Legacy ImageMagick Discussions Archive

Hi all,

I´ve been trying to convert to CMYK a simple JPEG image, but i´ve several questions, if any one can answer them.

What is the difference between using -colorspace CMYK and using -profile <CMYK_profile>.icc, i´m asking this because when i´m using -colorspace the image became CMYK and the colors change, but when i´m using -profile the image seams the same, and when i do indentify -verbose of the image the image remain sRGB. This is correct? Can anyone explain?

Another question is about the color, when i use the -colorspace option the black color gets very bad. I´ve seen an option to use -black-point-compensation but i think this only work with the -profile option, i´m i correct?

That said, i´m trying to convert an JPEG image to CMYK, witch i´ve done but the printer guys return to be that the black color is wrong? Any ideas?


Cheers,

Bigster

Most printers (human or mechanical) can handle RGB->CMYK conversion. If they can't, get a new printer.

If you really must convert RGB->CMYK:

- You probably need a profile. This will be specific to the printer, ink and paper. If you use a generic profile, it will be wrong.

You probably need to convert to the profile, not merely apply it. If the image doesn't already have a profile, you need two "-profile" operators. The first will apply an sRGB profile; the second will convert to the printer's CMYK profile.

"-black-point-compensation" is relevant only for "-profile", and must be applied first.