Known Participant

Question

Rich Black for Black and White Photographic Images?

Forum|Forum|2 years ago
February 4, 2024
4 replies
5198 views

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.

Scott Falkner

Community Expert

I suggest a duotone or simulated duotone instead.

https://www.adobe.com/ca/creativecloud/photography/discover/duotone-effect.html

rob day

Community Expert

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:

A

achasinAuthor

Known Participant

@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

Community Expert

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.

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.

Derek Cross

Community Expert

Maybe worth posting in the Photoshop forum.

James Gifford—NitroPress

Legend

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.

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