New in Adobe InDesign 2025 is the ability to set math content using MathML. When you create math content this way, equations are inserted as SVG anchored objects. Since SVG is a web format, it does not support CMYK color. This means that math content will be rendered in RGB black, which will separate into rich black on press, potentially resulting in poor commercial print quality.
You can see that math content will print in all four inks in the Separations Preview panel (Window > Output > Separations Preview).
If there is any misregistration on press, other inks besides black will be visible, resulting in a less than crisp appearance of the math content.
One way to prevent this from happening is to use a FixUp in Adobe Acrobat.
Using Adobe Acrobat to Fix RGB Math Content
To confirm the presence of RGB math content in a PDF, open the Output Preview Panel from the Print Production Tools in Adobe Acrobat. Choose Object Inspector from the Preview pop-up menu, then click on an equation.
In the Print Production tools, click Preflight. Click the wrench button to select a single FixUp and type RGB to filter the list down to just the FixUps with that term in the name. Double-click the FixUp for converting RGB Black to CMYK Black.
You will be prompted to save a new copy of the PDF. You can go back to the Output Preview to confirm the problem was fixed and be assured that your math content will print in black ink only.
Tip: When using a FixUp, I always recommend testing on a few pages to confirm its working as intended.
This article was last modified on October 22, 2024
This article was first published on October 18, 2024
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Hi together,
one thing to add is that in case the expression is positioned onto a colored object like the fill of a text frame or the fill of a table text cell, one should make sure in Acrobat Pro that the resulting CMYK Black is overprinting.
Regards,
Uwe Laubender
( Adobe Community Expert )
And yes, the conversion of RGB Black [0,0,0] to CMYK [0,0,0,100] does work with a PDF/X-4 exported PDF with no color conversion. It does not, when the PDF is exported as PDF/X-1a.
Regards,
Uwe Laubender
( Adobe Community Expert )
That’s no wonder, because PDF/X-1a does not support RGB colors.
Regards,
Uwe Laubender
( Adobe Community Expert )
To get an RGB Black at 0, 0, 0, you need NOT to use [Black] or custom black for your Math ML object. Use an RGB Swatch from the start. Without this James’s Preflight fix won’t work.
Hi Jean-Claude, when picking the [Black] CMYK swatch the Mathematical Equations in the Exported PDF are RGB (0 0 0). At least those are the results I’m getting.
Which PDF setting are you using to create it?
I get this: Color Values = [0.13700, 0.12200, 0.12500]
with HighQuality, PDFx4 and even Interactif.
Good point Jean-Claude, depending on what setting you use when exporting a PDF, you will get different values, PDF/X-1a vs PDF/X-4 for example. I used PDF/X-4 leaving the default color settings to No Color Conversion. I get RGB values of 0 0 0 in the exported PDF.
To get RGB 0 0 0, we indeed need to export without color conversion.
But I always get a dirty black even with PDF/X-4.
I also notice when I edit the Math ML that the “mathcolor” is not #000000 (for black) but #262425″. I am wondering why.