Testbild colympICCtest.jpg (auf Englisch)

Alles was den ersten Teil von colymp (colymProfiler) betrifft: Erstellen einer Kalibrierung
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Marnix
Beiträge: 4
Registriert: Di 2. Jul 2024, 12:11

Testbild colympICCtest.jpg (auf Englisch)

Beitrag von Marnix »

So, I bought a colymp license key and created a profile for my camera and printer. So far so good.

Now, I’m working my way further through the manual and at chapter 5.1.1 “Andere Kamera-Farbräume als sRGB” there’s something I don’t understand.

I opened the testfile colympICCtest.jpg in several programs and found 2 that displayed a red cube instead of a green one: MS-Paint and OM Workspace. OM Workspace is the program that came with my Olympus OM-D camera.

So, I did what the manual says and in colymProfiler under Optionen → Ausgabe-Einstellungen, I selected Spezielles Profiel verwenden – colymRGBtoBRG.

In the print preview under Details Anzeigen I got the same results as in the manual:

MS-paint:
RGB-wert: R: 255 G: 50 B: 10 Lab-wert: L: 83 a: -127 b: 79 DeltaE: 0,14

OM Workspace:
RGB-wert: R: 255 G: 50 B: 10 Lab-wert: L: 83 a: -127 b: 79 DeltaE: 0,00

And the print was a green square. Funny, on the screen it’s red and on paper it’s green.

Now my question: I thought I could use this profile also to print other photos. But when I use it to print an arbitrary picture, both with MS-paint and OM Workspace the photos have a very green cast over them. And with the orignal profile I created, with sRGB selected instead of colymRGBtoBRG the photos are good.

I don’t understand what’s going on. What’s the use of colymRGBtoBRG if you can only print green squares with it?
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colympat
Beiträge: 16
Registriert: Fr 27. Jan 2012, 12:28

Re: Testbild colympICCtest.jpg (auf Englisch)

Beitrag von colympat »

The test image colympICCtest.jpg, and the profile embedded in it (colymRGBtoBRG) is used solely to analyze the behavior of the programs used for printing (e.g. MS-Paint, OM Workspace). As Windows itself does not offer direct support for color management (in contrast to ColorSync under macOS), various cases can occur here (with regard to color management of the print data). These cases are described in the manual in chapter 5.1.1 Camera Color Spaces Other Than sRGB (e.g. AdobeRGB) (cases 1-4).
The RGB and dE values you mentioned above show that both programs (MS Paint and OM Workspace) do not perform any color management when printing (4th case in chapter 5.1.1). The RGB values of the image are passed on unchanged to the printer (i.e. colymPrinterXPS).
In this case, colymPrinterXPS must be informed manually (in colymp>Options>Output Settings>Color space of the photographs) in which color space the images are available in OM Workspace (i.e. which working color space OM Workspace uses). Normally this will be sRGB (this is also the default setting of colymp). If you are working with AdobeRGB in OM Workspace, AdobeRGB should also be set in colymp at this point.

The profile colymRGBtoBRG would only have to be selected in colymp as "Color Space of the photographs" if you really wanted to print this special analysis image "colympICCtest.jpg"!
Marnix
Beiträge: 4
Registriert: Di 2. Jul 2024, 12:11

Re: Testbild colympICCtest.jpg (auf Englisch)

Beitrag von Marnix »

Ah, now it makes sense to me. It's just for testing purposes. The RGBtoBRG profile flips the color chanels so we can check that there's (no) color management.

Thanks for clearing that up.
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