Rich Black for Black and White Photographic Images?

[achasin]

I'm currently working on printing a zine containing some of my black and white photographs.  I printed a test zine with the printing company I'm working with and the images look dull and flat - no deep blacks to speak of.  The zine was printed on a digital press and I used the CMYK color profile provided by the printing company (Coated GRACoL 2006 (ISO 12647-2:2004)) in my images/InDesign file. 

To remedy the lack of deep blacks, the printer suggested that I use Rich Black (CMYK = 30% 30% 30% 100%) rather than Standard Black.  I understand how to create a Rich Black swatch in InDesign and apply it to something like a solid black background, but I don't really understand how to apply that swatch to my photographs. 

Can anyone suggest how I might go about using the suggested Rich Black to produce deep blacks in my printed photos, using InDesign and/or Photoshop?

Thanks in advance.

[James Gifford—NitroPress]

I think @rob day is the go-to user here for this issue.

It's been a while since I did high-quality offset work, but I think images have to be prepared for rich black output — I am not sure if simple export from InDesign will remap the colors from image files. But I could be wrong; I know the PDF export process has endless levers for this kind of control.

[Derek Cross]

Maybe worth posting in the Photoshop forum.

[rob day]

but I don't really understand how to apply that swatch to my photographs.

Hi @achasin , I’m assuming by black and white photos you mean you are placing Grayscales?

As long as the placed grayscales have no transparency, you can Direct Select the image and apply any color or Swatch. If you turn on Separation Preview you can view the output values when you mouse over the image.

By default a placed grayscale with no transparency gets the [Black] Swatch applied. Here Separation Preview shows the output of the 100K patch in my control ramp as 0|0|0|100. You might check the black point of your grayscale images and make sure your black point is really hitting 100%—that could be the reason for the flat grayscale output:

The middle image has my Rich Black Swatch applied 65|50|50|100. Note that usually you want there to be some extra Cyan in the mix if you want a neutral gray:

Also if you assign an RGB black the conversion to CMYK on Export will be to the blackest black point allowed by the GRACoL profile. Note that the RGB black has to be something more than 0|0|0 in order to force the conversion:

[achasin]

@rob day Thanks so much for the reply.

Showing my ignorance here, but when you say 'placing Grayscales' I assume you mean importing Grayscale images into InDesign and placing them onto a page, correct?  The process I followed (which may not have been the best choice) was to take my original RGB image files, convert them to CMYK using the printer's supplied profile, and then insert them into my InDesign document.  So they weren't Grayscale images when I brought them into InDesign.  I have my RGB originals and I can convert them to Grayscale first before applying the Rich Black swatch, if that's a better option.  Or does explicitly selecting the Rich Black swatch for a CMYK image also apply the swatch? 

Re: the black point, what is the best way I can check to see if it is hitting 100%?  I tried to use the Curves panel in Photoshop to check this and the deepest blacks did show up in the clipping preview, but I didn't see a way to view the black point as a percentage.  Again, showing my ignorance of Photoshop here.

One more silly question about the way Photoshop applies these swatches - if I create a Rich Black swatch (for example) and select it after direct selecting the image in my InDesign document, what is the algorithm used by Photoshop to apply it? i.e. which values in the image are replaced with Rich Black?

Thanks again for all your help.

[rob day]

To follow your printers suggestion of applying a rich black swatch to the image, it would have to be done to a placed grayscale in InDesign—you can’t apply a color swatch to an RGB or CMYK image.

Can you share an example of your original RGB image and the converted CMYK image you placed in InDesign? Also, did you supply the printer with a PDF? If so, can you also share the PDF?

[achasin]

Here is an example of an RGB image and the converted CMYK image I placed into InDesign.  The Adobe Community site wouldn't let me attach TIFF files so I'm sharing links to the two images:

RGB Image 
CMYK Image 

I did supply the printer with a PDF but it's very large and will be unwieldy to share.  I can create and share a smaller version with just a couple of images in it if you think that will be helpful.

