sx, sy := a.pt(x, y)
+			if inBounds(srcb, sx, sy) {
+				c := i.RGBA(src, sx, sy)
+				off := (y-dst.Rect.Min.Y)*dst.Stride + (x-dst.Rect.Min.X)*4
+				dst.Pix[off+0] = c.R
+				dst.Pix[off+1] = c.G
+				dst.Pix[off+2] = c.B
+				dst.Pix[off+3] = c.A
+			}
+		}
+	}
+	return nil
+}
+
+// Transform applies the affine transform to src and produces dst.
+func (a Affine) Transform(dst draw.Image, src image.Image, i interp.Interp) error {
+	if dst == nil {
+		return errors.New("graphics: dst is nil")
+	}
+	if src == nil {
+		return errors.New("graphics: src is nil")
+	}
+
+	// RGBA fast path.
+	dstRGBA, dstOk := dst.(*image.RGBA)
+	srcRGBA, srcOk := src.(*image.RGBA)
+	interpRGBA, interpOk := i.(interp.RGBA)
+	if dstOk && srcOk && interpOk {
+		return a.transformRGBA(dstRGBA, srcRGBA, interpRGBA)
+	}
+
+	srcb := src.Bounds()
+	b := dst.Bounds()
+	for y := b.Min.Y; y < b.Max.Y; y++ {
+		for x := b.Min.X; x < b.Max.X; x++ {
+			sx, sy := a.pt(x, y)
+			if inBounds(srcb, sx, sy) {
+				dst.Set(x, y, i.Interp(src, sx, sy))
+			}
+		}
+	}
+	return nil
+}
+
+func inBounds(b image.Rectangle, x, y float64) bool {
+	if x < float64(b.Min.X) || x >= float64(b.Max.X) {
+		return false
+	}
+	if y < float64(b.Min.Y) || y >= float64(b.Max.Y) {
+		return false
+	}
+	return true
+}
+
+func (a Affine) pt(x0, y0 int) (x1, y1 float64) {
+	fx := float64(x0) + 0.5
+	fy := float64(y0) + 0.5
+	x1 = fx*a[0] + fy*a[1] + a[2]
+	y1 = fx*a[3] + fy*a[4] + a[5]
+	return x1, y1
+}
+
+// TransformCenter applies the affine transform to src and produces dst.
+// Equivalent to
+//   a.CenterFit(dst, src).Transform(dst, src, i).
+func (a Affine) TransformCenter(dst draw.Image, src image.Image, i interp.Interp) error {
+	if dst == nil {
+		return errors.New("graphics: dst is nil")
+	}
+	if src == nil {
+		return errors.New("graphics: src is nil")
+	}
+
+	return a.CenterFit(dst.Bounds(), src.Bounds()).Transform(dst, src, i)
+}
+
+// Scale produces a scaling transform of factors x and y.
+func (a Affine) Scale(x, y float64) Affine {
+	return a.Mul(Affine{
+		1 / x, 0, 0,
+		0, 1 / y, 0,
+		0, 0, 1,
+	})
+}
+
+// Rotate produces a clockwise rotation transform of angle, in radians.
+func (a Affine) Rotate(angle float64) Affine {
+	s, c := math.Sincos(angle)
+	return a.Mul(Affine{
+		+c, +s, +0,
+		-s, +c, +0,
+		+0, +0, +1,
+	})
+}
+
+// Shear produces a shear transform by the slopes x and y.
+func (a Affine) Shear(x, y float64) Affine {
+	d := 1 - x*y
+	return a.Mul(Affine{
+		+1 / d, -x / d, 0,
+		-y / d, +1 / d, 0,
+		0, 0, 1,
+	})
+}
+
+// Translate produces a translation transform with pixel distances x and y.
+func (a Affine) Translate(x, y float64) Affine {
+	return a.Mul(Affine{
+		1, 0, -x,
+		0, 1, -y,
+		0, 0, +1,
+	})
+}
+
+// Center produces the affine transform, centered around the provided point.
+func (a Affine) Center(x, y float64) Affine {
+	return I.Translate(-x, -y).Mul(a).Translate(x, y)
+}
+
+// CenterFit produces the affine transform, centered around the rectangles.
+// It is equivalent to
+//   I.Translate(-<center of src>).Mul(a).Translate(<center of dst>)
+func (a Affine) CenterFit(dst, src image.Rectangle) Affine {
+	dx := float64(dst.Min.X) + float64(dst.Dx())/2
+	dy := float64(dst.Min.Y) + float64(dst.Dy())/2
+	sx := float64(src.Min.X) + float64(src.Dx())/2
+	sy := float64(src.Min.Y) + float64(src.Dy())/2
+	return I.Translate(-sx, -sy).Mul(a).Translate(dx, dy)
+}
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/blur.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/blur.go
new file mode 100644
index 000000000..9a54d5ad5
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/blur.go
@@ -0,0 +1,68 @@
+// Copyright 2011 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package graphics
+
+import (
+	"code.google.com/p/graphics-go/graphics/convolve"
+	"errors"
+	"image"
+	"image/draw"
+	"math"
+)
+
+// DefaultStdDev is the default blurring parameter.
+var DefaultStdDev = 0.5
+
+// BlurOptions are the blurring parameters.
+// StdDev is the standard deviation of the normal, higher is blurrier.
+// Size is the size of the kernel. If zero, it is set to Ceil(6 * StdDev).
+type BlurOptions struct {
+	StdDev float64
+	Size   int
+}
+
+// Blur produces a blurred version of the image, using a Gaussian blur.
+func Blur(dst draw.Image, src image.Image, opt *BlurOptions) error {
+	if dst == nil {
+		return errors.New("graphics: dst is nil")
+	}
+	if src == nil {
+		return errors.New("graphics: src is nil")
+	}
+
+	sd := DefaultStdDev
+	size := 0
+
+	if opt != nil {
+		sd = opt.StdDev
+		size = opt.Size
+	}
+
+	if size < 1 {
+		size = int(math.Ceil(sd * 6))
+	}
+
+	kernel := make([]float64, 2*size+1)
+	for i := 0; i <= size; i++ {
+		x := float64(i) / sd
+		x = math.Pow(1/math.SqrtE, x*x)
+		kernel[size-i] = x
+		kernel[size+i] = x
+	}
+
+	// Normalize the weights to sum to 1.0.
+	kSum := 0.0
+	for _, k := range kernel {
+		kSum += k
+	}
+	for i, k := range kernel {
+		kernel[i] = k / kSum
+	}
+
+	return convolve.Convolve(dst, src, &convolve.SeparableKernel{
+		X: kernel,
+		Y: kernel,
+	})
+}
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/blur_test.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/blur_test.go
new file mode 100644
index 000000000..1d84fa604
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/blur_test.go
@@ -0,0 +1,207 @@
+// Copyright 2011 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package graphics
+
+import (
+	"code.google.com/p/graphics-go/graphics/graphicstest"
+	"image"
+	"image/color"
+	"testing"
+
+	_ "image/png"
+)
+
+var blurOneColorTests = []transformOneColorTest{
+	{
+		"1x1-blank", 1, 1, 1, 1,
+		&BlurOptions{0.83, 1},
+		[]uint8{0xff},
+		[]uint8{0xff},
+	},
+	{
+		"1x1-spreadblank", 1, 1, 1, 1,
+		&BlurOptions{0.83, 2},
+		[]uint8{0xff},
+		[]uint8{0xff},
+	},
+	{
+		"3x3-blank", 3, 3, 3, 3,
+		&BlurOptions{0.83, 2},
+		[]uint8{
+			0xff, 0xff, 0xff,
+			0xff, 0xff, 0xff,
+			0xff, 0xff, 0xff,
+		},
+		[]uint8{
+			0xff, 0xff, 0xff,
+			0xff, 0xff, 0xff,
+			0xff, 0xff, 0xff,
+		},
+	},
+	{
+		"3x3-dot", 3, 3, 3, 3,
+		&BlurOptions{0.34, 1},
+		[]uint8{
+			0x00, 0x00, 0x00,
+			0x00, 0xff, 0x00,
+			0x00, 0x00, 0x00,
+		},
+		[]uint8{
+			0x00, 0x03, 0x00,
+			0x03, 0xf2, 0x03,
+			0x00, 0x03, 0x00,
+		},
+	},
+	{
+		"5x5-dot", 5, 5, 5, 5,
+		&BlurOptions{0.34, 1},
+		[]uint8{
+			0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0xff, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00,
+		},
+		[]uint8{
+			0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x03, 0x00, 0x00,
+			0x00, 0x03, 0xf2, 0x03, 0x00,
+			0x00, 0x00, 0x03, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00,
+		},
+	},
+	{
+		"5x5-dot-spread", 5, 5, 5, 5,
+		&BlurOptions{0.85, 1},
+		[]uint8{
+			0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0xff, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00,
+		},
+		[]uint8{
+			0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x10, 0x20, 0x10, 0x00,
+			0x00, 0x20, 0x40, 0x20, 0x00,
+			0x00, 0x10, 0x20, 0x10, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00,
+		},
+	},
+	{
+		"4x4-box", 4, 4, 4, 4,
+		&BlurOptions{0.34, 1},
+		[]uint8{
+			0x00, 0x00, 0x00, 0x00,
+			0x00, 0xff, 0xff, 0x00,
+			0x00, 0xff, 0xff, 0x00,
+			0x00, 0x00, 0x00, 0x00,
+		},
+		[]uint8{
+			0x00, 0x03, 0x03, 0x00,
+			0x03, 0xf8, 0xf8, 0x03,
+			0x03, 0xf8, 0xf8, 0x03,
+			0x00, 0x03, 0x03, 0x00,
+		},
+	},
+	{
+		"5x5-twodots", 5, 5, 5, 5,
+		&BlurOptions{0.34, 1},
+		[]uint8{
+			0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x96, 0x00, 0x96, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00,
+		},
+		[]uint8{
+			0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x02, 0x00, 0x02, 0x00,
+			0x02, 0x8e, 0x04, 0x8e, 0x02,
+			0x00, 0x02, 0x00, 0x02, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00,
+		},
+	},
+}
+
+func TestBlurOneColor(t *testing.T) {
+	for _, oc := range blurOneColorTests {
+		dst := oc.newDst()
+		src := oc.newSrc()
+		opt := oc.opt.(*BlurOptions)
+		if err := Blur(dst, src, opt); err != nil {
+			t.Fatal(err)
+		}
+
+		if !checkTransformTest(t, &oc, dst) {
+			continue
+		}
+	}
+}
+
+func TestBlurEmpty(t *testing.T) {
+	empty := image.NewRGBA(image.Rect(0, 0, 0, 0))
+	if err := Blur(empty, empty, nil); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestBlurGopher(t *testing.T) {
+	src, err := graphicstest.LoadImage("../testdata/gopher.png")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	dst := image.NewRGBA(src.Bounds())
+	if err = Blur(dst, src, &BlurOptions{StdDev: 1.1}); err != nil {
+		t.Fatal(err)
+	}
+
+	cmp, err := graphicstest.LoadImage("../testdata/gopher-blur.png")
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = graphicstest.ImageWithinTolerance(dst, cmp, 0x101)
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func benchBlur(b *testing.B, bounds image.Rectangle) {
+	b.StopTimer()
+
+	// Construct a fuzzy image.
