1 files changed, 43 insertions, 0 deletions
diff --git a/vendor/github.com/disintegration/imaging/histogram.go b/vendor/github.com/disintegration/imaging/histogram.go
new file mode 100644
index 000000000..aef333822
--- /dev/null
+++ b/vendor/github.com/disintegration/imaging/histogram.go
@@ -0,0 +1,43 @@
+package imaging
+
+import (
+	"image"
+)
+
+// Histogram returns a normalized histogram of an image.
+//
+// Resulting histogram is represented as an array of 256 floats, where
+// histogram[i] is a probability of a pixel being of a particular luminance i.
+func Histogram(img image.Image) [256]float64 {
+	src := toNRGBA(img)
+	width := src.Bounds().Max.X
+	height := src.Bounds().Max.Y
+
+	var histogram [256]float64
+	var total float64
+
+	if width == 0 || height == 0 {
+		return histogram		
+	}
+
+	for y := 0; y < height; y++ {
+		for x := 0; x < width; x++ {
+			i := y*src.Stride + x*4
+
+			r := src.Pix[i+0]
+			g := src.Pix[i+1]
+			b := src.Pix[i+2]
+
+			var y float32 = 0.299*float32(r) + 0.587*float32(g) + 0.114*float32(b)
+
+			histogram[int(y+0.5)]++
+			total++
+		}
+	}
+
+	for i := 0; i < 256; i++ {
+		histogram[i] = histogram[i] / total
+	}
+
+	return histogram
+}