Fix wrong colors of resized image.YCbCr images.

Fixes issue #31.
The color value of every pixel of the resized image is created from the YCbCr
colors of the input image. Therefore each of the three components have the same
sample rate. This is the 4:4:4 chroma subsampling and the output images are
now created accordingly.

resize.go

@@ -167,7 +167,7 @@ func Resize(width, height uint, img image.Image, interp InterpolationFunction) i
 		// accessing the YCbCr arrays in a tight loop is slow.
 		// converting the image to ycc increases performance by 2x.
 		temp := newYCC(image.Rect(0, 0, input.Bounds().Dy(), int(width)), input.SubsampleRatio)
-		result := newYCC(image.Rect(0, 0, int(width), int(height)), input.SubsampleRatio)
+		result := newYCC(image.Rect(0, 0, int(width), int(height)), image.YCbCrSubsampleRatio444)
 
 		coeffs, offset, filterLength := createWeights8(temp.Bounds().Dy(), taps, blur, scaleX, kernel)
 		in := imageYCbCrToYCC(input)
@@ -409,7 +409,7 @@ func resizeNearest(width, height uint, scaleX, scaleY float64, img image.Image,
 		// accessing the YCbCr arrays in a tight loop is slow.
 		// converting the image to ycc increases performance by 2x.
 		temp := newYCC(image.Rect(0, 0, input.Bounds().Dy(), int(width)), input.SubsampleRatio)
-		result := newYCC(image.Rect(0, 0, int(width), int(height)), input.SubsampleRatio)
+		result := newYCC(image.Rect(0, 0, int(width), int(height)), image.YCbCrSubsampleRatio444)
 
 		coeffs, offset, filterLength := createWeightsNearest(temp.Bounds().Dy(), taps, blur, scaleX)
 		in := imageYCbCrToYCC(input)