+	src := image.NewRGBA(bounds)
+	for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+		for x := bounds.Min.X; x < bounds.Max.X; x++ {
+			src.SetRGBA(x, y, color.RGBA{
+				uint8(5 * x % 0x100),
+				uint8(7 * y % 0x100),
+				uint8((7*x + 5*y) % 0x100),
+				0xff,
+			})
+		}
+	}
+	dst := image.NewRGBA(bounds)
+
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		Blur(dst, src, &BlurOptions{0.84, 3})
+	}
+}
+
+func BenchmarkBlur400x400x3(b *testing.B) {
+	benchBlur(b, image.Rect(0, 0, 400, 400))
+}
+
+// Exactly twice the pixel count of 400x400.
+func BenchmarkBlur400x800x3(b *testing.B) {
+	benchBlur(b, image.Rect(0, 0, 400, 800))
+}
+
+// Exactly twice the pixel count of 400x800
+func BenchmarkBlur400x1600x3(b *testing.B) {
+	benchBlur(b, image.Rect(0, 0, 400, 1600))
+}
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/convolve/Makefile b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/convolve/Makefile
new file mode 100644
index 000000000..a5691fa30
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/convolve/Makefile
@@ -0,0 +1,11 @@
+# Copyright 2011 The Graphics-Go Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+include $(GOROOT)/src/Make.inc
+
+TARG=code.google.com/p/graphics-go/graphics/convolve
+GOFILES=\
+	convolve.go\
+
+include $(GOROOT)/src/Make.pkg
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/convolve/convolve.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/convolve/convolve.go
new file mode 100644
index 000000000..da69496d0
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/convolve/convolve.go
@@ -0,0 +1,274 @@
+// Copyright 2011 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package convolve
+
+import (
+	"errors"
+	"fmt"
+	"image"
+	"image/draw"
+	"math"
+)
+
+// clamp clamps x to the range [x0, x1].
+func clamp(x, x0, x1 float64) float64 {
+	if x < x0 {
+		return x0
+	}
+	if x > x1 {
+		return x1
+	}
+	return x
+}
+
+// Kernel is a square matrix that defines a convolution.
+type Kernel interface {
+	// Weights returns the square matrix of weights in row major order.
+	Weights() []float64
+}
+
+// SeparableKernel is a linearly separable, square convolution kernel.
+// X and Y are the per-axis weights. Each slice must be the same length, and
+// have an odd length. The middle element of each slice is the weight for the
+// central pixel. For example, the horizontal Sobel kernel is:
+//	sobelX := &SeparableKernel{
+//		X: []float64{-1, 0, +1},
+//		Y: []float64{1, 2, 1},
+//	}
+type SeparableKernel struct {
+	X, Y []float64
+}
+
+func (k *SeparableKernel) Weights() []float64 {
+	n := len(k.X)
+	w := make([]float64, n*n)
+	for y := 0; y < n; y++ {
+		for x := 0; x < n; x++ {
+			w[y*n+x] = k.X[x] * k.Y[y]
+		}
+	}
+	return w
+}
+
+// fullKernel is a square convolution kernel.
+type fullKernel []float64
+
+func (k fullKernel) Weights() []float64 { return k }
+
+func kernelSize(w []float64) (size int, err error) {
+	size = int(math.Sqrt(float64(len(w))))
+	if size*size != len(w) {
+		return 0, errors.New("graphics: kernel is not square")
+	}
+	if size%2 != 1 {
+		return 0, errors.New("graphics: kernel size is not odd")
+	}
+	return size, nil
+}
+
+// NewKernel returns a square convolution kernel.
+func NewKernel(w []float64) (Kernel, error) {
+	if _, err := kernelSize(w); err != nil {
+		return nil, err
+	}
+	return fullKernel(w), nil
+}
+
+func convolveRGBASep(dst *image.RGBA, src image.Image, k *SeparableKernel) error {
+	if len(k.X) != len(k.Y) {
+		return fmt.Errorf("graphics: kernel not square (x %d, y %d)", len(k.X), len(k.Y))
+	}
+	if len(k.X)%2 != 1 {
+		return fmt.Errorf("graphics: kernel length (%d) not odd", len(k.X))
+	}
+	radius := (len(k.X) - 1) / 2
+
+	// buf holds the result of vertically blurring src.
+	bounds := dst.Bounds()
+	width, height := bounds.Dx(), bounds.Dy()
+	buf := make([]float64, width*height*4)
+	for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+		for x := bounds.Min.X; x < bounds.Max.X; x++ {
+			var r, g, b, a float64
+			// k0 is the kernel weight for the center pixel. This may be greater
+			// than kernel[0], near the boundary of the source image, to avoid
+			// vignetting.
+			k0 := k.X[radius]
+
+			// Add the pixels from above.
+			for i := 1; i <= radius; i++ {
+				f := k.Y[radius-i]
+				if y-i < bounds.Min.Y {
+					k0 += f
+				} else {
+					or, og, ob, oa := src.At(x, y-i).RGBA()
+					r += float64(or>>8) * f
+					g += float64(og>>8) * f
+					b += float64(ob>>8) * f
+					a += float64(oa>>8) * f
+				}
+			}
+
+			// Add the pixels from below.
+			for i := 1; i <= radius; i++ {
+				f := k.Y[radius+i]
+				if y+i >= bounds.Max.Y {
+					k0 += f
+				} else {
+					or, og, ob, oa := src.At(x, y+i).RGBA()
+					r += float64(or>>8) * f
+					g += float64(og>>8) * f
+					b += float64(ob>>8) * f
+					a += float64(oa>>8) * f
+				}
+			}
+
+			// Add the central pixel.
+			or, og, ob, oa := src.At(x, y).RGBA()
+			r += float64(or>>8) * k0
+			g += float64(og>>8) * k0
+			b += float64(ob>>8) * k0
+			a += float64(oa>>8) * k0
+
+			// Write to buf.
+			o := (y-bounds.Min.Y)*width*4 + (x-bounds.Min.X)*4
+			buf[o+0] = r
+			buf[o+1] = g
+			buf[o+2] = b
+			buf[o+3] = a
+		}
+	}
+
+	// dst holds the result of horizontally blurring buf.
+	for y := 0; y < height; y++ {
+		for x := 0; x < width; x++ {
+			var r, g, b, a float64
+			k0, off := k.X[radius], y*width*4+x*4
+
+			// Add the pixels from the left.
+			for i := 1; i <= radius; i++ {
+				f := k.X[radius-i]
+				if x-i < 0 {
+					k0 += f
+				} else {
+					o := off - i*4
+					r += buf[o+0] * f
+					g += buf[o+1] * f
+					b += buf[o+2] * f
+					a += buf[o+3] * f
+				}
+			}
+
+			// Add the pixels from the right.
+			for i := 1; i <= radius; i++ {
+				f := k.X[radius+i]
+				if x+i >= width {
+					k0 += f
+				} else {
+					o := off + i*4
+					r += buf[o+0] * f
+					g += buf[o+1] * f
+					b += buf[o+2] * f
+					a += buf[o+3] * f
+				}
+			}
+
+			// Add the central pixel.
+			r += buf[off+0] * k0
+			g += buf[off+1] * k0
+			b += buf[off+2] * k0
+			a += buf[off+3] * k0
+
+			// Write to dst, clamping to the range [0, 255].
+			dstOff := (y-dst.Rect.Min.Y)*dst.Stride + (x-dst.Rect.Min.X)*4
+			dst.Pix[dstOff+0] = uint8(clamp(r+0.5, 0, 255))
+			dst.Pix[dstOff+1] = uint8(clamp(g+0.5, 0, 255))
+			dst.Pix[dstOff+2] = uint8(clamp(b+0.5, 0, 255))
+			dst.Pix[dstOff+3] = uint8(clamp(a+0.5, 0, 255))
+		}
+	}
+
+	return nil
+}
+
+func convolveRGBA(dst *image.RGBA, src image.Image, k Kernel) error {
+	b := dst.Bounds()
+	bs := src.Bounds()
+	w := k.Weights()
+	size, err := kernelSize(w)
+	if err != nil {
+		return err
+	}
+	radius := (size - 1) / 2
+
+	for y := b.Min.Y; y < b.Max.Y; y++ {
+		for x := b.Min.X; x < b.Max.X; x++ {
+			if !image.Pt(x, y).In(bs) {
+				continue
+			}
+
+			var r, g, b, a, adj float64
+			for cy := y - radius; cy <= y+radius; cy++ {
+				for cx := x - radius; cx <= x+radius; cx++ {
+					factor := w[(cy-y+radius)*size+cx-x+radius]
+					if !image.Pt(cx, cy).In(bs) {
+						adj += factor
+					} else {
+						sr, sg, sb, sa := src.At(cx, cy).RGBA()
+						r += float64(sr>>8) * factor
+						g += float64(sg>>8) * factor
+						b += float64(sb>>8) * factor
+						a += float64(sa>>8) * factor
+					}
+				}
+			}
+
+			if adj != 0 {
+				sr, sg, sb, sa := src.At(x, y).RGBA()
+				r += float64(sr>>8) * adj
+				g += float64(sg>>8) * adj
+				b += float64(sb>>8) * adj
+				a += float64(sa>>8) * adj
+			}
+
+			off := (y-dst.Rect.Min.Y)*dst.Stride + (x-dst.Rect.Min.X)*4
+			dst.Pix[off+0] = uint8(clamp(r+0.5, 0, 0xff))
+			dst.Pix[off+1] = uint8(clamp(g+0.5, 0, 0xff))
+			dst.Pix[off+2] = uint8(clamp(b+0.5, 0, 0xff))
+			dst.Pix[off+3] = uint8(clamp(a+0.5, 0, 0xff))
+		}
+	}
+
+	return nil
+}
+
+// Convolve produces dst by applying the convolution kernel k to src.
