diff options
Diffstat (limited to 'Godeps/_workspace/src/github.com/nfnt/resize/ycc.go')
| -rw-r--r-- | Godeps/_workspace/src/github.com/nfnt/resize/ycc.go | 227 |
1 files changed, 227 insertions, 0 deletions
diff --git a/Godeps/_workspace/src/github.com/nfnt/resize/ycc.go b/Godeps/_workspace/src/github.com/nfnt/resize/ycc.go new file mode 100644 index 000000000..104159955 --- /dev/null +++ b/Godeps/_workspace/src/github.com/nfnt/resize/ycc.go @@ -0,0 +1,227 @@ +/* +Copyright (c) 2014, Charlie Vieth <charlie.vieth@gmail.com> + +Permission to use, copy, modify, and/or distribute this software for any purpose +with or without fee is hereby granted, provided that the above copyright notice +and this permission notice appear in all copies. + +THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH +REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND +FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, +INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS +OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER +TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF +THIS SOFTWARE. +*/ + +package resize + +import ( + "image" + "image/color" +) + +// ycc is an in memory YCbCr image. The Y, Cb and Cr samples are held in a +// single slice to increase resizing performance. +type ycc struct { + // Pix holds the image's pixels, in Y, Cb, Cr order. The pixel at + // (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*3]. + Pix []uint8 + // Stride is the Pix stride (in bytes) between vertically adjacent pixels. + Stride int + // Rect is the image's bounds. + Rect image.Rectangle + // SubsampleRatio is the subsample ratio of the original YCbCr image. + SubsampleRatio image.YCbCrSubsampleRatio +} + +// PixOffset returns the index of the first element of Pix that corresponds to +// the pixel at (x, y). +func (p *ycc) PixOffset(x, y int) int { + return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*3 +} + +func (p *ycc) Bounds() image.Rectangle { + return p.Rect +} + +func (p *ycc) ColorModel() color.Model { + return color.YCbCrModel +} + +func (p *ycc) At(x, y int) color.Color { + if !(image.Point{x, y}.In(p.Rect)) { + return color.YCbCr{} + } + i := p.PixOffset(x, y) + return color.YCbCr{ + p.Pix[i+0], + p.Pix[i+1], + p.Pix[i+2], + } +} + +func (p *ycc) Opaque() bool { + return true +} + +// SubImage returns an image representing the portion of the image p visible +// through r. The returned value shares pixels with the original image. +func (p *ycc) SubImage(r image.Rectangle) image.Image { + r = r.Intersect(p.Rect) + if r.Empty() { + return &ycc{SubsampleRatio: p.SubsampleRatio} + } + i := p.PixOffset(r.Min.X, r.Min.Y) + return &ycc{ + Pix: p.Pix[i:], + Stride: p.Stride, + Rect: r, + SubsampleRatio: p.SubsampleRatio, + } +} + +// newYCC returns a new ycc with the given bounds and subsample ratio. +func newYCC(r image.Rectangle, s image.YCbCrSubsampleRatio) *ycc { + w, h := r.Dx(), r.Dy() + buf := make([]uint8, 3*w*h) + return &ycc{Pix: buf, Stride: 3 * w, Rect: r, SubsampleRatio: s} +} + +// YCbCr converts ycc to a YCbCr image with the same subsample ratio +// as the YCbCr image that ycc was generated from. +func (p *ycc) YCbCr() *image.YCbCr { + ycbcr := image.NewYCbCr(p.Rect, p.SubsampleRatio) + var off int + + switch ycbcr.SubsampleRatio { + case image.YCbCrSubsampleRatio422: + for y := ycbcr.Rect.Min.Y; y < ycbcr.Rect.Max.Y; y++ { + yy := (y - ycbcr.Rect.Min.Y) * ycbcr.YStride + cy := (y - ycbcr.Rect.Min.Y) * ycbcr.CStride + for x := ycbcr.Rect.Min.X; x < ycbcr.Rect.Max.X; x++ { + xx := (x - ycbcr.Rect.Min.X) + yi := yy + xx + ci := cy + xx/2 + ycbcr.Y[yi] = p.Pix[off+0] + ycbcr.Cb[ci] = p.Pix[off+1] + ycbcr.Cr[ci] = p.Pix[off+2] + off += 3 + } + } + case image.YCbCrSubsampleRatio420: + for y := ycbcr.Rect.Min.Y; y < ycbcr.Rect.Max.Y; y++ { + yy := (y - ycbcr.Rect.Min.Y) * ycbcr.YStride + cy := (y/2 - ycbcr.Rect.Min.Y/2) * ycbcr.CStride + for x := ycbcr.Rect.Min.X; x < ycbcr.Rect.Max.X; x++ { + xx := (x - ycbcr.Rect.Min.X) + yi := yy + xx + ci := cy + xx/2 + ycbcr.Y[yi] = p.Pix[off+0] + ycbcr.Cb[ci] = p.Pix[off+1] + ycbcr.Cr[ci] = p.Pix[off+2] + off += 3 + } + } + case image.YCbCrSubsampleRatio440: + for y := ycbcr.Rect.Min.Y; y < ycbcr.Rect.Max.Y; y++ { + yy := (y - ycbcr.Rect.Min.Y) * ycbcr.YStride + cy := (y/2 - ycbcr.Rect.Min.Y/2) * ycbcr.CStride + for x := ycbcr.Rect.Min.X; x < ycbcr.Rect.Max.X; x++ { + xx := (x - ycbcr.Rect.Min.X) + yi := yy + xx + ci := cy + xx + ycbcr.Y[yi] = p.Pix[off+0] + ycbcr.Cb[ci] = p.Pix[off+1] + ycbcr.Cr[ci] = p.Pix[off+2] + off += 3 + } + } + default: + // Default to 4:4:4 subsampling. + for y := ycbcr.Rect.Min.Y; y < ycbcr.Rect.Max.Y; y++ { + yy := (y - ycbcr.Rect.Min.Y) * ycbcr.YStride + cy := (y - ycbcr.Rect.Min.Y) * ycbcr.CStride + for x := ycbcr.Rect.Min.X; x < ycbcr.Rect.Max.X; x++ { + xx := (x - ycbcr.Rect.Min.X) + yi := yy + xx + ci := cy + xx + ycbcr.Y[yi] = p.Pix[off+0] + ycbcr.Cb[ci] = p.Pix[off+1] + ycbcr.Cr[ci] = p.Pix[off+2] + off += 3 + } + } + } + return ycbcr +} + +// imageYCbCrToYCC converts a YCbCr image to a ycc image for resizing. +func imageYCbCrToYCC(in *image.YCbCr) *ycc { + w, h := in.Rect.Dx(), in.Rect.Dy() + r := image.Rect(0, 0, w, h) + buf := make([]uint8, 3*w*h) + p := ycc{Pix: buf, Stride: 3 * w, Rect: r, SubsampleRatio: in.SubsampleRatio} + var off int + + switch in.SubsampleRatio { + case image.YCbCrSubsampleRatio422: + for y := in.Rect.Min.Y; y < in.Rect.Max.Y; y++ { + yy := (y - in.Rect.Min.Y) * in.YStride + cy := (y - in.Rect.Min.Y) * in.CStride + for x := in.Rect.Min.X; x < in.Rect.Max.X; x++ { + xx := (x - in.Rect.Min.X) + yi := yy + xx + ci := cy + xx/2 + p.Pix[off+0] = in.Y[yi] + p.Pix[off+1] = in.Cb[ci] + p.Pix[off+2] = in.Cr[ci] + off += 3 + } + } + case image.YCbCrSubsampleRatio420: + for y := in.Rect.Min.Y; y < in.Rect.Max.Y; y++ { + yy := (y - in.Rect.Min.Y) * in.YStride + cy := (y/2 - in.Rect.Min.Y/2) * in.CStride + for x := in.Rect.Min.X; x < in.Rect.Max.X; x++ { + xx := (x - in.Rect.Min.X) + yi := yy + xx + ci := cy + xx/2 + p.Pix[off+0] = in.Y[yi] + p.Pix[off+1] = in.Cb[ci] + p.Pix[off+2] = in.Cr[ci] + off += 3 + } + } + case image.YCbCrSubsampleRatio440: + for y := in.Rect.Min.Y; y < in.Rect.Max.Y; y++ { + yy := (y - in.Rect.Min.Y) * in.YStride + cy := (y/2 - in.Rect.Min.Y/2) * in.CStride + for x := in.Rect.Min.X; x < in.Rect.Max.X; x++ { + xx := (x - in.Rect.Min.X) + yi := yy + xx + ci := cy + xx + p.Pix[off+0] = in.Y[yi] + p.Pix[off+1] = in.Cb[ci] + p.Pix[off+2] = in.Cr[ci] + off += 3 + } + } + default: + // Default to 4:4:4 subsampling. + for y := in.Rect.Min.Y; y < in.Rect.Max.Y; y++ { + yy := (y - in.Rect.Min.Y) * in.YStride + cy := (y - in.Rect.Min.Y) * in.CStride + for x := in.Rect.Min.X; x < in.Rect.Max.X; x++ { + xx := (x - in.Rect.Min.X) + yi := yy + xx + ci := cy + xx + p.Pix[off+0] = in.Y[yi] + p.Pix[off+1] = in.Cb[ci] + p.Pix[off+2] = in.Cr[ci] + off += 3 + } + } + } + return &p +} |