Legacy ImageMagick Discussions Archive

Hi I need to convert CYMYK images, all with embedded profiles (like Fogra 39, Uncoated Fogra 29...) to sRGB.
Following the manual and example here:

In Changing Colorspace via Profiles section it say:

convert cmyk_image.jpg -profile sRGB.icc rgb_image.jpg

If there is an embedded profile then a single of "-profile" operator will immediately define the output profile.

This don't produce a correct match.
Seems that a double step is required like:

convert cmyk_image.jpg -profile "CMYK.icc" -profile "RGB.icc" output_image.jpg


But again in the manual seems to be bad idea:

WARNING:
If the original image already contains a profile, for example a CMYK profile, then given two profile conversions is a bad idea.
For example

convert cmyk_image.jpg -profile "CMYK.icc" -profile "RGB.icc" \
output_image.jpg
Will result in a CMYK -> CMYK -> RGB conversion. But as CMYK is not symmetric, the the extra conversion step can result in a disastrous color conversion. (See the IM Forum discussion Question on ICC profile conversion behaviour)

Of course the CMYK.icc profile MUST be the same embedded in the image otherwise you have a color shift.

All shoudl be executed considering the embdded profile, so with one conversion only.

I would like to know if there is a bug in the manual or for CMYK to RGB a double conversion is required.

Ame

The advice in the manual is correct, but doesn't cover all situations. Can you post an example image? (Put it in dropbox or somewhere, and post a link here.)

What version IM are you running?

This is the link to download a test images in CMYK with Uncoated Frogra 29 embedded.

https://www.dropbox.com/sh/fqnzexuthwmwrbm/OACu1GfHey

Ame

IM is installed starting here:

http://cactuslab.com/imagemagick/

Version is ImageMagick 6.7.3-2 for Mac OS X Lion

Ame

Which file in dropbox? "originale.tif" is CMYK, and the conversion with ... ... looks fine to me. This is with IM v6.7.9, a slightly newer version than yours (but still rather old) .