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Converted black and white RGB photos to grayscale loose contrast in InDesign

Community Beginner ,
Jul 17, 2020

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For a book with grayscale and color photos I want to convert the original black and white RGB files to grayscale. When I convert the RGB file of a black and white photo to grayscale in Photoshop both files look identical and have the same values:

 

01_photoshop_values_rgb_file.png

The original RGB file

 

02_photoshop_values_grayscale_file.png

The resulting grayscale file (notice the color values top right in both screenshots)

 

Imported in InDesign they suddenly look different: the grayscale photo appears dull compared to the RGB original:

03_indesign_both_files_display_differently.png

 

That doesn’t change when I export from InDesign to a print PDF. The color values show, that in the grayscale file the spot above the house has changed from 23% to 32%! The RGB file has – as expected – changed to corresponding CMYK values (what I want to avoid for the print process).

 

06_indesign_export_settings.png

My InDesign export settings.

 

05_acrobat_values_grayscale_file.png

The color values of the imported grayscale file in the resulting print PDF.

 

04_acrobat_values_rgb_file.png

The color values of the imported RGB file in the resulting print PDF.

 

Does anyone know how I can preserve the contrast and values of the grayscale file when importing to InDesign (and exproting to a print PDF)?

Adobe Community Professional
Correct answer by rob day | Adobe Community Professional

Your trick didn’t work as expected: By deleting the a and b channel in the lab color space the image instantly got a lot (!) lighter (former deep black areas went to a dark grey).

 

I don’t think it has to be that complex—a simple RGB to Grayscale conversion using the correct profiles should work. Like this:

 

Starting with an RGB image, Photoshp’s Convert to Profile with the Destination set to Black Ink - ISO Coated v2 300%

 

Screen Shot 18.png

 

The converted Grayscale sampled:

Screen Shot 19.png

 

InDesign’s Separation Preview shows a matching output value on the K plate:

 

Screen Shot 20.png

 

Exported to default PDF/X-4. The previews and output values match in all 3 applications.

 

Screen Shot 21.png

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Converted black and white RGB photos to grayscale loose contrast in InDesign

Community Beginner ,
Jul 17, 2020

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For a book with grayscale and color photos I want to convert the original black and white RGB files to grayscale. When I convert the RGB file of a black and white photo to grayscale in Photoshop both files look identical and have the same values:

 

01_photoshop_values_rgb_file.png

The original RGB file

 

02_photoshop_values_grayscale_file.png

The resulting grayscale file (notice the color values top right in both screenshots)

 

Imported in InDesign they suddenly look different: the grayscale photo appears dull compared to the RGB original:

03_indesign_both_files_display_differently.png

 

That doesn’t change when I export from InDesign to a print PDF. The color values show, that in the grayscale file the spot above the house has changed from 23% to 32%! The RGB file has – as expected – changed to corresponding CMYK values (what I want to avoid for the print process).

 

06_indesign_export_settings.png

My InDesign export settings.

 

05_acrobat_values_grayscale_file.png

The color values of the imported grayscale file in the resulting print PDF.

 

04_acrobat_values_rgb_file.png

The color values of the imported RGB file in the resulting print PDF.

 

Does anyone know how I can preserve the contrast and values of the grayscale file when importing to InDesign (and exproting to a print PDF)?

Adobe Community Professional
Correct answer by rob day | Adobe Community Professional

Your trick didn’t work as expected: By deleting the a and b channel in the lab color space the image instantly got a lot (!) lighter (former deep black areas went to a dark grey).

 

I don’t think it has to be that complex—a simple RGB to Grayscale conversion using the correct profiles should work. Like this:

 

Starting with an RGB image, Photoshp’s Convert to Profile with the Destination set to Black Ink - ISO Coated v2 300%

 

Screen Shot 18.png

 

The converted Grayscale sampled:

Screen Shot 19.png

 

InDesign’s Separation Preview shows a matching output value on the K plate:

 

Screen Shot 20.png

 

Exported to default PDF/X-4. The previews and output values match in all 3 applications.

 

Screen Shot 21.png

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Jul 17, 2020 0
Adobe Community Professional ,
Jul 17, 2020

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That is what profiles do, so why not convert to 'CMYK', in this that is only K, with the correct profile (greyscale with wanted profile) in Photoshop and place that in InDesign?

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Community Beginner ,
Jul 17, 2020

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Thanks for your quick reply. I am not sure, if I am getting you right. My questions was: Why is InDesign changing the appearance and values of an imported grayscale file (which handled Photoshop right)? Color profiles are synced with Bridge.

 

Converting a black and white photo RGB file to CMYK in Photoshop results in exactly what InDesign is giving me: values in all color plates (a "not wanted" color separation of a black and white). The black color plate in this CMYK file is not identical to the black and white photo.

