How do I convert an image with colorspace YCbCr to CMYK?

Question

I've got images that have a YCbCr colorspace. But I want to make them CMYK. How do I do that? A Perl solution would be great. A command line (Ubuntu) solution would be good.

I've tried using ImageMagick but my images come out mostly black -- in fact it looks like the colors were reversed. Here is a sampling of commands I've tried:

convert -colorspace CMYK start.jpg end.jpg
convert -colorspace cmyk start.jpg end.jpg
convert -profile ISOcoated_v2_eci.icc -colorspace CMYK start.jpg end.jpg
convert -profile AdobeRGB1998.icc -profile ISOcoated_v2_eci.icc -colorspace CMYK start.jpg end.jpg

Answer 1

    convert YCbCr.jpg -colorspace cmyk cmyk.jpg 

Answer 2

Have you looked at the Motorola RGB to YCbCr Color Translation application note that describes how to convert 8-bit pixels from the RGB color space to the YCbCr with respect to the CCIR recommendation 601-2. The included source should give you a starting point for implementing your own conversion.

RGB to CMYK is straight forward.

As already suggested by user1074259 ImageMagick also supports converting to CMYK using the -colorspace cmyk option.