This is part of a series about my experiences in publishing a book. The series starts here.
I previously reported on gang hard proofing. Yesterday, Jerry asked me for the final copies of each of the images for the book. I had previously identified seven images for which the standard Adobe gamut mapping with relative colorimetric intent were not acceptable. I turned on Lightroom’s soft proofing feature and set the output medium to Coated GRACoL 2006 (ISO 12647-2:2004). I created virtual copies of the seven images. I made corrections with the adjustment brush, and exported the images to .psd files in ProPhoto RGB.
I opened the files in Photoshop, converted them to Coated GRACoL 2006 (ISO 12647-2:2004), saved them as TIFFs, and proofed them on my Epson 4900 on Exhibition Fiber paper. I had previously determined that the entire Coated GRACoL 2006 (ISO 12647-2:2004) gamut lies within the 4900/Exhibition Fiber gamut. I made sure that the Black Point Compensation box in the Ps print dialog was unchecked.
The prints looked good. Too good, in fact. I got suspicious. I measured some dark areas on the prints with a reflection densitometer, and got readings in the 1.8s. That seemed too high for offset lithography. I got a recent issue of LensWork, and measured the darkest spots I could find in the 4-color images: 1.66. Then I measured the darkest spots I could find in the duotone images: 1.76.
I created a PPRGB image in Ps, and filled it with 0/0/0. Then I converted it to Coated GRACoL 2006 (ISO 12647-2:2004), and printed it with the Black Point Compensation checked and unchecked. With the box checked, I got readings of 2.10 with the densitometer. With the box not checked, I got 1.88.
So, it seems that the collective wisdom of the profile and the Adobe color management software is that the printer can print as dark as a density of 1.88. If that’s true, that’s wonderful.
As a side issue, things would be a lot easier if Lightroom supported CMYK files. I’m not sure why they don’t. The program knows enough about CMYK files in general, and Coated GRACoL 2006 (ISO 12647-2:2004) in particular, to make soft proofing work. That means it can get from its internal color space to CMYK. Why can’t it get from CMYK to its internal color space?
I looked at the GRACoL 2006 gamut in Gamutvision:
The black point has an L* of 11.
I ran this little code snippet in Matlab:
Photoshop/Adobe was right all along. Now to find out what I can really expect off the press.