 

My client converted his photos in Lightroom to black and white, so I am getting RGB files of black and white photos. My printer advises me to give him a print PDF with the photos just on the black (key) plate.

 

 

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Adobe Community Professional ,
Jul 17, 2020

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Actually, InDesign isn't changing your placed image at all.

 

What it's doing is providing you a (mostly) accurate simulation of what your job will look like when it comes off press. It's bringing the disappointment of print production results right up front where you can see it early in the process, and account for it, rather than you getting a rude surprise when the job comes off the press. And telling you while you're creating the document that you need to correct for them now or you'll get the results you see onscreen at the end of the process.

 

If you're not happy with what you see will happen at the end of the process, you need to correct those issues before you get there. There are books, courses and careers dealing with the specifics, tips and techniques of image color correction. But the following link is a good place to get started. Dive deep into the rabbit hole from here:

 

Color and tonal correction with Adobe Photoshop

 

Hope this helps,

 

Randy

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Adobe Community Professional ,
Jul 17, 2020

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There's a reason for this:

 

Output values for InDesign color settings. Using your Euro ISO coated stock color settings, you can not only count on 20% dot gain (where "25%" would reproduce at 25% + 2.5% + 2.5%, with InDesign indicating that your "25%" would print at least 30% on press without image correction, but you can also account for the general "dulling" you see as there's compression of the dynamic range within the lightest and darkest shades you can print (highlight dot/shadow dot). The settings you see as you save your PDF from InDesign are directly copied from the color settings you have set for your InDesign document.

 

No compensation for the color settings within Photoshop. Franz is steering you right that you should compensate for the end result directly from Photoshop to preclude surprises. Start by using the same settings in Photoshop that you're accounting for within InDesign. But I can also offer you another trick that'll minimize the "dulling" effect that is getting you down.

 

Try this:

 

  1. Make a copy of the original image in Photoshop. You always want to be working with copies of the original file for any image corrections, as that preserves the original image if your experiments should go awry.
  2. Rather than change the image from RGB color mode directly to Grayscale, change it to the Lab Color space. You won't at first see much difference, but trust me, you will see much difference — and I believe a difference you'll prefer — by the time we're done with it.
  3. Open the Channels panel. Delete the "a" and "b" channels by first selecting them, then clicking on the little trash can in the lower-right corner of the panel. You should get the impression of higher contrast (or slightly higher contrast) like your original RGB shot.
  4. Now go back to your Image>Mode menu command. You'll see that your image is now shown as Indexed Color... and this is the time to change it to Grayscale. You may note that your image darkens slightly, but when you place it in InDesign, you won't see the dulling effect like you were getting in your InDesign document. If you match up the color settings in Photoshop with the settings you're using with InDesign, you shouldn't see any surprises at all.

 

This will hopefully get you results more like you'd expect.

 

Nice art, by the way. Please let us know how this works for you, and good luck with your book.

 

Randy

 

 

 

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Adobe Community Professional ,
Jul 17, 2020

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Why is it that in English I always get called FranZ, and not FranS?? 😉

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Community Beginner ,
Jul 17, 2020

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Thank you very much for your detailed answer, Randy! I understand that my problem has to do with the color settings, although I don’t have a clue how to adjust them, because everything is synced perfectly (so it seems to me).

 

Your trick didn’t work as expected: By deleting the a and b channel in the lab color space the image instantly got a lot (!) lighter (former deep black areas went to a dark grey).

 

I am going to dive deep into the rabbit hole of "color and tonal correction in Photoshop" now, as you suggested 😉

 

Thanks again for your help!

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Adobe Community Professional ,
Jul 17, 2020

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The lightening is to be expected, but the contrast is there. And if you want to adjust it to make it darker, manipulating Levels... and Curves... options through the Image>Adjustments menu command can get you where you want to be. You'll see both those options discussed in cursory detail from the link I provided, and also by researching them specifically through a search in the support database.

 

Just remember to work with copies of the original image. As I said above, if your experiments should go awry, working with copies of original file limits the damage to time you spent experimenting.

 

As to the color settings, start by talking with the print house which will be printing your book. If available, you want to be using the house's specific recommended settings, rather than adjusting any of them on your own. Color settings establish the correct baseline before you apply tonal changes to the images. You don't want to be messing with the color settings — which right now are set as ISO Coated v2 300% (ECI) — within InDesign. If that's the baseline you're going to use, you want to use the exact same color setting in Photoshop before working with your images. If your printer provides a custom set, use those instead.

 

In any case, they're not to be trifled with after establishing the same, consistent baseline across all your Adobe applications for any given project. And if you need to change those settings for a different project, first choose the correct profile for the job and then change to that new, correct profile across all your Adobe applications to preclude surprises. If you're going to be fiddling with color correction, this is 1) entirely necessary, 2) critically important and 3) absolutely the first thing you want to do before you even start tonal correction in your images.