+func Convolve(dst draw.Image, src image.Image, k Kernel) (err error) {
+	if dst == nil || src == nil || k == nil {
+		return nil
+	}
+
+	b := dst.Bounds()
+	dstRgba, ok := dst.(*image.RGBA)
+	if !ok {
+		dstRgba = image.NewRGBA(b)
+	}
+
+	switch k := k.(type) {
+	case *SeparableKernel:
+		err = convolveRGBASep(dstRgba, src, k)
+	default:
+		err = convolveRGBA(dstRgba, src, k)
+	}
+
+	if err != nil {
+		return err
+	}
+
+	if !ok {
+		draw.Draw(dst, b, dstRgba, b.Min, draw.Src)
+	}
+	return nil
+}
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/convolve/convolve_test.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/convolve/convolve_test.go
new file mode 100644
index 000000000..f34d7afc8
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/convolve/convolve_test.go
@@ -0,0 +1,78 @@
+// Copyright 2011 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package convolve
+
+import (
+	"code.google.com/p/graphics-go/graphics/graphicstest"
+	"image"
+	"reflect"
+	"testing"
+
+	_ "image/png"
+)
+
+func TestSeparableWeights(t *testing.T) {
+	sobelXFull := []float64{
+		-1, 0, 1,
+		-2, 0, 2,
+		-1, 0, 1,
+	}
+	sobelXSep := &SeparableKernel{
+		X: []float64{-1, 0, +1},
+		Y: []float64{1, 2, 1},
+	}
+	w := sobelXSep.Weights()
+	if !reflect.DeepEqual(w, sobelXFull) {
+		t.Errorf("got %v want %v", w, sobelXFull)
+	}
+}
+
+func TestConvolve(t *testing.T) {
+	kernFull, err := NewKernel([]float64{
+		0, 0, 0,
+		1, 1, 1,
+		0, 0, 0,
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	kernSep := &SeparableKernel{
+		X: []float64{1, 1, 1},
+		Y: []float64{0, 1, 0},
+	}
+
+	src, err := graphicstest.LoadImage("../../testdata/gopher.png")
+	if err != nil {
+		t.Fatal(err)
+	}
+	b := src.Bounds()
+
+	sep := image.NewRGBA(b)
+	if err = Convolve(sep, src, kernSep); err != nil {
+		t.Fatal(err)
+	}
+
+	full := image.NewRGBA(b)
+	Convolve(full, src, kernFull)
+
+	err = graphicstest.ImageWithinTolerance(sep, full, 0x101)
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestConvolveNil(t *testing.T) {
+	if err := Convolve(nil, nil, nil); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestConvolveEmpty(t *testing.T) {
+	empty := image.NewRGBA(image.Rect(0, 0, 0, 0))
+	if err := Convolve(empty, empty, nil); err != nil {
+		t.Fatal(err)
+	}
+}
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/Makefile b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/Makefile
new file mode 100644
index 000000000..0b1c6cb3e
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/Makefile
@@ -0,0 +1,15 @@
+# Copyright 2011 The Graphics-Go Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+include $(GOROOT)/src/Make.inc
+
+TARG=code.google.com/p/graphics-go/graphics
+GOFILES=\
+	detect.go\
+	doc.go\
+	integral.go\
+	opencv_parser.go\
+	projector.go\
+
+include $(GOROOT)/src/Make.pkg
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/detect.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/detect.go
new file mode 100644
index 000000000..dde941cbe
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/detect.go
@@ -0,0 +1,133 @@
+// Copyright 2011 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package detect
+
+import (
+	"image"
+	"math"
+)
+
+// Feature is a Haar-like feature.
+type Feature struct {
+	Rect   image.Rectangle
+	Weight float64
+}
+
+// Classifier is a set of features with a threshold.
+type Classifier struct {
+	Feature   []Feature
+	Threshold float64
+	Left      float64
+	Right     float64
+}
+
+// CascadeStage is a cascade of classifiers.
+type CascadeStage struct {
+	Classifier []Classifier
+	Threshold  float64
+}
+
+// Cascade is a degenerate tree of Haar-like classifiers.
+type Cascade struct {
+	Stage []CascadeStage
+	Size  image.Point
+}
+
+// Match returns true if the full image is classified as an object.
+func (c *Cascade) Match(m image.Image) bool {
+	return c.classify(newWindow(m))
+}
+
+// Find returns a set of areas of m that match the feature cascade c.
+func (c *Cascade) Find(m image.Image) []image.Rectangle {
+	// TODO(crawshaw): Consider de-duping strategies.
+	matches := []image.Rectangle{}
+	w := newWindow(m)
+
+	b := m.Bounds()
+	origScale := c.Size
+	for s := origScale; s.X < b.Dx() && s.Y < b.Dy(); s = s.Add(s.Div(10)) {
+		// translate region and classify
+		tx := image.Pt(s.X/10, 0)
+		ty := image.Pt(0, s.Y/10)
+		for r := image.Rect(0, 0, s.X, s.Y).Add(b.Min); r.In(b); r = r.Add(ty) {
+			for r1 := r; r1.In(b); r1 = r1.Add(tx) {
+				if c.classify(w.subWindow(r1)) {
+					matches = append(matches, r1)
+				}
+			}
+		}
+	}
+	return matches
+}
+
+type window struct {
+	mi      *integral
+	miSq    *integral
+	rect    image.Rectangle
+	invArea float64
+	stdDev  float64
+}
+
+func (w *window) init() {
+	w.invArea = 1 / float64(w.rect.Dx()*w.rect.Dy())
+	mean := float64(w.mi.sum(w.rect)) * w.invArea
+	vr := float64(w.miSq.sum(w.rect))*w.invArea - mean*mean
+	if vr < 0 {
+		vr = 1
+	}
+	w.stdDev = math.Sqrt(vr)
+}
+
+func newWindow(m image.Image) *window {
+	mi, miSq := newIntegrals(m)
+	res := &window{
+		mi:   mi,
+		miSq: miSq,
+		rect: m.Bounds(),
+	}
+	res.init()
+	return res
+}
+
+func (w *window) subWindow(r image.Rectangle) *window {
+	res := &window{
+		mi:   w.mi,
+		miSq: w.miSq,
+		rect: r,
+	}
+	res.init()
+	return res
+}
+
+func (c *Classifier) classify(w *window, pr *projector) float64 {
+	s := 0.0
+	for _, f := range c.Feature {
+		s += float64(w.mi.sum(pr.rect(f.Rect))) * f.Weight
+	}
+	s *= w.invArea // normalize to maintain scale invariance
+	if s < c.Threshold*w.stdDev {
+		return c.Left
+	}
+	return c.Right
+}
+
+func (s *CascadeStage) classify(w *window, pr *projector) bool {
+	sum := 0.0
+	for _, c := range s.Classifier {
+		sum += c.classify(w, pr)
+	}
+	return sum >= s.Threshold
+}
+
+func (c *Cascade) classify(w *window) bool {
+	pr := newProjector(w.rect, image.Rectangle{image.Pt(0, 0), c.Size})
+	for _, s := range c.Stage {
+		if !s.classify(w, pr) {
+			return false
+		}
+	}
+	return true
+}
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/detect_test.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/detect_test.go
new file mode 100644
index 000000000..8a2df113d
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/detect_test.go
@@ -0,0 +1,77 @@
+// Copyright 2011 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package detect
+
+import (
+	"image"
+	"image/draw"
+	"testing"
+)
+
+var (
+	c0 = Classifier{
+		Feature: []Feature{
+			Feature{Rect: image.Rect(0, 0, 3, 4), Weight: 4.0},
+		},
+		Threshold: 0.2,
+		Left:      0.8,
+		Right:     0.2,
+	}
+	c1 = Classifier{
+		Feature: []Feature{
+			Feature{Rect: image.Rect(3, 4, 4, 5), Weight: 4.0},
+		},
+		Threshold: 0.2,
+		Left:      0.8,
+		Right:     0.2,
+	}
+	c2 = Classifier{
+		Feature: []Feature{
+			Feature{Rect: image.Rect(0, 0, 1, 1), Weight: +4.0},
+			Feature{Rect: image.Rect(0, 0, 2, 2), Weight: -1.0},
+		},
+		Threshold: 0.2,
+		Left:      0.8,
+		Right:     0.2,
+	}
+)
+
+func TestClassifier(t *testing.T) {
+	m := image.NewGray(image.Rect(0, 0, 20, 20))
+	b := m.Bounds()
+	draw.Draw(m, image.Rect(0, 0, 20, 20), image.White, image.ZP, draw.Src)
+	draw.Draw(m, image.Rect(3, 4, 4, 5), image.Black, image.ZP, draw.Src)
+	w := newWindow(m)
+	pr := newProjector(b, b)
+
+	if res := c0.classify(w, pr); res != c0.Right {
+		t.Errorf("c0 got %f want %f", res, c0.Right)
+	}
+	if res := c1.classify(w, pr); res != c1.Left {
+		t.Errorf("c1 got %f want %f", res, c1.Left)
+	}
+	if res := c2.classify(w, pr); res != c1.Left {
+		t.Errorf("c2 got %f want %f", res, c1.Left)
+	}
+}
+
+func TestClassifierScale(t *testing.T) {
+	m := image.NewGray(image.Rect(0, 0, 50, 50))
+	b := m.Bounds()
+	draw.Draw(m, image.Rect(0, 0, 8, 10), image.White, b.Min, draw.Src)
+	draw.Draw(m, image.Rect(8, 10, 10, 13), image.Black, b.Min, draw.Src)
+	w := newWindow(m)
+	pr := newProjector(b, image.Rect(0, 0, 20, 20))
+
+	if res := c0.classify(w, pr); res != c0.Right {
+		t.Errorf("scaled c0 got %f want %f", res, c0.Right)
+	}
+	if res := c1.classify(w, pr); res != c1.Left {
+		t.Errorf("scaled c1 got %f want %f", res, c1.Left)
+	}
+	if res := c2.classify(w, pr); res != c1.Left {
+		t.Errorf("scaled c2 got %f want %f", res, c1.Left)
+	}
+}
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/doc.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/doc.go
new file mode 100644
index 000000000..a0f4e94cd
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/doc.go
@@ -0,0 +1,31 @@
+// Copyright 2011 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+Package detect implements an object detector cascade.
+
+The technique used is a degenerate tree of Haar-like classifiers, commonly
+used for face detection. It is described in
+
+	P. Viola, M. Jones.