[rob day]

I’m not sure what the printer is talking about, the CMYK file you shared has a maxed out black point—the shadow I’m sampling below is 86|75|69|94, which is near GRACoL’s maximum total ink of 330%, so you couldn’t get it much denser (the highlights are blown out they are near 0|0|0|0 CMYK). If these are the values exported to your PDF, it sounds like there was an additional conversion at the printer.

What preset did you Export with? By digital do you mean this is some kind of composite short run press and not separated offset printing?

If it is a composite printer, you might try running a proof of the B&W RGB version—place the RGB image and Export to a PDF/X-4 with no color conversion. Coated GRACoL is an offset press profile and composite printers often do better with profiled RGB images, which should get converted to the printer output space by the composite driver or RIP.

[achasin]

Yeah, something doesn't make sense to me either.  The PDF proof I was sent looked fine - pretty much exactly what I see in InDesign, so I'm not sure why the final printed output looks so different.

I exported the PDF from InDesign using a slightly modified vesrsion of the Press Quality preset, but with a couple of modifications dictated by the printing company:

Yes, it's a short run press, not offset printing.

[rob day]

You might want to double check the CMYK values in the PDF you sent. Use AcrobatPro’s Output Preview to check the blacks—with offfset printing 86|75|69|94 would print blacker than 30|30|30|100.

If it were me I would get them to proof a page exported to default PDF/X-4 with an RGB image, and see if that gets the press black point.

[achasin]

I just spot checked the CMYK values in my PDF using Acrobat Pro and they are the same as those in my CMYK image files.  So I have to conclude that either my expectations of what these images should look like in print are unrealistic or there is some further transformation happening after the PDF file has been generated.

[rob day]

or there is some further transformation happening after the PDF file has been generated.

Yes, that would be expected with most composite printing vs. separated offset printing.

Either the printer doesn’t have a complete grip on CM, or they want you to work in a CMYK space so that you are not using out-of-gamut RGB colors and expecting them to be printable. The better way to do that would be to simply turn on Overprinr Preview, which previews RGB color in the document’s CMYK space.

If there is always going to be a color conversion in the driver or RIP, it doesn’t make much sense to convert to a random CMYK space—it would just be an extra conversion. If you do provide RGB there should be a source RGB profile embedded—the default PDF/X-4 preset with No Color Conversion would do that—your printers preset, which doesn‘t include profiles would not.

[achasin]

@rob day Thanks again for the response.  I've learned a lot from your posts.

One odd thing that I have noticed that you might be able to clarify for me - when I am in InDesign and I select 'Proof Colors' I see the blacks shift towards grey.  I'm not sure why that would be the case given that my images are using the same color profile as the target output profile.  Maybe I've got something setup incorrectly in my Proof settings or Appearance of Black settings.

The first image below is before Proof Colors, the second is after Proof Colors.  Hopefully the differences are visible on screen.

As displayed in InDesign
As Displayed during Proof Colors

[rob day]

You would only use Proof Colors when you want to soft proof for something other than Document CMYK—e.g. your document CMYK profile is Coated GRACoL and you want to soft proof for a press running US Sheetfed Coated.

When the output destination is Document CMYK all you have to do is turn on Overprint Preview. In your case Overprint Preview is the soft proof for Coated GRACoL 2006.

[rob day]

Also, if you look at the washed out press sheet under a magnifier, do you see a CMYK halftone dot pattern or is it a black only halftone?

[achasin]

I actually did that the other day.  When looking under a loupe I confirmed that It is black only since it was printed Grayscale, not color. 

Hmm, I see I may have failed to mention that fact earlier, my apologies.  I selected the printer's Grayscale printing option rather than 4-color CMYK since the images are all black and white.  

[rob day]

I actually did that the other day. When looking under a loupe I confirmed that It is black only since it was printed Grayscale, not color.

I missed this post. I thought you were placing CMYK—how did the placed CMYK file get converted to grayscale when you exported the PDF? You are Exporting and not Printing/Distilling the PDF right?

