CMYK picture

Hello,

As I needed to use JMagick to read a CMYK picture, I had to implement to color separation case.

Please, have a look to the implementation I did. I am actually not an image expert, and I haven't been able to generate different kind of pictures to test different cases. But I have just managed to make it works with the image I had: a simple CMYK picture (no alpha, ...).

The code will probably need to be improved to handle any kind of ColorSeparation picture. Though, it may be a nice base for further developments.

Regards,

Philippe