+	Rapid Object Detection using a Boosted Cascade of Simple Features, 2001
+	IEEE Conference on Computer Vision and Pattern Recognition
+
+A Cascade can be constructed manually from a set of Classifiers in stages,
+or can be loaded from an XML file in the OpenCV format with
+
+	classifier, _, err := detect.ParseOpenCV(r)
+
+The classifier can be used to determine if a full image is detected as an
+object using Detect
+
+	if classifier.Match(m) {
+		// m is an image of a face.
+	}
+
+It is also possible to search an image for occurrences of an object
+
+	objs := classifier.Find(m)
+*/
+package detect
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/integral.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/integral.go
new file mode 100644
index 000000000..814ced590
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/integral.go
@@ -0,0 +1,93 @@
+// Copyright 2011 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package detect
+
+import (
+	"image"
+	"image/draw"
+)
+
+// integral is an image.Image-like structure that stores the cumulative
+// sum of the preceding pixels. This allows for O(1) summation of any
+// rectangular region within the image.
+type integral struct {
+	// pix holds the cumulative sum of the image's pixels. The pixel at
+	// (x, y) starts at pix[(y-rect.Min.Y)*stride + (x-rect.Min.X)*1].
+	pix    []uint64
+	stride int
+	rect   image.Rectangle
+}
+
+func (p *integral) at(x, y int) uint64 {
+	return p.pix[(y-p.rect.Min.Y)*p.stride+(x-p.rect.Min.X)]
+}
+
+func (p *integral) sum(b image.Rectangle) uint64 {
+	c := p.at(b.Max.X-1, b.Max.Y-1)
+	inY := b.Min.Y > p.rect.Min.Y
+	inX := b.Min.X > p.rect.Min.X
+	if inY && inX {
+		c += p.at(b.Min.X-1, b.Min.Y-1)
+	}
+	if inY {
+		c -= p.at(b.Max.X-1, b.Min.Y-1)
+	}
+	if inX {
+		c -= p.at(b.Min.X-1, b.Max.Y-1)
+	}
+	return c
+}
+
+func (m *integral) integrate() {
+	b := m.rect
+	for y := b.Min.Y; y < b.Max.Y; y++ {
+		for x := b.Min.X; x < b.Max.X; x++ {
+			c := uint64(0)
+			if y > b.Min.Y && x > b.Min.X {
+				c += m.at(x-1, y)
+				c += m.at(x, y-1)
+				c -= m.at(x-1, y-1)
+			} else if y > b.Min.Y {
+				c += m.at(b.Min.X, y-1)
+			} else if x > b.Min.X {
+				c += m.at(x-1, b.Min.Y)
+			}
+			m.pix[(y-m.rect.Min.Y)*m.stride+(x-m.rect.Min.X)] += c
+		}
+	}
+}
+
+// newIntegrals returns the integral and the squared integral.
+func newIntegrals(src image.Image) (*integral, *integral) {
+	b := src.Bounds()
+	srcg, ok := src.(*image.Gray)
+	if !ok {
+		srcg = image.NewGray(b)
+		draw.Draw(srcg, b, src, b.Min, draw.Src)
+	}
+
+	m := integral{
+		pix:    make([]uint64, b.Max.Y*b.Max.X),
+		stride: b.Max.X,
+		rect:   b,
+	}
+	mSq := integral{
+		pix:    make([]uint64, b.Max.Y*b.Max.X),
+		stride: b.Max.X,
+		rect:   b,
+	}
+	for y := b.Min.Y; y < b.Max.Y; y++ {
+		for x := b.Min.X; x < b.Max.X; x++ {
+			os := (y-b.Min.Y)*srcg.Stride + x - b.Min.X
+			om := (y-b.Min.Y)*m.stride + x - b.Min.X
+			c := uint64(srcg.Pix[os])
+			m.pix[om] = c
+			mSq.pix[om] = c * c
+		}
+	}
+	m.integrate()
+	mSq.integrate()
+	return &m, &mSq
+}
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/integral_test.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/integral_test.go
new file mode 100644
index 000000000..0bc321a4d
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/integral_test.go
@@ -0,0 +1,156 @@
+// Copyright 2011 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package detect
+
+import (
+	"bytes"
+	"fmt"
+	"image"
+	"testing"
+)
+
+type integralTest struct {
+	x   int
+	y   int
+	src []uint8
+	res []uint8
+}
+
+var integralTests = []integralTest{
+	{
+		1, 1,
+		[]uint8{0x01},
+		[]uint8{0x01},
+	},
+	{
+		2, 2,
+		[]uint8{
+			0x01, 0x02,
+			0x03, 0x04,
+		},
+		[]uint8{
+			0x01, 0x03,
+			0x04, 0x0a,
+		},
+	},
+	{
+		4, 4,
+		[]uint8{
+			0x02, 0x03, 0x00, 0x01,
+			0x01, 0x02, 0x01, 0x05,
+			0x01, 0x01, 0x01, 0x01,
+			0x01, 0x01, 0x01, 0x01,
+		},
+		[]uint8{
+			0x02, 0x05, 0x05, 0x06,
+			0x03, 0x08, 0x09, 0x0f,
+			0x04, 0x0a, 0x0c, 0x13,
+			0x05, 0x0c, 0x0f, 0x17,
+		},
+	},
+}
+
+func sprintBox(box []byte, width, height int) string {
+	buf := bytes.NewBuffer(nil)
+	i := 0
+	for y := 0; y < height; y++ {
+		for x := 0; x < width; x++ {
+			fmt.Fprintf(buf, " 0x%02x,", box[i])
+			i++
+		}
+		buf.WriteByte('\n')
+	}
+	return buf.String()
+}
+
+func TestIntegral(t *testing.T) {
+	for i, oc := range integralTests {
+		src := &image.Gray{
+			Pix:    oc.src,
+			Stride: oc.x,
+			Rect:   image.Rect(0, 0, oc.x, oc.y),
+		}
+		dst, _ := newIntegrals(src)
+		res := make([]byte, len(dst.pix))
+		for i, p := range dst.pix {
+			res[i] = byte(p)
+		}
+
+		if !bytes.Equal(res, oc.res) {
+			got := sprintBox(res, oc.x, oc.y)
+			want := sprintBox(oc.res, oc.x, oc.y)
+			t.Errorf("%d: got\n%s\n want\n%s", i, got, want)
+		}
+	}
+}
+
+func TestIntegralSum(t *testing.T) {
+	src := &image.Gray{
+		Pix: []uint8{
+			0x02, 0x03, 0x00, 0x01, 0x03,
+			0x01, 0x02, 0x01, 0x05, 0x05,
+			0x01, 0x01, 0x01, 0x01, 0x02,
+			0x01, 0x01, 0x01, 0x01, 0x07,
+			0x02, 0x01, 0x00, 0x03, 0x01,
+		},
+		Stride: 5,
+		Rect:   image.Rect(0, 0, 5, 5),
+	}
+	img, _ := newIntegrals(src)
+
+	type sumTest struct {
+		rect image.Rectangle
+		sum  uint64
+	}
+
+	var sumTests = []sumTest{
+		{image.Rect(0, 0, 1, 1), 2},
+		{image.Rect(0, 0, 2, 1), 5},
+		{image.Rect(0, 0, 1, 3), 4},
+		{image.Rect(1, 1, 3, 3), 5},
+		{image.Rect(2, 2, 4, 4), 4},
+		{image.Rect(4, 3, 5, 5), 8},
+		{image.Rect(2, 4, 3, 5), 0},
+	}
+
+	for _, st := range sumTests {
+		s := img.sum(st.rect)
+		if s != st.sum {
+			t.Errorf("%v: got %d want %d", st.rect, s, st.sum)
+			return
+		}
+	}
+}
+
+func TestIntegralSubImage(t *testing.T) {
+	m0 := &image.Gray{
+		Pix: []uint8{
+			0x02, 0x03, 0x00, 0x01, 0x03,
+			0x01, 0x02, 0x01, 0x05, 0x05,
+			0x01, 0x04, 0x01, 0x01, 0x02,
+			0x01, 0x02, 0x01, 0x01, 0x07,
+			0x02, 0x01, 0x09, 0x03, 0x01,
+		},
+		Stride: 5,
+		Rect:   image.Rect(0, 0, 5, 5),
+	}
+	b := image.Rect(1, 1, 4, 4)
+	m1 := m0.SubImage(b)
+	mi0, _ := newIntegrals(m0)
+	mi1, _ := newIntegrals(m1)
+
+	sum0 := mi0.sum(b)
+	sum1 := mi1.sum(b)
+	if sum0 != sum1 {
+		t.Errorf("b got %d want %d", sum0, sum1)
+	}
+
+	r0 := image.Rect(2, 2, 4, 4)
+	sum0 = mi0.sum(r0)
+	sum1 = mi1.sum(r0)
+	if sum0 != sum1 {
+		t.Errorf("r0 got %d want %d", sum1, sum0)
+	}
+}
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/opencv_parser.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/opencv_parser.go
new file mode 100644
index 000000000..51ded1a1c
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/opencv_parser.go
@@ -0,0 +1,125 @@
+// Copyright 2011 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package detect
+
+import (
+	"bytes"
+	"encoding/xml"
+	"errors"
+	"fmt"
+	"image"
+	"io"
+	"io/ioutil"
+	"strconv"
+	"strings"
+)
+
+type xmlFeature struct {
+	Rects     []string `xml:"grp>feature>rects>grp"`
+	Tilted    int      `xml:"grp>feature>tilted"`
+	Threshold float64  `xml:"grp>threshold"`
+	Left      float64  `xml:"grp>left_val"`
+	Right     float64  `xml:"grp>right_val"`
+}
+
+type xmlStages struct {
+	Trees           []xmlFeature `xml:"trees>grp"`
+	Stage_threshold float64      `xml:"stage_threshold"`
+	Parent          int          `xml:"parent"`
+	Next            int          `xml:"next"`
+}
+
+type opencv_storage struct {
+	Any struct {
+		XMLName xml.Name
+		Type    string      `xml:"type_id,attr"`
+		Size    string      `xml:"size"`
+		Stages  []xmlStages `xml:"stages>grp"`
+	} `xml:",any"`
+}
+
+func buildFeature(r string) (f Feature, err error) {
+	var x, y, w, h int
+	var weight float64
+	_, err = fmt.Sscanf(r, "%d %d %d %d %f", &x, &y, &w, &h, &weight)
+	if err != nil {
+		return
+	}
+	f.Rect = image.Rect(x, y, x+w, y+h)
+	f.Weight = weight
+	return
+}
+
+func buildCascade(s *opencv_storage) (c *Cascade, name string, err error) {
+	if s.Any.Type != "opencv-haar-classifier" {
+		err = fmt.Errorf("got %s want opencv-haar-classifier", s.Any.Type)
+		return
+	}
+	name = s.Any.XMLName.Local
+
+	c = &Cascade{}
+	sizes := strings.Split(s.Any.Size, " ")
+	w, err := strconv.Atoi(sizes[0])
+	if err != nil {
+		return nil, "", err
+	}
+	h, err := strconv.Atoi(sizes[1])
+	if err != nil {
+		return nil, "", err
+	}
+	c.Size = image.Pt(w, h)
+	c.Stage = []CascadeStage{}
+
+	for _, stage := range s.Any.Stages {
+		cs := CascadeStage{
+			Classifier: []Classifier{},
+			Threshold:  stage.Stage_threshold,
+		}
+		for _, tree := range stage.Trees {
+			if tree.Tilted != 0 {
+				err = errors.New("Cascade does not support tilted features")
+				return
+			}
+
+			cls := Classifier{
+				Feature:   []Feature{},
+				Threshold: tree.Threshold,
+				Left:      tree.Left,
+				Right:     tree.Right,
+			}
+
+			for _, rect := range tree.Rects {
+				f, err := buildFeature(rect)
+				if err != nil {
+					return nil, "", err
+				}
+				cls.Feature = append(cls.Feature, f)
+			}
+
+			cs.Classifier = append(cs.Classifier, cls)
+		}
+		c.Stage = append(c.Stage, cs)
+	}
+
+	return
+}
+
+// ParseOpenCV produces a detection Cascade from an OpenCV XML file.
