Page 1 of 1

colors in CMYK -> sRGB conversion

Posted: 2010-12-30T09:03:11-07:00
by fxn
I am converting images from CMYK to sRGB. The command I use is

convert -colorspace sRGB -modulate 110 -quality 100 mona-lisa-cmyk.jpg mona-lisa-srgb.jpg

but the resulting image is too dark. See for example the original:

http://share.hashref.com/tmp/mona-lisa-cmyk.jpg

and the conversion:

http://share.hashref.com/tmp/mona-lisa-srgb.jpg

very different indeed.

I've tried several values for -modulate without luck, but I am not familiar with images and do not really know what else could I tune.

Could anyone help?

Re: colors in CMYK -> sRGB conversion

Posted: 2010-12-30T09:17:21-07:00
by markmarques
hi ...
if the original image is CMYK as far as I know you should define the colorspace CMYK before , apply whatever operation you need
and then define the RGB colorspace ...

something like:
convert -colorspace CMYK mona_lisa.cmyk.jpg -modulate 110 -colorspace RGB monalisa_rgb.jpg

PS: ( I do not have any image in cmyk so I can not try this) but give it a try ...

Re: colors in CMYK -> sRGB conversion

Posted: 2010-12-30T11:11:28-07:00
by fxn
Thanks, I tried your command but didn't make a difference.

In case you'd like to play around, this image uses CMYK

http://share.hashref.com/tmp/mona-lisa-cmyk.jpg

Re: colors in CMYK -> sRGB conversion

Posted: 2010-12-30T11:11:50-07:00
by fmw42
You should get better results using profiles. see http://www.imagemagick.org/Usage/formats/#profiles