I'm having a strange color display issue whenever I convert an ad I built in Indesign to a PDF for output on newsprint using the SNAP 2007 preset.
Is the SNAP profile assigned to your ID document—check Edit>Assign Profiles...? What are the Output settings for your Export preset?
You would expect an appearance change when you change profile assignments without changing the color's CMYK values—a coated profile like the default US SWOP has a considerably larger color gamut than newsprint.
So a dark saturated purple or blue is going to change in appearance when it prints on the highly absorbent newsprint. The assigned CMYK profile attempts to show you that difference in the preview. So here two Photoshop docs filled with the same 85|100|0|0 CMYK values but with different assignments (showing in the lower left info box):
the blue-shifted PDF prints perfectly fine on our office printer
I wouldn't bet on your office printer being capable of accurately proofing the color as it will print on newsprint.
Also, what you are describing would happen if your document had the default US SWOP Coated profile assigned and you exported with the Output tab like this:
In this case, if your purple was an InDesign CMYK color or swatch, it would export with its values unchanged because the Convert to Destination (Preserve Numbers) setting, protects native CMYK color values. However, it would be previewed via the US Newsprint (SNAP) profile and the appearance would change when viewed in Acrobat.
That is the situation. The purple is a CMYK swatch and I'm converting to SNAP 2007 with the preserve numbers setting. I can see that's had the appropriate effect on the photo (it becomes a little less vibrant, as expected, as the ink values are adjusted accordingly for newsprint) - I just didn't expect a difference in the CMYK object because of this "preserve numbers" feature. So from what you're saying, indesign and acrobat are approximating visually how newsprint will affect my CMYK purple.
To be honest, I didn't take the doc profile into account. I'm sure it's US SWOP V2. Does the document profile beed to match the PDF output intent?
Thanks for looking into this btw. Much appreciated.
The purple is a CMYK swatch and I'm converting to SNAP 2007 with the preserve numbers setting
The Preserve Numbers choice is preventing the conversion of InDesign colors and allowing the conversion of placed objects with conflicting profiles. So yes Acrobat is showing you how the color with unchanged output numbers will change in appearance when it prints on newsprint. You have to keep in mind that the SNAP softproof is only accurate if the press profile really is SNAP—newsprint can be very difficult to predict, but color definitely changes relative to a coated sheetfed press.
Does the document profile need to match the PDF output intent?
If you leave the assigned profile as US SWOP your InDesign color is going to preview as it would print on a coated sheet and not Newsprint. If you reassign SNAP you should see the bluer purple, so you can either manually add more magenta, or use Edit>Convert to Profile... rather than Edit>Assign profiles... which will convert the purple value—your swatch would have more magenta.
Makes sense. Thanks for explaining all this.
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