+func ParseOpenCV(r io.Reader) (cascade *Cascade, name string, err error) {
+	// BUG(crawshaw): tag-based parsing doesn't seem to work with <_>
+	buf, err := ioutil.ReadAll(r)
+	if err != nil {
+		return
+	}
+	buf = bytes.Replace(buf, []byte("<_>"), []byte("<grp>"), -1)
+	buf = bytes.Replace(buf, []byte("</_>"), []byte("</grp>"), -1)
+
+	s := &opencv_storage{}
+	err = xml.Unmarshal(buf, s)
+	if err != nil {
+		return
+	}
+	return buildCascade(s)
+}
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/opencv_parser_test.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/opencv_parser_test.go
new file mode 100644
index 000000000..343390499
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/opencv_parser_test.go
@@ -0,0 +1,75 @@
+// Copyright 2011 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package detect
+
+import (
+	"image"
+	"os"
+	"reflect"
+	"testing"
+)
+
+var (
+	classifier0 = Classifier{
+		Feature: []Feature{
+			Feature{Rect: image.Rect(0, 0, 3, 4), Weight: -1},
+			Feature{Rect: image.Rect(3, 4, 5, 6), Weight: 3.1},
+		},
+		Threshold: 0.03,
+		Left:      0.01,
+		Right:     0.8,
+	}
+	classifier1 = Classifier{
+		Feature: []Feature{
+			Feature{Rect: image.Rect(3, 7, 17, 11), Weight: -3.2},
+			Feature{Rect: image.Rect(3, 9, 17, 11), Weight: 2.},
+		},
+		Threshold: 0.11,
+		Left:      0.03,
+		Right:     0.83,
+	}
+	classifier2 = Classifier{
+		Feature: []Feature{
+			Feature{Rect: image.Rect(1, 1, 3, 3), Weight: -1.},
+			Feature{Rect: image.Rect(3, 3, 5, 5), Weight: 2.5},
+		},
+		Threshold: 0.07,
+		Left:      0.2,
+		Right:     0.4,
+	}
+	cascade = Cascade{
+		Stage: []CascadeStage{
+			CascadeStage{
+				Classifier: []Classifier{classifier0, classifier1},
+				Threshold:  0.82,
+			},
+			CascadeStage{
+				Classifier: []Classifier{classifier2},
+				Threshold:  0.22,
+			},
+		},
+		Size: image.Pt(20, 20),
+	}
+)
+
+func TestParseOpenCV(t *testing.T) {
+	file, err := os.Open("../../testdata/opencv.xml")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer file.Close()
+
+	cascadeFile, name, err := ParseOpenCV(file)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if name != "name_of_cascade" {
+		t.Fatalf("name: got %s want name_of_cascade", name)
+	}
+
+	if !reflect.DeepEqual(cascade, *cascadeFile) {
+		t.Errorf("got\n %v want\n %v", *cascadeFile, cascade)
+	}
+}
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/projector.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/projector.go
new file mode 100644
index 000000000..1ebd6db59
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/projector.go
@@ -0,0 +1,55 @@
+// Copyright 2011 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package detect
+
+import (
+	"image"
+)
+
+// projector allows projecting from a source Rectangle onto a target Rectangle.
+type projector struct {
+	// rx, ry is the scaling factor.
+	rx, ry float64
+	// dx, dy is the translation factor.
+	dx, dy float64
+	// r is the clipping region of the target.
+	r image.Rectangle
+}
+
+// newProjector creates a Projector with source src and target dst.
+func newProjector(dst image.Rectangle, src image.Rectangle) *projector {
+	return &projector{
+		rx: float64(dst.Dx()) / float64(src.Dx()),
+		ry: float64(dst.Dy()) / float64(src.Dy()),
+		dx: float64(dst.Min.X - src.Min.X),
+		dy: float64(dst.Min.Y - src.Min.Y),
+		r:  dst,
+	}
+}
+
+// pt projects p from the source rectangle onto the target rectangle.
+func (s *projector) pt(p image.Point) image.Point {
+	return image.Point{
+		clamp(s.rx*float64(p.X)+s.dx, s.r.Min.X, s.r.Max.X),
+		clamp(s.ry*float64(p.Y)+s.dy, s.r.Min.Y, s.r.Max.Y),
+	}
+}
+
+// rect projects r from the source rectangle onto the target rectangle.
+func (s *projector) rect(r image.Rectangle) image.Rectangle {
+	return image.Rectangle{s.pt(r.Min), s.pt(r.Max)}
+}
+
+// clamp rounds and clamps o to the integer range [x0, x1].
+func clamp(o float64, x0, x1 int) int {
+	x := int(o + 0.5)
+	if x < x0 {
+		return x0
+	}
+	if x > x1 {
+		return x1
+	}
+	return x
+}
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/projector_test.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/projector_test.go
new file mode 100644
index 000000000..c6d0b0cd5
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/detect/projector_test.go
@@ -0,0 +1,49 @@
+// Copyright 2011 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package detect
+
+import (
+	"image"
+	"reflect"
+	"testing"
+)
+
+type projectorTest struct {
+	dst  image.Rectangle
+	src  image.Rectangle
+	pdst image.Rectangle
+	psrc image.Rectangle
+}
+
+var projectorTests = []projectorTest{
+	{
+		image.Rect(0, 0, 6, 6),
+		image.Rect(0, 0, 2, 2),
+		image.Rect(0, 0, 6, 6),
+		image.Rect(0, 0, 2, 2),
+	},
+	{
+		image.Rect(0, 0, 6, 6),
+		image.Rect(0, 0, 2, 2),
+		image.Rect(3, 3, 6, 6),
+		image.Rect(1, 1, 2, 2),
+	},
+	{
+		image.Rect(30, 30, 40, 40),
+		image.Rect(10, 10, 20, 20),
+		image.Rect(32, 33, 34, 37),
+		image.Rect(12, 13, 14, 17),
+	},
+}
+
+func TestProjector(t *testing.T) {
+	for i, tt := range projectorTests {
+		pr := newProjector(tt.dst, tt.src)
+		res := pr.rect(tt.psrc)
+		if !reflect.DeepEqual(res, tt.pdst) {
+			t.Errorf("%d: got %v want %v", i, res, tt.pdst)
+		}
+	}
+}
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/graphicstest/Makefile b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/graphicstest/Makefile
new file mode 100644
index 000000000..7bfdf22d8
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/graphicstest/Makefile
@@ -0,0 +1,11 @@
+# Copyright 2011 The Graphics-Go Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+include $(GOROOT)/src/Make.inc
+
+TARG=code.google.com/p/graphics-go/graphics/graphicstest
+GOFILES=\
+	graphicstest.go\
+
+include $(GOROOT)/src/Make.pkg
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/graphicstest/graphicstest.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/graphicstest/graphicstest.go
new file mode 100644
index 000000000..ceb3a974d
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/graphicstest/graphicstest.go
@@ -0,0 +1,112 @@
+// Copyright 2011 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package graphicstest
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"image"
+	"image/color"
+	"os"
+)
+
+// LoadImage decodes an image from a file.
+func LoadImage(path string) (img image.Image, err error) {
+	file, err := os.Open(path)
+	if err != nil {
+		return
+	}
+	defer file.Close()
+	img, _, err = image.Decode(file)
+	return
+}
+
+func delta(u0, u1 uint32) int {
+	d := int(u0) - int(u1)
+	if d < 0 {
+		return -d
+	}
+	return d
+}
+
+func withinTolerance(c0, c1 color.Color, tol int) bool {
+	r0, g0, b0, a0 := c0.RGBA()
+	r1, g1, b1, a1 := c1.RGBA()
+	r := delta(r0, r1)
+	g := delta(g0, g1)
+	b := delta(b0, b1)
+	a := delta(a0, a1)
+	return r <= tol && g <= tol && b <= tol && a <= tol
+}
+
+// ImageWithinTolerance checks that each pixel varies by no more than tol.
+func ImageWithinTolerance(m0, m1 image.Image, tol int) error {
+	b0 := m0.Bounds()
+	b1 := m1.Bounds()
+	if !b0.Eq(b1) {
+		return errors.New(fmt.Sprintf("got bounds %v want %v", b0, b1))
+	}
+
+	for y := b0.Min.Y; y < b0.Max.Y; y++ {
+		for x := b0.Min.X; x < b0.Max.X; x++ {
+			c0 := m0.At(x, y)
+			c1 := m1.At(x, y)
+			if !withinTolerance(c0, c1, tol) {
+				e := fmt.Sprintf("got %v want %v at (%d, %d)", c0, c1, x, y)
+				return errors.New(e)
+			}
+		}
+	}
+	return nil
+}
+
+// SprintBox pretty prints the array as a hexidecimal matrix.
+func SprintBox(box []byte, width, height int) string {
+	buf := bytes.NewBuffer(nil)
+	i := 0
+	for y := 0; y < height; y++ {
+		for x := 0; x < width; x++ {
+			fmt.Fprintf(buf, " 0x%02x,", box[i])
+			i++
+		}
+		buf.WriteByte('\n')
+	}
+	return buf.String()
+}
+
+// SprintImageR pretty prints the red channel of src. It looks like SprintBox.