[achasin]

@rob day I didn't convert to grayscale at any point.  When you define a print job with the printer you choose either 'Grayscale' or 'Color' for the job.  Since all of my images/text are black and white, I chose (perhaps unwisely) 'Grayscale'.  According to the printer's web site:

If you are printing in black and white only, then you are printing with just the K ink. We won't print with the Cyan, Magenta, and Yellow inks.
...
Printed standard black produced using only the K ink, however, will not appear as intensely as Rich Black, which combines Cyan, Magenta, Yellow, and Black, offering more vivid results.

So, presumably, they are doing a conversion to grayscale from CMYK at print time for 'Grayscale' print jobs.  I don't know exactly how they do that conversion, however.

[rob day]

Since all of my images/text are black and white, I chose (perhaps unwisely) 'Grayscale'.

Yes, that‘s likely your problem—you asked them to convert your CMYK images to grayscale and they did.

InDesign’s Overprint Preview soft proofs the expected difference:

[achasin]

I guess printing in Grayscale was probably not a good choice.  

OK, so I'm unclear of the correct approach.  Should I leave my black and white images as RGB, import them to my InDesign document , export a PDF in CMYK using the printer's profile, and print the project as a color job?  Or should I use the Rich Black swatch instead of the default black as the printer suggested?  I'm unclear how Rich Black is a solution if using the Rich Black swatch results in less dense blacks.

I'm also still a bit confused about applying the Rich Black swatch.  As you said, that can only be applied to a grayscale image.  However, the printing company told me not to convert my images to grayscale in Photoshop but to convert them to CMYK in Photoshop before bringing them into InDesign.  So I don't see how I could use the Rich Black swatch if the images come into InDesign as CMYK. 

FYI, when I convert the images to grayscale in Photoshop, bring them into InDesign, apply the Rich Black Swatch to them, and then export a PDF from InDesign using the printer's color profile, my PDF does not look good - the images look murky with muddy grey blacks.  FWIW, I'm using the 'Simulate Black Ink' in Acrobat Pro when viewing the PDF. 

Apologies for all of the silly questions.  This is obviously the first time I've tried to print my photographs on paper this way.   I'm a darkroom printer and normally make silver gelatin prints of my photographs.  None of these issues arise in that context, although that has its own set of problems 🙂 

[rob day]

I'm unclear how Rich Black is a solution if using the Rich Black swatch results in less dense blacks.

It isn’t—I’m guessing the printer did not look at your PDF and assumed you had sunbmitted a color job with grayscales images in the PDF.

I would try resubmitting your PDF with the Coated GRACoL CMYK images as a color job, so the printer does not convert to grayscale at output, and get a proof.

[achasin]

@rob day Thanks again, that's what I'm going to do. 

Do I need to convert to CMYK GRACol CMYK in Photoshop before linking the images in InDesign, or can I link to my RGB images and let InDesign perform the conversion to CMYK when I export the PDF?  I think someone else in this very long thread suggested that I could let InDesign perform the conversion, but I'm not sure if there's any difference if it's done in PS or ID.

[rob day]

I think someone else in this very long thread suggested that I could let InDesign perform the conversion, but I'm not sure if there's any difference if it's done in PS or ID.

You can, but the PDF result will be the same assuming the destination is still the Coated GRACoL profile. In the end it’s your instruction to convert the CMYK images to grayscale that is likely causing the problem.

[achasin]

In the end it’s your instruction to convert the CMYK images to grayscale that is likely causing the problem.

OK. I guess it's good that it's something I can probably fix easily on my end.  I am a bit baffled as to why the printer didn't simply tell me this rather than suggesting Rich Black as a solution.  But I'll give this a go and see what I end up with.

Thanks for all your help @rob day , greatly appreciated.

[rob day]

I am a bit baffled as to why the printer didn't simply tell me this

Is this an online printer?

With online printers job submission is normally automated—there is no customer service rep, so no one is going to actually preflight the PDF. For that you get a better price, but it’s harder to navigate without print experience or knowledge.