On Fri, Jul 10, 2009 at 2:27 PM, Paul Johnson wrote:

Hi, everybody:

I filed a bug about Gimp after some checking, it was declared INVALID and I was referred here to ask how to fix it. I'm running Gimp 2.6.6 on Ubuntu 9.04.

I get bad results when saving images after Gimp converts the colormap. Its described here:

http://bugzilla.gnome.org/show_bug.cgi?id=567551

The lcms author and Sven Neumann looked into it and concluded it is not a fault of the Gimp, but rather it is something wrong in the original image. Images have Adobe1998 colormap embedded, but apparently that is a mistake. I don't know how they can tell what the colormap is, and I don't understand why the original image looks fine in GQView but it does not look fine after editing in the Gimp. If I bring the original image into Gimp and refuse Gimp's invitation to convert the colormap, and save the image, it is displayed fine in GQView. But if Gimp resets the colormap in any way, the image looks bad.

That's because the original color profile incorrectly specifies the meaning of the colors; garbage in, garbage out.

I just don't get it.

On a practical level, what is a user supposed to do?

1. How am I supposed to know if the wrong colormap is embedded in an image?

2. How can I follow Sven's advice to "unset" the colormap? In Gimp menus, I find only tools to convert or set the colormap, but not to unset it.

First: you are not talking about colormaps (that is an entire different issue, related to indexed images such as GIF. You are talking about ICC color profiles.

1. Image Properties (ALT-Enter) has a tab devoted to describing the ICC profile.

2. I would guess you should try to assign the default sRGB profile to this image -- as all 'dumb' (ICC-unaware) programs will display images as if they are sRGB, because most monitors approximate sRGB.

David