On 03/03/2010 09:22 AM, Jason Simanek wrote:

Hello,

For web designers it is essential to have the option to either include or exclude color profiles on images that are created with Gimp. It would be great to have a checkbox on the save/export dialog or the Save for Web plugin dialog that would allow you to exclude the color profile.

Please excuse this ignorant question, but....

Could someone please explain or supply a link/reference that gives more background to the statement "For web designers it is essential to have the option to either include or exclude color profiles on images...".

I am sure I am missing something important. Why would you specifically want a color profile to NOT be present ... specifically for web-use images?

Thank you.

Jay

On Wed, 03 Mar 2010 08:22:42 -0600 Jason Simanek wrote:

I have the options 'Assign Color Profile' and 'Convert Color Profile'. Neither of these gives me the option to 'unset the color profile'. If the option isn't available next to these color profile options, what is the next logical place for that option to be located?

Try to use icc_colorspace plug-in bundled with Separate+.

(Demo video -> http://cue.yellowmagic.info/files/profile.mp4)

Separate+ is available at http://cue.yellowmagic.info/softwares/separate-plus/

On 03/03/2010 03:22 PM, Jason Simanek wrote:

Hello,

Apparently I was supposed to discuss any potential new features with the developer mailing list prior to filing a bug. Sven Neumann pointed this out to me. Thanks Sven.

There have been a UI proposal by yahvuu recently [1] where he suggests to have the option to export or not to export the color profile when exporting an image. We should continue that discussion. It is much easier to discuss an entire solution than a detail in a solution.

/ Martin

[1] http://lists.xcf.berkeley.edu/lists/gimp-developer/2010-February/024222.html

On 03/03/2010 10:08 AM, Jay Smith wrote:

On 03/03/2010 09:22 AM, Jason Simanek wrote:

Hello,

For web designers it is essential to have the option to either include or exclude color profiles on images that are created with Gimp. It would be great to have a checkbox on the save/export dialog or the Save for Web plugin dialog that would allow you to exclude the color profile.

Please excuse this ignorant question, but....

Could someone please explain or supply a link/reference that gives more background to the statement "For web designers it is essential to have the option to either include or exclude color profiles on images...".

I am sure I am missing something important. Why would you specifically want a color profile to NOT be present ... specifically for web-use images?

Thank you.

Jay

I have answered my own question, but it took about half hour of searching to find this.

Here is a great reference site exactly on this subject....

http://www.gballard.net/psd/go_live_page_profile/embeddedJPEGprofiles.html

For people like me, I recommend reading it thoroughly AND following all his links. It does go on a bit, but there are many pearls in it. Too bad he does not seem to talk about Gimp, but the content is still great.

Jay

On Wed, 2010-03-03 at 08:22 -0600, Jason Simanek wrote:

Sven suggested I just 'unset the color profile' on the image, but the option doesn't seem to exist. I'm running Gimp 2.6.7 on Ubuntu Karmic 9.10. Under

File > Image > Mode >

I have the options 'Assign Color Profile' and 'Convert Color Profile'.

You assign the sRGB profile. That is equivalent to un-setting the color profile.

Sven

Sven Neumann wrote:

You assign the sRGB profile. That is equivalent to un-setting the color profile.

If it actually does this, it's being highly un-intuitive. Assigning an sRGB profile would normally be expected to tag a file with sRGB, not at all the same thing as having no assigned profile.

Graeme Gill.

On Wed, 2010-03-03 at 13:19 -0600, Jason Simanek wrote:

Sven says:

You assign the sRGB profile.
That is equivalent to un-setting the color profile.

That's not true in my experience. Yes, sRGB should be as good as NOT having a profile since sRGB is the ASSUMED color space on most computersy. But Gimp still adds a color profile to the image: an sRGB color profile.

That would be a bug then. The intention of the lcms plug-in is that it deletes the "icc-profile" parasite if you assign the built-in sRGB profile. From a quick look at the code, I'd say that this is indeed what the plug-in is doing. What makes you think that the parasite would still be set?

Sven

On Thu, 2010-03-04 at 06:22 +1100, Graeme Gill wrote:

Sven Neumann wrote:

You assign the sRGB profile. That is equivalent to un-setting the color profile.

If it actually does this, it's being highly un-intuitive. Assigning an sRGB profile would normally be expected to tag a file with sRGB, not at all the same thing as having no assigned profile.

Untagged files are assumed to be sRGB. That is the assumption that the GIMP code makes all over the place. Actually most parts of GIMP (basically everything except the display code) don't care about the color profile at all and will assume sRGB no matter what profile is attached. It is thus recommended to convert all images to sRGB during the import into GIMP. This is surely far from ideal, but that's the current situation and it is not likely to change before everything is fully ported to GEGL.

Sven

Hi all,

Sven Neumann wrote:

Untagged files are assumed to be sRGB. That is the assumption that the GIMP code makes all over the place. Actually most parts of GIMP (basically everything except the display code) don't care about the color profile at all and will assume sRGB no matter what profile is attached. It is thus recommended to convert all images to sRGB during the import into GIMP.

This means that color management is simply incomplete or is something worse happening?

I'm asking because last year, about same time [1], you wrote:

Well, choosing a working profile other than sRGB is totally unsupported and will definitely lead to bad results.

I would call it useful partial support of color management if i can open an AdobeRGB file and apply, say, curves and gaussian blur and save the file with the color profile. In any case, the displayed image is correct and matches the saved image.

In contrast, the color selectors might be displaying wrong colors and pasting might auto-assign a wrong profile to new bitmaps. The layer modes and color tools like Hue-Saturation change their characteristics slightly according to the working space, but that's unavoidable with 8-bit processing anyway.

