I’m using Adobe Creative Suite Premium 5.5 on Mac OS version 10.6.8.

I just prepared a job in Adobe InDesign for press.

The job is a 12-page newsletter with 2 pages 4 color and 10 pages grayscale.

My Creative Suite color space is synchronized in Adobe Bridge to “European Prepress 3”.

Most of the photos, which originated from various digital cameras, were retouched in Photoshop and linked to InDesign.

There were several graphics, some created in Illustrator and some in Photoshop which were created by importing graphic image and tracing them and coloring them in Illustrator and Photoshop in CMYK.

Two of the graphics are positioned side-by-side on a page. Each graphic consists of a dark blue with a light blue pattern. A sample of the colors was imported from Illustrator to Photoshop via clipboard and then sampled to match the two colors.

I then generated several PDFs and the colors of these two graphics matched.  I regenerated one of the graphics, taking great care to match the colors.

When I exported the InDesign file as a PDF and viewed it on another computer, the colors of each of the two graphics didn’t match. When viewed on my computer, they did appear the same. When hen I sampled the colors of each graphic in its native Illustrator or Photoshop document, the color values were the same.

A separate, but not unrelated issue:

Then for the print version of the document, I had to do a conversion of the graphics to grayscale. The grayscale values of the native Photoshop file and the native Illustrator file did not match.

I copied a sample of the light gray from the Illustrator file into the Photoshop file.

Its values in the Illustrator file were:

R180, G180, B180 or C0, M0, Y0, K29 (#B4B4B4).

When I sampled the gray in the Photoshop file, the values were:

R198, G198, B198 or C24, M18, &19, K1 (##C6C6C6).

I manually adjusted the values of the grayscale in the Photoshop file so that the two graphics would match. This worked.

Could someone please explain to me why these colors changed?