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Which color profile transformations are done when using SnapshotUtilsEx ?

Participant ,
Jul 27, 2021 Jul 27, 2021

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Hi,

 

I have a frame filled with CMYK 0/20/100/0 (orange).

 

Using SnapshotUtilsEx I save it to JPEG RGB with current document profile: I get an image whose colors are quite OK. Of course if depends on CMYK current profile.

 

I then import this JPEG image with it's profile, then save it to a 2nd JPEG RGB with profile. 

 

If I compare the 2 JPEGs: the colors are different...

 

I suppose that the SnapshotUtilsEx::Draw with IShape::kPrinting does profiles conversions... but which ones?

 

I've tried similar things using TIF/ CIELab instead of JPEG => similar problem.

 

I'd just like to have the same color in the 2 exported files...

 

Any idea ?

 

TIA,

 

J.

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Adobe Community Professional ,
Jul 27, 2021 Jul 27, 2021

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When you select the placed screen capture, what profile is listed in the Link Info panel?

 

 then save it to a 2nd JPEG RGB with profile. 

 

By save I assume you mean an InDesign Export to JPEG (RGB), and in the Export dialog you are checking Embed Color Profile? What application are you using to compare the two JPEGs?

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Participant ,
Jul 28, 2021 Jul 28, 2021

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Hi,

 

1. I have the InDesign workspace RGB Profile, as expected.

 

2. I use SDK functions. I've compiled and made some tweaks in SnapShot SDK sample project 

 

 

 

for (int32 i = 0; i < itemList.Length(); i++)
			snapshot->Draw(
				itemList[i],
				IShape::kPrinting,
				true,
				7.0,
				kTrue,
				SnapshotUtils::kXPHigh
			);

and added true (allow saving color profile)

 

// Export the bitmap to the right format
		if (fFormatClass == kJPEGImageWriteFormatBoss)
		{
			int32 encoding = fSnapshotPrefsData->GetJPEGEncoding();
			int32 quality = fSnapshotPrefsData->GetJPEGQuality();
			status = snapshot->ExportImageToJPEG(stream, 
									(SnapshotUtils::SSJPEGEncoding)encoding, 
									(SnapshotUtils::SSJPEGQuality)quality,
									true); // JAKO: added true
		} 

3. For comparing JPEGs I use PhotoShop and eyedropper tool to see RVB values and... they are different...

 

J.

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Adobe Community Professional ,
Jul 28, 2021 Jul 28, 2021

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You will know, of course, that orange can't be reproduced in CMYK, it comes out as a kind of brown, just as you can't reproduce bright green in CMYK.

 

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Participant ,
Jul 28, 2021 Jul 28, 2021

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Yes, this is not really the problem 🙂

 

Thx !

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Adobe Community Professional ,
Jul 28, 2021 Jul 28, 2021

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Can you share the starting JPEG?

 

I wouldn’t expect an exact value match because the placed JPEG is going to be resampled and recompressed on the JPEG export

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Participant ,
Jul 29, 2021 Jul 29, 2021

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Hi,

 

I can't FTM because it's on my Mac which is at home and I'm working on my PC at the office.

 

I've try to reproduce the problem on my PC and... the InDesign behaviour (same version, CC2021) seems different re this point. But I'm not 100% sure because so many color settings seem involved, I'll need to double check everything...

 

I don't believe the compression is involved as I'm testing with only 1 color...

 

Having these settings:

RGB profile: sRGB IEC61966-2.1

CMYK profile: Coated FOGRA39 (ISO 12647-2:2004)

 

My guess (but does not seem to apply on PC) is

 

During the first snaphot => the CMYK color is converted into RGB (FOGRA39  => sRGB ) => Image1.jpg

The Image1.jpg is imported with its sRGB profile into InDesign

During the 2nd snapshot => the RGB is first converted into CMYK (sRGB => FOGRA) then converted back to RGB  (FOGRA39  => sRGB). 

 

If you do such thing with PhotoShop, with these 2 profiles:

 

Create a CMYK PS file.

Fill it with 0/20/100/0 color

Convert into sRBG (Adobe( ACE) / Perception / Use black point compensation) => RVB 205/204/0

Convert into FOGRA39 (same settings) => CMYK 5/22/91/0

Convert into sRGB => 243/197/31.

 

The setting Mode (here 'perception') seems to be involved.

 

If you use 'Absolute colorimeric' , after conversion to FOGRA => 0/20/93/0

then after conversion to RGB => 255/204/3...

 

Will try to make some similar tests on Mac this evening and let you know (if not this evening, after the 15th of August due to holidays).

 

Cheers,

 

J.

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Participant ,
Aug 18, 2021 Aug 18, 2021

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Hi, back after holidays 🙂

 

A little typo: after first CMYK -> RGB conversion, I get 255/204/0 (vs 205/204/0).

 

I've made tests both on Mac an PC, with PS 2021, same results.

 

I just don't find the same values as I get with InDesign when using SnapshotUtilsEx... whatever the 'intent' I use (Perceptual/Relative/Absolute/Saturation)...

 

Well... I think this will remain a mystery... I think only Adobe devs' could explain what is really done when using SnapshotUtilsEx...

 

J.

 

 

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LEGEND ,
Aug 18, 2021 Aug 18, 2021

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A small point: JPEG is lossy, as you know, meaning colours can change each time an image is saved and reopened. Using only one colour would make no difference, it can still change (or produce multiple similar colours).

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Adobe Community Professional ,
Aug 18, 2021 Aug 18, 2021

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Create a CMYK PS file.

Fill it with 0/20/100/0 color

Convert into sRBG (Adobe( ACE) / Perception / Use black point compensation) => RVB 255/204/0

Convert into FOGRA39 (same settings) => CMYK 5/22/91/0

Convert into sRGB => 243/197/31.

 

Hi @Jacques TRIPOZ When making round trip CMYK>RGB>CMYK>RGB conversions you would have to consider the size of the destination RGB space. In your example the starting FOGRA39 0|20|100|0 CMYK value is not inside of the relatively small sRGB gamut, and I think that would account for the significantly different 2nd RGB values.

 

If you compare the sRGB and FOGRA39 spaces they actually intersect—FOGRA39 is not completely inside of the sRGB space. A good portion of the yellow/orange gamut is out-of-gamut to sRGB, here’s a comparison of sRGB (white) with FOGRA39 (color)

 

Screen Shot 18.png

 

If you try a round trip with a color that is inside of both gamuts using Relative Colorimetric you should get a match. With the in-gamut 60|0|60|0 I get 111|188|133 for both the first and second RGB values.

 

Alternatively you could try a wide gamut RGB space like ProPhoto RGB as the destination—it contains 99% of the FOGRA39 CMYK space:

 

Screen Shot 19.png

 

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Participant ,
Aug 18, 2021 Aug 18, 2021

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Hi Rob,

Interesting !

I'll give a try with the wide-gamut RGB. My first concern is not the first CMYK => RGB conversion, but what I'm looking for is to have the 2 RGBs as similar as possible.

Thx !

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Adobe Community Professional ,
Aug 18, 2021 Aug 18, 2021

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Also, try using the Relative Colorimetric intent. It attempts to bring color into gamut with as little appearance change as possible. Perceptual tries to avoid converting slightly different out-of-gamut colors as the same color in the smaller space—for example if you cared more about shadow details than color appearance.

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