This is my understanding of the current state of color management. If something qualitatively different is happening, can you please give an example of how results might get deteriorated?

regards, yahvuu

[1] http://lists.xcf.berkeley.edu/lists/gimp-developer/2009-February/021598.html

On Wed, 2010-03-03 at 22:46 +0100, yahvuu wrote:

Sven Neumann wrote:

Untagged files are assumed to be sRGB. That is the assumption that the GIMP code makes all over the place. Actually most parts of GIMP (basically everything except the display code) don't care about the color profile at all and will assume sRGB no matter what profile is attached. It is thus recommended to convert all images to sRGB during the import into GIMP.

This means that color management is simply incomplete or is something worse happening?

It is incomplete.

I'm asking because last year, about same time [1], you wrote:

Well, choosing a working profile other than sRGB is totally unsupported and will definitely lead to bad results.

I would call it useful partial support of color management if i can open an AdobeRGB file and apply, say, curves and gaussian blur and save the file with the color profile. In any case, the displayed image is correct and matches the saved image.

If you don't mind that the Curves and Blur operations both make the assumption that they'd be working in sRGB, then that's fine. For a lot of operations it probably doesn't matter that much.

Sven

Hi,

On Wed, 2010-03-03 at 16:33 -0600, Jason Simanek wrote:

I understand that color management is complicated and probably not worth completely implementing until Gimp fully employs GEGL, but I think changing the menu so that

File > Image > Mode > Assign Color Profile > sRGB ACTUALLY applies the selected sRGB color profile to the image

and something like File > Image > Mode > Remove Color Profile would discard any color profile associated with the image

would be a simple change that would be a huge improvement to Gimp's user interface.

It's not that simple though. The assumption that no profile means sRGB is made in many more places. The Image Properties dialog for example will show you "sRGB built-in" for an image that has no profile attached.

The current behavior was proposed and accepted on this mailing-list before color management was added to GIMP. Of course it can be changed now, but such a change needs a complete proposal then that covers all places that are affected by it.

The point of the current behavior is that you need to make an assumption if no profile is attached to an image. Otherwise you could not even display this image. Without a color profile or an assumption about the meaning of the RGB values it's just numbers.

Sven

On 03/04/2010 02:13 PM, Jason Simanek wrote:

On 03/04/2010 02:14 AM, Sven Neumann wrote:

The point of the current behavior is that you need to make an assumption if no profile is attached to an image. Otherwise you could not even display this image. Without a color profile or an assumption about the meaning of the RGB values it's just numbers.

It's really unfortunate that the one color space that Gimp actually uses is sRGB, which has a fairly limited gamut (as I understand it). Of course, since it's the default color space of computer displays, sRGB makes perfect historical sense. But if it were instead something like Adobe RGB, Gimp would probably be pretty respectable as long as it color managed the transition from whatever original color space an image was in to the native wide-gamut RGB. And the export would work the same. In that situation the wide-gamut RGB would most likely be able to preserve all/most existing color variations in any image.

Sven, thanks for explaining the reality of color management in Gimp. Is somebody on the team already working on this or in this direction? Is there anything a non-programmer can do to contribute to this color management problem? Or is it just a matter of waiting for the developers to move all of Gimp over to GEGL's way of doing things?

I am currently working on improving color management in GIMP. If you would like to follow along, CC yourself on https://bugzilla.gnome.org/show_bug.cgi?id=608961 . I need to rev the spec, as I'm working off off a version of it that's a product of what I started with as well as discussions that happened after I originally wrote it.

As mentioned, I also discussed the spec here on the mailing list; see the thread "GIMP color-management spec and further discussion" which I started on 7 Feb 2010. I'm surprised that nobody referred to that spec or that prior discussion before now.

Finally, yahvuu created a nice spec for color management UI/UX. IMO, it's too ambitious for the first implementation, and I'd like to get something in that's basic but fully-functional, and covers usecases we don't support right now. So I will be implementing my spec, and once that basic functionality is in place, I'll look more closely at his spec.

Among the changes that I plan to make, which are pertinent to what's been discussed so far:
- The implicit assumption that untagged images use sRGB will be made explicit

Planned changes that aren't part of the spec: - I hope to make more (if not all) of the small previews color-managed - With any luck, I will get the sRGB profiles (2x3kB) included as part of the GIMP distribution, which will allow us to change how options are named — the user will trivially be able to embed an actual sRGB profile in addition to whatever they can do now.

If you have questions, let me know --xsdg

On 03/03/10 11:19, Jason Simanek wrote:

...elision by patrick
Gballard doesn't mention that Firefox, when its color management is enabled, actually does website color management correctly, since it applies color profiles to both images and HMTL/CSS-defined colors. But that really doesn't affect the discussion as it pertains to Gimp. And besides, Firefox's color management is not enabled by default.

Since 3.5 it's enabled by default.

That's not true in my experience. Yes, sRGB should be as good as NOT having a profile since sRGB is the ASSUMED color space on most computersy. But Gimp still adds a color profile to the image: an sRGB color profile. This still causes all of the color mismatch problems on websites thoroughly described on the gballard.net site mentioned above.

Now I'm confused I thought gballard said the opposite.

Patrick

On 04/03/10 21:22, Jason Simanek wrote:

... elision by patrick...
Thanks to browser type #2 I can only use color profiles on images that are not intended to be a part of the web site's design. If I do include color profiles on those images, every time I bring up the site in Safari it will look like my page elements don't match the flat colors defined in my site's HTML/CSS.

So the color mismatch I'm concerned about really only happens in Safari, but mismatches like that are not acceptable.

Did that resolve your confusion? Or just add to it?

No, now I get it completely. If it's a situation where you want managed and unmanaged to match, Safari is your enemy. Thanks!

Patrick