 

You can read more about this (in Photoshop) here:

 

Color Profiles in Adobe Photoshop

 

The rules apply just as much in other Adobe graphics applications. The link above gives one of the best overviews of what color profiles are and why they're important.

 

Good luck,

 

Randy

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Adobe Community Professional ,
Jul 17, 2020

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Your trick didn’t work as expected: By deleting the a and b channel in the lab color space the image instantly got a lot (!) lighter (former deep black areas went to a dark grey).

 

I don’t think it has to be that complex—a simple RGB to Grayscale conversion using the correct profiles should work. Like this:

 

Starting with an RGB image, Photoshp’s Convert to Profile with the Destination set to Black Ink - ISO Coated v2 300%

 

Screen Shot 18.png

 

The converted Grayscale sampled:

Screen Shot 19.png

 

InDesign’s Separation Preview shows a matching output value on the K plate:

 

Screen Shot 20.png

 

Exported to default PDF/X-4. The previews and output values match in all 3 applications.

 

Screen Shot 21.png

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Community Beginner ,
Jul 17, 2020

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Thanks a lot, Rob, that looks promising! I’ll give it a try on Monday when I’m back in the office. I learned a lot today 😉

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Adobe Community Professional ,
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InDesign does not have a grayscale space, so gray values get displayed as if they are on the InDesign CMYK black plate when Overprint Preview is turned on.

 

The gray output values you get on a conversion from RGB to Grayscale in Photoshop depend on the source RGB profile and the chosen destination Gray profile—you would get different values if the destination gray profile is the default 20% Dot Gain vs. Gamma 2.2 profile.

 

The default 20% Dot Gain profile causes a lot of confusion, because it would not be the correct profile if your InDesign CMYK output destination is ISO Coated V2 300% (shown in your screen capture). The destination Gray profile used in Photoshop should be the matching Black Ink-ISO Coated V2 300% black ink profile.

 

These threads have more on how to color manage grayscales and how to create Black Ink profiles from a CMYK profile:

 

https://community.adobe.com/t5/indesign/dot-gain-or-gray-gamma/td-p/8365606?page=1

 

https://community.adobe.com/t5/indesign/exporting-rgb-cmyk-and-grayscale-to-print-pdf/m-p/10990825?p...

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Community Beginner ,
Jul 20, 2020

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Thanks again, Rob, I just did several tests and your screenshots in combination with the provided links helped a lot. I changed my working space’s gray to "Black ink – ISO coated v2 300%" and now it works as expected. Though I had to learn with a little bit of trial and error, that I have to start new (as Randy thankfully pointed out): Saving the new working spaces (with "Black ink – ..."), be sure to use it in all Adobe applications, start a new InDesign document, making a new file from the RGB original and converting it to "Black ink – ...", importing it in the InDesign Document – and setting the separation preview (without the preview turned on it looked wrong, but the output was correct). That made sure the gray values remained the same in all apps.

Thank you to you Adobe experts who helped me with this issue, that was perfect support!

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Adobe Community Professional ,
Jul 20, 2020

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be sure to use it in all Adobe applications

A few other things to note, InDesign doesn’t have a Working Gray space, so you can’t assign a document gray profile, or choose a Gray Working Space in Color Settings the way you can in Photoshop.

 

An embedded Gray profile will show in the Links panel, but it is ignored by InDesign—the InDesign CMYK profile is used to display the grayscale on the black plate when Overprint or Separation Preview are turned on. The grayscale will always export with its output values unchanged as long as it is exported as a grayscale. If the document is exported to a CMYK destiantion that conflicts with the doc’s assigned profile, the grayscale will get converted to 4-color CMYK.

 

without the preview turned on it looked wrong, but the output was correct

ID has two soft proofing modes for grayscale images. With Oveprint/Separation Preview on you get a color managed print preview using the assigned CMYK output profile. With OP Off, grayscales preview as sGray (2.2 Gamma)—if you were designing for screen output you would leave Overprint off.

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Adobe Community Professional ,
Jul 20, 2020

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>The grayscale will always export with its output values unchanged as long as it is exported as a grayscale

Be aware that Rob means the K version (the 'CMYK' version so to speak) and not any still RGB greyscale!

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Jul 20, 2020

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Yes the Links panel can have some confusing info for Grayscale images. If the grayscale has an embedded profile it shows in the links panel and one might assume that it is being used for the display of the image, which would be the case for RGB or CMYK images, but it is actually ignored.

 

You can see the CMYK profile assignment handles the grayscale’s preview by changing the assignment. Change the assignment to a newsprint profile, and the preview loses contrast, which is what would happen on newsprint.

 

Screen Shot 17.pngScreen Shot 18.png

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Community Beginner ,
Jul 21, 2020

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This thread was an amazing in-depth "behind the scenes" view of color management for grayscale images in InDesign!

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Jul 21, 2020 0