+func SprintImageR(src *image.RGBA) string {
+	w, h := src.Rect.Dx(), src.Rect.Dy()
+	i := 0
+	box := make([]byte, w*h)
+	for y := src.Rect.Min.Y; y < src.Rect.Max.Y; y++ {
+		for x := src.Rect.Min.X; x < src.Rect.Max.X; x++ {
+			off := (y-src.Rect.Min.Y)*src.Stride + (x-src.Rect.Min.X)*4
+			box[i] = src.Pix[off]
+			i++
+		}
+	}
+	return SprintBox(box, w, h)
+}
+
+// MakeRGBA returns an image with R, G, B taken from src.
+func MakeRGBA(src []uint8, width int) *image.RGBA {
+	b := image.Rect(0, 0, width, len(src)/width)
+	ret := image.NewRGBA(b)
+	i := 0
+	for y := b.Min.Y; y < b.Max.Y; y++ {
+		for x := b.Min.X; x < b.Max.X; x++ {
+			ret.SetRGBA(x, y, color.RGBA{
+				R: src[i],
+				G: src[i],
+				B: src[i],
+				A: 0xff,
+			})
+			i++
+		}
+	}
+	return ret
+}
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/interp/Makefile b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/interp/Makefile
new file mode 100644
index 000000000..4d8f524fb
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/interp/Makefile
@@ -0,0 +1,13 @@
+# Copyright 2012 The Graphics-Go Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+include $(GOROOT)/src/Make.inc
+
+TARG=code.google.com/p/graphics-go/graphics/interp
+GOFILES=\
+	bilinear.go\
+	doc.go\
+	interp.go\
+
+include $(GOROOT)/src/Make.pkg
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/interp/bilinear.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/interp/bilinear.go
new file mode 100644
index 000000000..e18321a15
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/interp/bilinear.go
@@ -0,0 +1,206 @@
+// Copyright 2012 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package interp
+
+import (
+	"image"
+	"image/color"
+	"math"
+)
+
+// Bilinear implements bilinear interpolation.
+var Bilinear Interp = bilinear{}
+
+type bilinear struct{}
+
+func (i bilinear) Interp(src image.Image, x, y float64) color.Color {
+	if src, ok := src.(*image.RGBA); ok {
+		return i.RGBA(src, x, y)
+	}
+	return bilinearGeneral(src, x, y)
+}
+
+func bilinearGeneral(src image.Image, x, y float64) color.Color {
+	p := findLinearSrc(src.Bounds(), x, y)
+	var fr, fg, fb, fa float64
+	var r, g, b, a uint32
+
+	r, g, b, a = src.At(p.low.X, p.low.Y).RGBA()
+	fr += float64(r) * p.frac00
+	fg += float64(g) * p.frac00
+	fb += float64(b) * p.frac00
+	fa += float64(a) * p.frac00
+
+	r, g, b, a = src.At(p.high.X, p.low.Y).RGBA()
+	fr += float64(r) * p.frac01
+	fg += float64(g) * p.frac01
+	fb += float64(b) * p.frac01
+	fa += float64(a) * p.frac01
+
+	r, g, b, a = src.At(p.low.X, p.high.Y).RGBA()
+	fr += float64(r) * p.frac10
+	fg += float64(g) * p.frac10
+	fb += float64(b) * p.frac10
+	fa += float64(a) * p.frac10
+
+	r, g, b, a = src.At(p.high.X, p.high.Y).RGBA()
+	fr += float64(r) * p.frac11
+	fg += float64(g) * p.frac11
+	fb += float64(b) * p.frac11
+	fa += float64(a) * p.frac11
+
+	var c color.RGBA64
+	c.R = uint16(fr + 0.5)
+	c.G = uint16(fg + 0.5)
+	c.B = uint16(fb + 0.5)
+	c.A = uint16(fa + 0.5)
+	return c
+}
+
+func (bilinear) RGBA(src *image.RGBA, x, y float64) color.RGBA {
+	p := findLinearSrc(src.Bounds(), x, y)
+
+	// Array offsets for the surrounding pixels.
+	off00 := offRGBA(src, p.low.X, p.low.Y)
+	off01 := offRGBA(src, p.high.X, p.low.Y)
+	off10 := offRGBA(src, p.low.X, p.high.Y)
+	off11 := offRGBA(src, p.high.X, p.high.Y)
+
+	var fr, fg, fb, fa float64
+
+	fr += float64(src.Pix[off00+0]) * p.frac00
+	fg += float64(src.Pix[off00+1]) * p.frac00
+	fb += float64(src.Pix[off00+2]) * p.frac00
+	fa += float64(src.Pix[off00+3]) * p.frac00
+
+	fr += float64(src.Pix[off01+0]) * p.frac01
+	fg += float64(src.Pix[off01+1]) * p.frac01
+	fb += float64(src.Pix[off01+2]) * p.frac01
+	fa += float64(src.Pix[off01+3]) * p.frac01
+
+	fr += float64(src.Pix[off10+0]) * p.frac10
+	fg += float64(src.Pix[off10+1]) * p.frac10
+	fb += float64(src.Pix[off10+2]) * p.frac10
+	fa += float64(src.Pix[off10+3]) * p.frac10
+
+	fr += float64(src.Pix[off11+0]) * p.frac11
+	fg += float64(src.Pix[off11+1]) * p.frac11
+	fb += float64(src.Pix[off11+2]) * p.frac11
+	fa += float64(src.Pix[off11+3]) * p.frac11
+
+	var c color.RGBA
+	c.R = uint8(fr + 0.5)
+	c.G = uint8(fg + 0.5)
+	c.B = uint8(fb + 0.5)
+	c.A = uint8(fa + 0.5)
+	return c
+}
+
+func (bilinear) Gray(src *image.Gray, x, y float64) color.Gray {
+	p := findLinearSrc(src.Bounds(), x, y)
+
+	// Array offsets for the surrounding pixels.
+	off00 := offGray(src, p.low.X, p.low.Y)
+	off01 := offGray(src, p.high.X, p.low.Y)
+	off10 := offGray(src, p.low.X, p.high.Y)
+	off11 := offGray(src, p.high.X, p.high.Y)
+
+	var fc float64
+	fc += float64(src.Pix[off00]) * p.frac00
+	fc += float64(src.Pix[off01]) * p.frac01
+	fc += float64(src.Pix[off10]) * p.frac10
+	fc += float64(src.Pix[off11]) * p.frac11
+
+	var c color.Gray
+	c.Y = uint8(fc + 0.5)
+	return c
+}
+
+type bilinearSrc struct {
+	// Top-left and bottom-right interpolation sources
+	low, high image.Point
+	// Fraction of each pixel to take. The 0 suffix indicates
+	// top/left, and the 1 suffix indicates bottom/right.
+	frac00, frac01, frac10, frac11 float64
+}
+
+func findLinearSrc(b image.Rectangle, sx, sy float64) bilinearSrc {
+	maxX := float64(b.Max.X)
+	maxY := float64(b.Max.Y)
+	minX := float64(b.Min.X)
+	minY := float64(b.Min.Y)
+	lowX := math.Floor(sx - 0.5)
+	lowY := math.Floor(sy - 0.5)
+	if lowX < minX {
+		lowX = minX
+	}
+	if lowY < minY {
+		lowY = minY
+	}
+
+	highX := math.Ceil(sx - 0.5)
+	highY := math.Ceil(sy - 0.5)
+	if highX >= maxX {
+		highX = maxX - 1
+	}
+	if highY >= maxY {
+		highY = maxY - 1
+	}
+
+	// In the variables below, the 0 suffix indicates top/left, and the
+	// 1 suffix indicates bottom/right.
+
+	// Center of each surrounding pixel.
+	x00 := lowX + 0.5
+	y00 := lowY + 0.5
+	x01 := highX + 0.5
+	y01 := lowY + 0.5
+	x10 := lowX + 0.5
+	y10 := highY + 0.5
+	x11 := highX + 0.5
+	y11 := highY + 0.5
+
+	p := bilinearSrc{
+		low:  image.Pt(int(lowX), int(lowY)),
+		high: image.Pt(int(highX), int(highY)),
+	}
+
+	// Literally, edge cases. If we are close enough to the edge of
+	// the image, curtail the interpolation sources.
+	if lowX == highX && lowY == highY {
+		p.frac00 = 1.0
+	} else if sy-minY <= 0.5 && sx-minX <= 0.5 {
+		p.frac00 = 1.0
+	} else if maxY-sy <= 0.5 && maxX-sx <= 0.5 {
+		p.frac11 = 1.0
+	} else if sy-minY <= 0.5 || lowY == highY {
+		p.frac00 = x01 - sx
+		p.frac01 = sx - x00
+	} else if sx-minX <= 0.5 || lowX == highX {
+		p.frac00 = y10 - sy
+		p.frac10 = sy - y00
+	} else if maxY-sy <= 0.5 {
+		p.frac10 = x11 - sx
+		p.frac11 = sx - x10
+	} else if maxX-sx <= 0.5 {
+		p.frac01 = y11 - sy
+		p.frac11 = sy - y01
+	} else {
+		p.frac00 = (x01 - sx) * (y10 - sy)
+		p.frac01 = (sx - x00) * (y11 - sy)
+		p.frac10 = (x11 - sx) * (sy - y00)
+		p.frac11 = (sx - x10) * (sy - y01)
+	}
+
+	return p
+}
+
+// TODO(crawshaw): When we have inlining, consider func (p *RGBA) Off(x, y) int
+func offRGBA(src *image.RGBA, x, y int) int {
+	return (y-src.Rect.Min.Y)*src.Stride + (x-src.Rect.Min.X)*4
+}
+func offGray(src *image.Gray, x, y int) int {
+	return (y-src.Rect.Min.Y)*src.Stride + (x - src.Rect.Min.X)
+}
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/interp/bilinear_test.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/interp/bilinear_test.go
new file mode 100644
index 000000000..242d70546
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/interp/bilinear_test.go
@@ -0,0 +1,143 @@
+// Copyright 2012 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package interp
+
+import (
+	"image"
+	"image/color"
+	"testing"
+)
+
+type interpTest struct {
+	desc     string
+	src      []uint8
+	srcWidth int
+	x, y     float64
+	expect   uint8
+}
+
+func (p *interpTest) newSrc() *image.RGBA {
+	b := image.Rect(0, 0, p.srcWidth, len(p.src)/p.srcWidth)
+	src := image.NewRGBA(b)
+	i := 0
+	for y := b.Min.Y; y < b.Max.Y; y++ {
+		for x := b.Min.X; x < b.Max.X; x++ {
+			src.SetRGBA(x, y, color.RGBA{
+				R: p.src[i],
+				G: p.src[i],
+				B: p.src[i],
+				A: 0xff,
+			})
+			i++
+		}
+	}
+	return src
+}
+
+var interpTests = []interpTest{
+	{
+		desc:     "center of a single white pixel should match that pixel",
+		src:      []uint8{0x00},
+		srcWidth: 1,
+		x:        0.5,
+		y:        0.5,
+		expect:   0x00,
+	},
+	{
+		desc: "middle of a square is equally weighted",
+		src: []uint8{
+			0x00, 0xff,
+			0xff, 0x00,
+		},
+		srcWidth: 2,
+		x:        1.0,
+		y:        1.0,
+		expect:   0x80,
+	},
+	{
+		desc: "center of a pixel is just that pixel",
+		src: []uint8{
+			0x00, 0xff,
+			0xff, 0x00,
+		},
+		srcWidth: 2,
+		x:        1.5,
+		y:        0.5,
+		expect:   0xff,
+	},
+	{
+		desc: "asymmetry abounds",
+		src: []uint8{
+			0xaa, 0x11, 0x55,
+			0xff, 0x95, 0xdd,
+		},
+		srcWidth: 3,
+		x:        2.0,
+		y:        1.0,
+		expect:   0x76, // (0x11 + 0x55 + 0x95 + 0xdd) / 4
+	},
+}
+
+func TestBilinearRGBA(t *testing.T) {
+	for _, p := range interpTests {
+		src := p.newSrc()
+
+		// Fast path.
