PDFs in color or mono?

I have always gotten into the habit of exporting my PDFs in color, since I occasionally need to use the transparency trick, and rather than thinking about it each time, I’ve just set color as the default.

Now a zillion PDFs later, I’m realizing that this color export has been the source of so many pre-flight errors flagged by printers. It seems (although I don’t know for sure) that, while digital printing doesn’t care, offset printing does. I’m trying to decide whether I should continue to make the conversion to B/W in a DTP in the final step before submission to the printer, or whether I should switch to exporting in mono, since transparent objects in Dorico are rare for me these days.

Is there any practical difference between a CMY black (which I assume “color” is) and a mono black?

Besides revealing transparent objects, would there be any perceptible difference between a mono and a color export?

What I can tell you is that every once in a while I put a graphic into one of my worship aids, and switching to a greyscale colorspace (rather than B&W) has stung me once or twice, where I thought something was true black, but it wasn’t, so it didn’t print that way. Consequently, I strive to do mono exports as much as possible, but it’s very rare that I try and hide things by changing opacity. Of course you can always just genuinely delete those things if you’re in AP anyway.

As usual, ‘it depends’.

In CMYK, a black coloured object can be 100% solid Black ink. However, it can also be represented as, say, 80% Black ink and some smaller percentages of the other inks. This can notably occur when converting colours described in RGB to a CMYK equivalent.

You may remember an issue with Finale outputting PDFs that ended up as 80% grey for this very reason – obviously, if the printing press is only using a single ink, then the CMY information will be discarded.

I’ve not checked recently, but I’d be surprised if Dorico’s black DIDN’T come out as 100% K in a CMYK colourspace.

Arguably, a single-colour colourspace is probably safest if you’re working with a single colour.

1 Like

Thanks. I wonder if this is something @dspreadbury could confirm. If indeed Dorico does create composite blacks that are no different from true blacks, I’ll probably just continue exporting in color from Dorico as I’ve been, set my DTP profile to CMYK, and convert to B/W on final export.

1 Like

If you export in mono, you will get true (key) black. If you export in colour, you will get rich black. Whether this matters depends entirely on the final output device.

You mean a particular printer could render them differently?

“Printer” covers a multitude of sins. Are you talking about offset printing using CMYK colour separation, or an imagesetter, or a big workgroup laser printer, a home laser or inkjet printer, or something else?

In this case, offset printing on a rather large press.

If you’re printing directly from Dorico’s PDFs, then you should definitely ensure you choose Mono so you don’t end up with rich black. But if you are post-processing in another application that has proper support for handling colour for offset printers, then that application should be able to guarantee what inks are needed.

1 Like

Thanks Daniel.