func imageConvert(src image.Image, dest draw.Image) draw.Image {
w, h := src.Bounds().Dx(), src.Bounds().Dy()
for y := 0; y < h; y += 1 {
for x := 0; x < w; x += 1 {
dest.Set(x, y, dest.ColorModel().Convert(src.At(x, y)))
}
}
return dest
}