+		c := Bilinear.(RGBA).RGBA(src, p.x, p.y)
+		if c.R != c.G || c.R != c.B || c.A != 0xff {
+			t.Errorf("expect channels to match, got %v", c)
+			continue
+		}
+		if c.R != p.expect {
+			t.Errorf("%s: got 0x%02x want 0x%02x", p.desc, c.R, p.expect)
+			continue
+		}
+
+		// Standard Interp should use the fast path.
+		cStd := Bilinear.Interp(src, p.x, p.y)
+		if cStd != c {
+			t.Errorf("%s: standard mismatch got %v want %v", p.desc, cStd, c)
+			continue
+		}
+
+		// General case should match the fast path.
+		cGen := color.RGBAModel.Convert(bilinearGeneral(src, p.x, p.y))
+		r0, g0, b0, a0 := c.RGBA()
+		r1, g1, b1, a1 := cGen.RGBA()
+		if r0 != r1 || g0 != g1 || b0 != b1 || a0 != a1 {
+			t.Errorf("%s: general case mismatch got %v want %v", p.desc, c, cGen)
+			continue
+		}
+	}
+}
+
+func TestBilinearSubImage(t *testing.T) {
+	b0 := image.Rect(0, 0, 4, 4)
+	src0 := image.NewRGBA(b0)
+	b1 := image.Rect(1, 1, 3, 3)
+	src1 := src0.SubImage(b1).(*image.RGBA)
+	src1.Set(1, 1, color.RGBA{0x11, 0, 0, 0xff})
+	src1.Set(2, 1, color.RGBA{0x22, 0, 0, 0xff})
+	src1.Set(1, 2, color.RGBA{0x33, 0, 0, 0xff})
+	src1.Set(2, 2, color.RGBA{0x44, 0, 0, 0xff})
+
+	tests := []struct {
+		x, y float64
+		want uint8
+	}{
+		{1, 1, 0x11},
+		{3, 1, 0x22},
+		{1, 3, 0x33},
+		{3, 3, 0x44},
+		{2, 2, 0x2b},
+	}
+
+	for _, p := range tests {
+		c := Bilinear.(RGBA).RGBA(src1, p.x, p.y)
+		if c.R != p.want {
+			t.Errorf("(%.0f, %.0f): got 0x%02x want 0x%02x", p.x, p.y, c.R, p.want)
+		}
+	}
+}
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/interp/doc.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/interp/doc.go
new file mode 100644
index 000000000..b115534cc
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/interp/doc.go
@@ -0,0 +1,25 @@
+// Copyright 2012 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+Package interp implements image interpolation.
+
+An interpolator provides the Interp interface, which can be used
+to interpolate a pixel:
+
+  c := interp.Bilinear.Interp(src, 1.2, 1.8)
+
+To interpolate a large number of RGBA or Gray pixels, an implementation 
+may provide a fast-path by implementing the RGBA or Gray interfaces.
+
+	i1, ok := i.(interp.RGBA)
+	if ok {
+		c := i1.RGBA(src, 1.2, 1.8)
+		// use c.R, c.G, etc
+		return
+	}
+	c := i.Interp(src, 1.2, 1.8)
+	// use generic color.Color
+*/
+package interp
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/interp/interp.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/interp/interp.go
new file mode 100644
index 000000000..560637d4a
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/interp/interp.go
@@ -0,0 +1,29 @@
+// Copyright 2012 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package interp
+
+import (
+	"image"
+	"image/color"
+)
+
+// Interp interpolates an image's color at fractional co-ordinates.
+type Interp interface {
+	// Interp interpolates (x, y).
+	Interp(src image.Image, x, y float64) color.Color
+}
+
+// RGBA is a fast-path interpolation implementation for image.RGBA.
+// It is common for an Interp to also implement RGBA.
+type RGBA interface {
+	// RGBA interpolates (x, y).
+	RGBA(src *image.RGBA, x, y float64) color.RGBA
+}
+
+// Gray is a fast-path interpolation implementation for image.Gray.
+type Gray interface {
+	// Gray interpolates (x, y).
+	Gray(src *image.Gray, x, y float64) color.Gray
+}
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/rotate.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/rotate.go
new file mode 100644
index 000000000..62bde1a08
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/rotate.go
@@ -0,0 +1,35 @@
+// Copyright 2011 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package graphics
+
+import (
+	"code.google.com/p/graphics-go/graphics/interp"
+	"errors"
+	"image"
+	"image/draw"
+)
+
+// RotateOptions are the rotation parameters.
+// Angle is the angle, in radians, to rotate the image clockwise.
+type RotateOptions struct {
+	Angle float64
+}
+
+// Rotate produces a rotated version of src, drawn onto dst.
+func Rotate(dst draw.Image, src image.Image, opt *RotateOptions) error {
+	if dst == nil {
+		return errors.New("graphics: dst is nil")
+	}
+	if src == nil {
+		return errors.New("graphics: src is nil")
+	}
+
+	angle := 0.0
+	if opt != nil {
+		angle = opt.Angle
+	}
+
+	return I.Rotate(angle).TransformCenter(dst, src, interp.Bilinear)
+}
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/rotate_test.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/rotate_test.go
new file mode 100644
index 000000000..bfc532a0a
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/rotate_test.go
@@ -0,0 +1,169 @@
+// Copyright 2011 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package graphics
+
+import (
+	"code.google.com/p/graphics-go/graphics/graphicstest"
+	"image"
+	"math"
+	"testing"
+
+	_ "image/png"
+)
+
+var rotateOneColorTests = []transformOneColorTest{
+	{
+		"onepixel-onequarter", 1, 1, 1, 1,
+		&RotateOptions{math.Pi / 2},
+		[]uint8{0xff},
+		[]uint8{0xff},
+	},
+	{
+		"onepixel-partial", 1, 1, 1, 1,
+		&RotateOptions{math.Pi * 2.0 / 3.0},
+		[]uint8{0xff},
+		[]uint8{0xff},
+	},
+	{
+		"onepixel-complete", 1, 1, 1, 1,
+		&RotateOptions{2 * math.Pi},
+		[]uint8{0xff},
+		[]uint8{0xff},
+	},
+	{
+		"even-onequarter", 2, 2, 2, 2,
+		&RotateOptions{math.Pi / 2.0},
+		[]uint8{
+			0xff, 0x00,
+			0x00, 0xff,
+		},
+		[]uint8{
+			0x00, 0xff,
+			0xff, 0x00,
+		},
+	},
+	{
+		"even-complete", 2, 2, 2, 2,
+		&RotateOptions{2.0 * math.Pi},
+		[]uint8{
+			0xff, 0x00,
+			0x00, 0xff,
+		},
+		[]uint8{
+			0xff, 0x00,
+			0x00, 0xff,
+		},
+	},
+	{
+		"line-partial", 3, 3, 3, 3,
+		&RotateOptions{math.Pi * 1.0 / 3.0},
+		[]uint8{
+			0x00, 0x00, 0x00,
+			0xff, 0xff, 0xff,
+			0x00, 0x00, 0x00,
+		},
+		[]uint8{
+			0xa2, 0x80, 0x00,
+			0x22, 0xff, 0x22,
+			0x00, 0x80, 0xa2,
+		},
+	},
+	{
+		"line-offset-partial", 3, 3, 3, 3,
+		&RotateOptions{math.Pi * 3 / 2},
+		[]uint8{
+			0x00, 0x00, 0x00,
+			0x00, 0xff, 0xff,
+			0x00, 0x00, 0x00,
+		},
+		[]uint8{
+			0x00, 0xff, 0x00,
+			0x00, 0xff, 0x00,
+			0x00, 0x00, 0x00,
+		},
+	},
+	{
+		"dot-partial", 4, 4, 4, 4,
+		&RotateOptions{math.Pi},
+		[]uint8{
+			0x00, 0x00, 0x00, 0x00,
+			0x00, 0xff, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00,
+		},
+		[]uint8{
+			0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0xff, 0x00,
+			0x00, 0x00, 0x00, 0x00,
+		},
+	},
+}
+
+func TestRotateOneColor(t *testing.T) {
+	for _, oc := range rotateOneColorTests {
+		src := oc.newSrc()
+		dst := oc.newDst()
+
+		if err := Rotate(dst, src, oc.opt.(*RotateOptions)); err != nil {
+			t.Errorf("rotate %s: %v", oc.desc, err)
+			continue
+		}
+		if !checkTransformTest(t, &oc, dst) {
+			continue
+		}
+	}
+}
+
+func TestRotateEmpty(t *testing.T) {
+	empty := image.NewRGBA(image.Rect(0, 0, 0, 0))
+	if err := Rotate(empty, empty, nil); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestRotateGopherSide(t *testing.T) {
+	src, err := graphicstest.LoadImage("../testdata/gopher.png")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	srcb := src.Bounds()
+	dst := image.NewRGBA(image.Rect(0, 0, srcb.Dy(), srcb.Dx()))
+	if err := Rotate(dst, src, &RotateOptions{math.Pi / 2.0}); err != nil {
+		t.Fatal(err)
+	}
+
+	cmp, err := graphicstest.LoadImage("../testdata/gopher-rotate-side.png")
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = graphicstest.ImageWithinTolerance(dst, cmp, 0x101)
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestRotateGopherPartial(t *testing.T) {
+	src, err := graphicstest.LoadImage("../testdata/gopher.png")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	srcb := src.Bounds()
+	dst := image.NewRGBA(image.Rect(0, 0, srcb.Dx(), srcb.Dy()))
+	if err := Rotate(dst, src, &RotateOptions{math.Pi / 3.0}); err != nil {
+		t.Fatal(err)
+	}
+
+	cmp, err := graphicstest.LoadImage("../testdata/gopher-rotate-partial.png")
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = graphicstest.ImageWithinTolerance(dst, cmp, 0x101)
+	if err != nil {
+		t.Fatal(err)
+	}
+}
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/scale.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/scale.go
new file mode 100644
index 000000000..7a7fe9696
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/scale.go
@@ -0,0 +1,31 @@
+// Copyright 2011 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package graphics
+
+import (
+	"code.google.com/p/graphics-go/graphics/interp"
+	"errors"
+	"image"
+	"image/draw"
+)
+
+// Scale produces a scaled version of the image using bilinear interpolation.
