Professional Color Conversion

[ame]

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

[snibgo]

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?

[ame]

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

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

Ame

[ame]

IM is installed starting here:

http://cactuslab.com/imagemagick/

Version is ImageMagick 6.7.3-2 for Mac OS X Lion

Ame

[snibgo]

Which file in dropbox? "originale.tif" is CMYK, and the conversion with ...

Code: Select all

convert originale.tif -profile sRGB.icc o.tiff

... looks fine to me. This is with IM v6.7.9, a slightly newer version than yours (but still rather old) .