func (c *Cut) SplitTo(img image.Image, outfile string) error {
if img, ok := img.(subImager); ok {
sub := img.SubImage(c.AsRect())
file, err := os.Create(outfile)
if err != nil {
return err
}
defer file.Close()
return png.Encode(file, sub)
} else {
return fmt.Errorf("Cannot take a SubImage")
}
}
func Histogram(img image.Image, rect image.Rectangle) ([]int, string) {
var hist []int
var pix []uint8
var colormodel string
var bounds image.Rectangle
stride := 0
n := 0
switch img := img.(type) {
case *image.RGBA:
colormodel = "rgba"
img = img.SubImage(rect).(*image.RGBA)
pix = img.Pix
n = 4
stride = img.Stride
bounds = img.Bounds()
case *image.NRGBA:
colormodel = "rgba"
img = img.SubImage(rect).(*image.NRGBA)
pix = img.Pix
n = 4
stride = img.Stride
bounds = img.Bounds()
// case *image.RGBA64: -- 16-bit values
case *image.Gray:
colormodel = "gray"
img = img.SubImage(rect).(*image.Gray)
pix = img.Pix
n = 1
stride = img.Stride
bounds = img.Bounds()
// case *image.Gray16: -- 16-bit values
case *image.YCbCr:
colormodel = "ycbcr"
hist = HistogramYCbCr(img, rect, false)
if hist != nil {
return hist, colormodel
}
default:
colormodel = "other"
}
if n > 0 {
hist = make([]int, n*256)
for y, o := bounds.Min.Y, 0; y < bounds.Max.Y; y, o = y+1, o+stride {
for x := 0; x < n*bounds.Dx(); x += n {
for i := 0; i < n; i++ {
hist[int(pix[o+x+i])+i*256] += 1
}
}
}
} else {
colormodel = "rgb"
hist = make([]int, 3*256)
for y := rect.Min.Y; y < rect.Max.Y; y += 1 {
for x := rect.Min.X; x < rect.Max.X; x += 1 {
color := img.At(x, y)
r, g, b, _ := color.RGBA()
hist[r>>8] += 1
hist[(g>>8)+256] += 1
hist[(b>>8)+512] += 1
}
}
}
return hist, colormodel
}