+func Scale(dst draw.Image, src image.Image) error {
+	if dst == nil {
+		return errors.New("graphics: dst is nil")
+	}
+	if src == nil {
+		return errors.New("graphics: src is nil")
+	}
+
+	b := dst.Bounds()
+	srcb := src.Bounds()
+	if b.Empty() || srcb.Empty() {
+		return nil
+	}
+	sx := float64(b.Dx()) / float64(srcb.Dx())
+	sy := float64(b.Dy()) / float64(srcb.Dy())
+	return I.Scale(sx, sy).Transform(dst, src, interp.Bilinear)
+}
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/scale_test.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/scale_test.go
new file mode 100644
index 000000000..9c2468f11
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/scale_test.go
@@ -0,0 +1,153 @@
+// Copyright 2011 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package graphics
+
+import (
+	"code.google.com/p/graphics-go/graphics/graphicstest"
+	"image"
+	"testing"
+
+	_ "image/png"
+)
+
+var scaleOneColorTests = []transformOneColorTest{
+	{
+		"down-half",
+		1, 1,
+		2, 2,
+		nil,
+		[]uint8{
+			0x80, 0x00,
+			0x00, 0x80,
+		},
+		[]uint8{
+			0x40,
+		},
+	},
+	{
+		"up-double",
+		4, 4,
+		2, 2,
+		nil,
+		[]uint8{
+			0x80, 0x00,
+			0x00, 0x80,
+		},
+		[]uint8{
+			0x80, 0x60, 0x20, 0x00,
+			0x60, 0x50, 0x30, 0x20,
+			0x20, 0x30, 0x50, 0x60,
+			0x00, 0x20, 0x60, 0x80,
+		},
+	},
+	{
+		"up-doublewidth",
+		4, 2,
+		2, 2,
+		nil,
+		[]uint8{
+			0x80, 0x00,
+			0x00, 0x80,
+		},
+		[]uint8{
+			0x80, 0x60, 0x20, 0x00,
+			0x00, 0x20, 0x60, 0x80,
+		},
+	},
+	{
+		"up-doubleheight",
+		2, 4,
+		2, 2,
+		nil,
+		[]uint8{
+			0x80, 0x00,
+			0x00, 0x80,
+		},
+		[]uint8{
+			0x80, 0x00,
+			0x60, 0x20,
+			0x20, 0x60,
+			0x00, 0x80,
+		},
+	},
+	{
+		"up-partial",
+		3, 3,
+		2, 2,
+		nil,
+		[]uint8{
+			0x80, 0x00,
+			0x00, 0x80,
+		},
+		[]uint8{
+			0x80, 0x40, 0x00,
+			0x40, 0x40, 0x40,
+			0x00, 0x40, 0x80,
+		},
+	},
+}
+
+func TestScaleOneColor(t *testing.T) {
+	for _, oc := range scaleOneColorTests {
+		dst := oc.newDst()
+		src := oc.newSrc()
+		if err := Scale(dst, src); err != nil {
+			t.Errorf("scale %s: %v", oc.desc, err)
+			continue
+		}
+
+		if !checkTransformTest(t, &oc, dst) {
+			continue
+		}
+	}
+}
+
+func TestScaleEmpty(t *testing.T) {
+	empty := image.NewRGBA(image.Rect(0, 0, 0, 0))
+	if err := Scale(empty, empty); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestScaleGopher(t *testing.T) {
+	dst := image.NewRGBA(image.Rect(0, 0, 100, 150))
+
+	src, err := graphicstest.LoadImage("../testdata/gopher.png")
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	// Down-sample.
+	if err := Scale(dst, src); err != nil {
+		t.Fatal(err)
+	}
+	cmp, err := graphicstest.LoadImage("../testdata/gopher-100x150.png")
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	err = graphicstest.ImageWithinTolerance(dst, cmp, 0)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	// Up-sample.
+	dst = image.NewRGBA(image.Rect(0, 0, 500, 750))
+	if err := Scale(dst, src); err != nil {
+		t.Fatal(err)
+	}
+	cmp, err = graphicstest.LoadImage("../testdata/gopher-500x750.png")
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	err = graphicstest.ImageWithinTolerance(dst, cmp, 0)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+}
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/shared_test.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/shared_test.go
new file mode 100644
index 000000000..e1cd21fb3
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/shared_test.go
@@ -0,0 +1,69 @@
+// Copyright 2011 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package graphics
+
+import (
+	"bytes"
+	"code.google.com/p/graphics-go/graphics/graphicstest"
+	"image"
+	"image/color"
+	"testing"
+)
+
+type transformOneColorTest struct {
+	desc      string
+	dstWidth  int
+	dstHeight int
+	srcWidth  int
+	srcHeight int
+	opt       interface{}
+	src       []uint8
+	res       []uint8
+}
+
+func (oc *transformOneColorTest) newSrc() *image.RGBA {
+	b := image.Rect(0, 0, oc.srcWidth, oc.srcHeight)
+	src := image.NewRGBA(b)
+	i := 0
+	for y := b.Min.Y; y < b.Max.Y; y++ {
+		for x := b.Min.X; x < b.Max.X; x++ {
+			src.SetRGBA(x, y, color.RGBA{
+				R: oc.src[i],
+				G: oc.src[i],
+				B: oc.src[i],
+				A: oc.src[i],
+			})
+			i++
+		}
+	}
+	return src
+}
+
+func (oc *transformOneColorTest) newDst() *image.RGBA {
+	return image.NewRGBA(image.Rect(0, 0, oc.dstWidth, oc.dstHeight))
+}
+
+func checkTransformTest(t *testing.T, oc *transformOneColorTest, dst *image.RGBA) bool {
+	for ch := 0; ch < 4; ch++ {
+		i := 0
+		res := make([]byte, len(oc.res))
+		for y := 0; y < oc.dstHeight; y++ {
+			for x := 0; x < oc.dstWidth; x++ {
+				off := (y-dst.Rect.Min.Y)*dst.Stride + (x-dst.Rect.Min.X)*4
+				res[i] = dst.Pix[off+ch]
+				i++
+			}
+		}
+
+		if !bytes.Equal(res, oc.res) {
+			got := graphicstest.SprintBox(res, oc.dstWidth, oc.dstHeight)
+			want := graphicstest.SprintBox(oc.res, oc.dstWidth, oc.dstHeight)
+			t.Errorf("%s: ch=%d\n got\n%s\n want\n%s", oc.desc, ch, got, want)
+			return false
+		}
+	}
+
+	return true
+}
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/thumbnail.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/thumbnail.go
new file mode 100644
index 000000000..d3ad7e8f7
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/thumbnail.go
@@ -0,0 +1,41 @@
+// Copyright 2011 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package graphics
+
+import (
+	"image"
+	"image/draw"
+)
+
+// Thumbnail scales and crops src so it fits in dst.
+func Thumbnail(dst draw.Image, src image.Image) error {
+	// Scale down src in the dimension that is closer to dst.
+	sb := src.Bounds()
+	db := dst.Bounds()
+	rx := float64(sb.Dx()) / float64(db.Dx())
+	ry := float64(sb.Dy()) / float64(db.Dy())
+	var b image.Rectangle
+	if rx < ry {
+		b = image.Rect(0, 0, db.Dx(), int(float64(sb.Dy())/rx))
+	} else {
+		b = image.Rect(0, 0, int(float64(sb.Dx())/ry), db.Dy())
+	}
+
+	buf := image.NewRGBA(b)
+	if err := Scale(buf, src); err != nil {
+		return err
+	}
+
+	// Crop.
+	// TODO(crawshaw): improve on center-alignment.
+	var pt image.Point
+	if rx < ry {
+		pt.Y = (b.Dy() - db.Dy()) / 2
+	} else {
+		pt.X = (b.Dx() - db.Dx()) / 2
+	}
+	draw.Draw(dst, db, buf, pt, draw.Src)
+	return nil
+}
diff --git a/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/thumbnail_test.go b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/thumbnail_test.go
new file mode 100644
index 000000000..d12659f17
--- /dev/null
+++ b/Godeps/_workspace/src/code.google.com/p/graphics-go/graphics/thumbnail_test.go
@@ -0,0 +1,53 @@
+// Copyright 2011 The Graphics-Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package graphics
+
+import (
+	"code.google.com/p/graphics-go/graphics/graphicstest"
+	"image"
+	"testing"
+
+	_ "image/png"
+)
+
+func TestThumbnailGopher(t *testing.T) {
+	dst := image.NewRGBA(image.Rect(0, 0, 80, 80))
+
+	src, err := graphicstest.LoadImage("../testdata/gopher.png")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := Thumbnail(dst, src); err != nil {
+		t.Fatal(err)
+	}
+	cmp, err := graphicstest.LoadImage("../testdata/gopher-thumb-80x80.png")
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = graphicstest.ImageWithinTolerance(dst, cmp, 0)
+	if err != nil {
+		t.Error(err)
+	}
+}
+
+func TestThumbnailLongGopher(t *testing.T) {
+	dst := image.NewRGBA(image.Rect(0, 0, 50, 150))
+
+	src, err := graphicstest.LoadImage("../testdata/gopher.png")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := Thumbnail(dst, src); err != nil {
+		t.Fatal(err)
+	}
+	cmp, err := graphicstest.LoadImage("../testdata/gopher-thumb-50x150.png")
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = graphicstest.ImageWithinTolerance(dst, cmp, 0)
+	if err != nil {
+		t.Error(err)
+	}
+}
-- 
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