text colors not displaying properly in the PDF file

[rschlegel]

I set a single text word in a blue spot color, then, in a sparate text block, inserted a type glyph and placed it beneath the blue text word, and set the glyph in red. After creating a PDF file, both elements are set in red. 

What happened?

[Lukas Engqvist]

It is hard to tell from your brief description. You can see spot colours both in Acrobat and in Indesign. Both have panels for viewing separations. Note that spot colours are dependent on name conventions so the names of the spot colour may be part of the problem. Also what software are you viewing the PDF file, not all PDF viewers have the correct support for spot colours (Apple Preview and Microsoft Edge are among those PDF viewers that do not display spot colours correctly)

[rschlegel]

I think you are right in diagnosing the issue.

The problem began when I changed the blue colour. I want to change the blue
to one that is most reliable across devices.


So, which type of color definition would you recommend to assure reliable
display across various PDF viewers and book reader apps?

[Lukas Engqvist]

First you must be aware that reader apps can sometimes over ride decisions that you make as designer. 

If you are wanting to go across screens I would say you should use RGB and more specifically sRGB. Blue is a hard colour to reproduce consistently accross devices and "pure" RGB blue is closer to what we traditionally would call Indigo… so it's verging on a lingustic problem.

sRGB has limitations, you will not access all the colours available in CMYK (pure yellow and cyan tones are underrepresented), but if you will choose AdobeRGB you will most likely have a greater variation (since devices that do not support calibration assume sRGB as the fallback colour space) 

You can also use LAB which is device independant, and to be consistent use the swatches, the risk with LAB is that you can choose colours that are out of gamut meaning that they will not be reproducable on some devies or print methods. In InDesign all swatches are "global" meaning that objects are linked to the colour so that editing the swatch will uppdate where the colour is applied. 

If devices/screens are where you will be viewing final work it is good practice to start with a web or screen document and/or confirm that Transparency Flattening is in RGB (This affects how blend modes like multiply or screen works).

If you are planning to also print you may be better to chose to work in CMYK and that has to do with getting black to be K only so that you do not blur text or fine strokes. 

[rob day]

to assure reliable display across various PDF viewers and book reader apps?

Hi @rschlegel , Unless to final output is to an offset press capable of running custom color separations and you want to pay more for an extra plate, then all of your colors should be defined as Color Type Process.

If the PDF is for screen viewing and not print, set the Export>Output Tab Destination to sRGB which is the default color space for modern browsers.

[Lukas Engqvist]

Many modern workflows and digital presses have tables for optimal conversion of spot colours, so I would not agree that you must have process colours beacuse of the printer, although it is best to check with print provider. But I do agree that it may be problem with spot colours but my argument is because of the lack of support in screen readers.

[rob day]

digital presses have tables for optimal conversion of spot colours

Hi Lukas, Yes if it’s from a known library like Pantone, and there is communication with the printer, but not from a randomly created "Blue" color set as Spot Color Type.

For universal screen viewing, dumbing down the color to flattened process sRGB is going to be more reliable—how various browsers handle a Lab or CMYK defined spot colors inside of a PDF could vary. An Interactive PDF would convert all Spots to sRGB Process color—with Print PDFs you have to either set the Spots to Process or use Ink Manager to make the conversion.