I'm creating a PDF file for printing a color book. Typically, I use PDF/X-1A:2001, which is recommended by the printer and which always gives me good color. This time, however, certain bright blues are coming out very gray. All the other colors look good. Does anyone have any suggestions for fixing the problem? I know almost nothing about color conversion as does the designer I'm working with. Thanks for any and all help.
certain bright blues are coming out very gray. All the other colors look good
Were these colors defined as CMYK, or are they RGB or Spot colors. Bright blue could be out of gamut for the CMYK space you are using.
PDF/X-1a forces all color into the destination CMYK space—usually your document's CMYK profile. The blues in the scan are out-of-gamut. Blues can be problematic for both converting and soft proofing because a good part of the blue spectrum is out of the CMYK gamut and cyan is out of the RGB gamut.
Obviously there are plenty of books printed where color has to be exact.
Depends on how far out-of-gamut the color is RGB 0|0|255 can't be printed under any circumstances.
If you know what you're doing it can help to color-correct and make the conversion in Photoshop, but you can't avoid the gamut. Selective Color can be used to manipulate Blue and Cyan after the conversion—you can look at the output numbers in the Info panel and make sure cyan is near 100% with a minimum of yellow and black.
If the blues lean to cyan they will likely print brighter because cyan can't be displayed accurately.
I'm looking at the swatch book, not the screen renderings, to judge the spots.
I haven't calibrated the monitor in a few weeks, so it may be off, and you screen cap looks a tad more magenta, I think than my color in photoshop, but that could be the forum. Here's a grab from my screen:
And as you pointed out, pretty much anything other than a custom mixed spot is going to be some sort of compromise.
I appreciate all your help. As I said, I'm a total novice at this, so you guys have lost me on the spot channel. In any case, this book is going to Lightning Source, so it's a one-size-fits-all print job, with no tweaking. What I send them is what I get. In any case, it's not a solid color, I only sampled one pixel to give you an idea of the range. Here's the image: