Can I convert an image from CMYK to RGB in Mac OS X?

Question

Is there a way to convert a JPEG from CMYK to RGB, using Preview or any other tool built into Mac OS X?

I see I can go to Tools | Assign Profile… and select from a long list of options, including Generic CMYK Profile, but there's no RGB option.

Answer 1

I found three ways to do it.

1. Open the image with ColorSync.
2. Use the Apply ColorSync Profile to Images action in Automator.
3. Use sips (thanks, NSD) and supply the --matchTo argument. I wrote a shell script to convert an image using the Generic RGB Profile.

 

 #!/bin/bash          
 if [ -z "$1" ]; then        
     echo Converts an image to RGB color space
     echo 
     echo usage:  
     echo $0 filename 
     echo $0 source-file destination-file
     exit 
 fi           

 SOURCE_FILE=$1
 DESTINATION_FILE=$2    

 if [ -z "$2" ]; then 
     DESTINATION_FILE=$1
 fi

 sips --matchTo /System/Library/ColorSync/Profiles/Generic\ RGB\ Profile.icc $SOURCE_FILE --out $DESTINATION_FILE 

Answer 2

On my machine (10.6.2), two RGB profiles are offered: "Adobe RGC (1998)" and "Generic RGB Profile". Gimp (free) can do the conversion, too.

Answer 3

http://developer.apple.com/Mac/library/documentation/Darwin/Reference/ManPages/man1/sips.1.html

Answer 4

I didn't have the RGB colorsync profiles, so I imported the files into iPhoto and then exported them again. The exported photos were in RGB. Voila

Answer 5

It's really easy. You don't need to do any of these steps. In Preview, just go under Tools, Match to Profile, and under "Color Model" select RGB. The ColorSync Profile will change automatically. Save, and it's done!