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I've spent a long time figuring this out, tried to print from a bunch of different programs with all the profiles and setting I could find, to no avail.
Situation: I have a multi-page PDF or whatever else file with everything in CMYK. I want to convert it to gray scale. Result - all black levels of every single object are changed. 100% black becomes like 92%, 80% becomes 75%, and so on. Every single profile does this, resulting in unusable files, since 100% text and 92% text are visibly very different.
Is there any type of conversion which does not touch black-only colours in CMYK->Grayscale conversion?
I have Acrobat XI Pro with PitStop Pro installed.
Shajirr
Posted 2018-03-12T13:35:13.660
Reputation: 89
If you have PhotoShop, try it from inside Photoshop. Photoshop can open PDF files too, and is great for conversions. – LPChip – 2018-03-12T13:44:55.953
I should have mentioned that I need this for books and other types of multi-page documents. So no Photoshop. – Shajirr – 2018-03-12T13:55:06.307
Have you tried the solutions in How to convert PDF to Grayscale?
– DavidPostill – 2018-03-12T13:58:15.463That thred doesn't mention anything about preserving black levels during conversion, which is what my problem is – Shajirr – 2018-03-12T14:04:29.687
2Don't forget the limitations of CMYK. CMYK color scheme is missing some colors due to how CMYK mix compared to RGB, so when you convert to grayscale, which essentially are colors and not truly black, it will have to try to get to the same color using CMYK and simply may not be able to, resulting in lighter colors. If you do it in one page with photoshop to test, you can at least verify if the CMYK limit is not what stops you. – LPChip – 2018-03-12T14:08:42.037
Limitations of colour conversion that you mentioned are not applied in case of pure-black colours, since it should be a direct value transfer from 0 CMY 100 B to 100% black in Grayscale. B&W only physical printers have no problem converting such CMYK colours to be printed correctly, but when I do the conversion manually I get the problem described above. – Shajirr – 2018-03-12T14:45:23.157
This problem exists because all these conversions try to differentiate between rich black and pure black by reducing black level of every pure black colour. Which is exactly what I don't want to be happening. – Shajirr – 2018-03-12T14:53:12.260
The best solution is to avoid conversion in the first place, since there is (arguably) very unlikely to be a satisfying solution regarding tints. I am guessing you don't have the original materials the PDFs were composed from, but I would at least consider contacting whomever you got the PDFs from and asking them for proper grayscale versions. – Anaksunaman – 2018-03-13T07:34:39.487