Color space weirdness?


While trying to find out where my color space disappeared in my workflow (spoiler: Gimp export) I also found something weird in Darktable. As I’m not sure it a bug or a lack of understanding on my side I thought to first ask here.

My camera (Sony A65) can produce raw files in AdobeRGB. When processing such a file I set the output color space in darktable explicit to AdobeRGB and leave the setting “Export profile” in the the export module to “Image setting” expecting the resulting TIF or JPG to have the exif info for this color space:

Color space: Uncalibrated
Interoperability: R03

But, after exporting the resulting file from Darktable, the color space is set to sRGB while the Interoperability is still R03.

Setting the “export profile” in the export module explicit to “Adobe RBG” I DO get the expected uncalibrated/R03

So as it seems the export profile “Image setting” does something different from what I expect and the output color space module in Darktable doesn’t really do anything at all?!

Anyone who can shine some light? Thanks!

No, the color space setting in the camera does not affect the raw data and applies only to the embedded JPEG preview and thumbnail.

Sure, I understand that the raw data isn’t in any color space as such although it should have enough information to be processed into AdobeRGB color space if that’s what I ask for in Darktable.

Remains the fact that I ask for an output profile in the aRGB and get an an sRGB unless I also explicitly mention it again the export module which makes me wonder what the output color space module is supposed to do and why this isn’t honored in the export.

A darktable dev will need to comment on your finding. The Exif 2.3 specification reads:

If a color space other than sRGB is used, Uncalibrated (=FFFF.H) is set.

The export profile in the output color profile module is used when exporting the image. Then, in the export module, you can overwrite it. If when exporting you use the setting image settings, that means you want to use the export profile on the output color profile module.

As long as you explicitly define the colour profiles you want to use, you should be fine. I do this to account for the off chance where the raw processor or editor defaults to something unintended.

As for the tag, @Morgan_Hardwood is correct. It happens almost all of the time, though you get manufacturers who don’t follow the rules. Personally, since I do raw processing and don’t care about the preview images, I simply keep the colour space at its default (sRGB). I don’t see any point in having AdobeRGB JPGs anyway.

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Well, That’s what I expected and in that case it’s a bug.

When using the “image settings” in the export module and “AdobeRGB” as output profile Darktable gives me sRGB instead of uncalibrated.

Only when I set AdobeRGB explicitly in the export module I get uncalibrated. Both cases do give the Interoperability as R03 though.


Thanks, and of course he’s right in that RAW doesn’t have the concept of a color space until it’s converted into an other format.
As for the use of AdobeRGB, it’s for prints. The behaviour as described also goes for Tiffs for example. It’s just unexpected behaviour resulting in a wrong color space setting in the output.

I just want a consistent color space from the beginning in darktable until the end in preparing for use in digikam. Gimp for now is the main problem, but that doesn’t stop me from checking other issues in the flow too…


I see. However, I still explicitly state the colour profiles, since I wouldn’t want to leave things to chance, especially for printing. Also, I would consider using a profile specific or calibrated to the printer. That is outside of my comfort zone but there are several threads that address this.

I don’t know of a printer yet made that will accommodate the AdobeRGB gamut. I think the camera manufacturers include that option for OOC JPEGs that folks might subsequently edit, in an attempt to keep from crushing colors too soon.

I’d encourage instead for you to think of the colorspace information as describing how the image information is encoded with respect to color. You want that attached profile to accurately describe the image’s colorspace, so that it can be transformed appropriately as you head from the original camera’s color response to eventual output for display or printing. It doesn’t have to be consistent, but it has to be correct at every stage.

Of course, and that was the root of the problem. I thought I did explicitly set it by setting the output profile to AdobeRGB and then finding sRGB in the resulting file. So I have to set it also in the export module, but that made me wonder about the what and why of the output profile module. Shouldn’t have to set it twice after all…

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There is a use for specifying the profile in export; it is not the same thing. Let me explain.

1 When you export, there is no guarantee that your files were edited in the same manner. I.e., it is possible for them to have different output profiles.

2 You might export multiple times for different clients or purposes. Hence, different profiles are necessary.

Could still be a bug or at least something worth clarifying in the interface or docs.

Works fine for me, what dt version and OS are you using?

Sme printers, like my Epson SureColor P600, explicitly support AdobeRGB. Its very convienent. You then select a paper profile in the print driver and the printer takes care of the rest.

Interesting… does the print actually render in AdobeRGB or does it convert to printer color space assuming input is AdobeRGB?

Hmm… Doubt that the printer alone can.
Depends on the paper gamut as well.
Lousy paper = lousy gamut.

Very true, but I use Epson papers as well, and they do all the paper calibration for me. :slight_smile:

I assume it maps it to an internal color space, but I am not sure. Even working there for 5 years, I never found out.