func newSetFuncCMYK(p *image.CMYK) SetFunc {
return func(x, y int, r, g, b, a uint32) {
rr := uint32(r >> 8)
gg := uint32(g >> 8)
bb := uint32(b >> 8)
w := rr
if w < gg {
w = gg
}
if w < bb {
w = bb
}
var c8, m8, y8, k8 uint8
if w == 0 {
k8 = 0xff
} else {
c8 = uint8((w - rr) * 0xff / w)
m8 = uint8((w - gg) * 0xff / w)
y8 = uint8((w - bb) * 0xff / w)
k8 = uint8(0xff - w)
}
i := p.PixOffset(x, y)
p.Pix[i+0] = c8
p.Pix[i+1] = m8
p.Pix[i+2] = y8
p.Pix[i+3] = k8
}
}
func newAtFuncCMYK(p *image.CMYK) AtFunc {
return func(x, y int) (r, g, b, a uint32) {
i := p.PixOffset(x, y)
w := uint32(0xffff - uint32(p.Pix[i+3])*0x101)
r = uint32(0xffff-uint32(p.Pix[i+0])*0x101) * w / 0xffff
g = uint32(0xffff-uint32(p.Pix[i+1])*0x101) * w / 0xffff
b = uint32(0xffff-uint32(p.Pix[i+2])*0x101) * w / 0xffff
a = 0xffff
return
}
}