My personal color space nightmare...

This image causes me difficulties, prints look different from the output on the screen.
I think it might be due to the fact that there are negative rgb values for the green channel everywhere, but I have no idea how to handle that in darktable…
I am curious what others can make of it!

PB130017.ORF (13.8 MB) (8.8 KB)

This file is licensed Creative Commons, By-Attribution, Share-Alike.

Using DNG-Converter tags there are no negative ProPhoto RGB values. After application of the Adobe Standard HSmap LUT and conversion to Adobe RGB these are the out of gamut areas (shows color channels that are either clipped or below zero).

Less than I thought. And this is the neutrally rendered image (-h) in Adobe RGB

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Here’s an attempt with the gamma compression on color calibration at 4

This is with gamma compression at 8

I admit I haven’t yet studied the color calibration module. Now, as a fun exercise I did print out both these jpgs. While they look wildly different on screen, here is the print output -

It’s a standard quality print on plain paper, using a basic epson inkjet. There’s hardly any difference between both!


ART trying to stay inside Adobe RGB gamut

With such a photo, I should have no hope that my local print shop would be able to accurately reproduce the displayed colors. They ask for sRGB profile if ever. I use that for standard print.
Two years ago, I used a professional lab for a few prints. They asked for tiff file with adobe RGB profile. They sent me their print profiles for soft proofing. Prints were so much better!

As display gamuts and printer gamuts are quite different, the result of print can be quite surprising.

Some people here locally print their photos. They can help you to set up a print workflow.

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PB130017.ORF.xmp (10.8 KB)

this time with the trick of desaturate the image with level tool before the conversion to the working space, and darkening after

PB130017.ORF.xmp (9.4 KB)

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Is your monitor calibrated? IrfanView does not have colour management. You should open the .jpg on Darktable and if your monitor is calibrated, compare.

One with @Soupy 's infrared technique! -

PB130017-showroom-blue-pink-purple-V2-S-sRGB.xmp (35.4 KB)


Do you mean Irfanview cannot use embedded profile ( always using sRGB), or cannot use a display profile, or both?

This is really a gamut nightmare :wink: . A decent monitor reproduces the sRGB color space which is also web standard. Colors directly derived from light sources are often difficult to map into this space.
It gets even worse when you try to print on paper. While the monitor uses additive color mixing, prints employ substractive color mixing having a differnt smaller color space using mostly CMYK as colors. The result then strongly depends on the software setup to map the colors and the possibilities of printer and paper used.

Here my simple attempt in color:

PB130017.ORF.xmp (6.7 KB)

But this image really screams for b&w:

PB130017.ORF.xmp (7.6 KB)


I don’t have SSF data for the Olympus E-M1, so my rendition relies on the libraw matrix. In rawproc, with a default-parameter filmic curve and only one color transform, camera -> sRGB at output:


That’s what I thought originally but the expanses of blues and violets produced by Adobe Standard processing fit pretty well within Adobe RGB as shown earlier, not an extreme case after all. sRGB has more trouble, for instance near the purple spotlight reflections.

Differences are mainly due to subjective application of saturation and contrast.


Yes, but you can reproduce this only on monitors with full AdobeRGB color space. If you don’t have such a device or want to publish/share on the web, it gets difficult. And printing is the real challenge :slight_smile: .

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Indeed. Still not as bad as originally suspected, Adobe Standard neutral rendition in sRGB (clipped/blocked color channels in sRGB)

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PB130017.ORF.xmp (11.1 KB)


That’s an interesting result.
When I inspected my pic in darktable I had negative values all over.
But digging more into it (Darktable 3.4):
The RGB values the color picker shows depend on the setting of histogram and softproof profile. If both profiles point to srgb I get negative values…
If I change the histogram profile to lets say linear ProPhoto the lowest RGB value I can find is zero…
Does that makes sense?

That’s exactly what happend to me. Two different jpg’s, same print results…
Thanks for your effort !

I got the icc profile of my printer service. But till now that was of little help…

The level tool trick is a nice one, thanks!

Well, black and white is not an option. The special thing about the building is, among other things, the lighting after sunset.
The colors change with the time. I made a series of pictures with certain details at different colors. One in black and white does not really fit into the series…
Your color result is a nice one!

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Unfortunately my monitor does not show full AdobeRGB color space…
So if I want to edit and print the image properly I need a better monitor and a print provider that can handle AdobeRGB, right?