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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.

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6 Answers 6

up vote 9 down vote accepted

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 
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The sips invocation worked for me. –  Eric Rath Mar 16 '11 at 17:46

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.

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I get those options as well when I open an image that's already RGB. –  Patrick McElhaney Mar 8 '10 at 13:40

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

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Thanks. That led me to the answer, and a couple of GUI interfaces as well. –  Patrick McElhaney Mar 8 '10 at 14:37

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

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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!

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4  
In what program? –  Daniel Beck Aug 29 '12 at 17:00
    
"Preview". en.wikipedia.org/wiki/Preview_(Mac_OS) –  Fabian Zeindl Aug 4 at 10:25

For whatever reason I wasn't able to change the color mode with Preview and the Tools section. My needs my have been simpler, but I ended up just opening the image in Preview on my large external monitor and then using Skitch to take a screenshot of it. It fit my needs, it may fit yours.

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