Process Color Book "U.S. Letter - Perfect Bound"Having discovered www. lulu. com I wondered how I could obtain accurate printing results. I then decided to create a Color Reference Book for the format I was interested in. This I would then order, and use the color values which matched the color I would like to have. And so the "Process Color Book U. S. Letter Perfect Bound" was born! I have used increments of 0, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 95, 100 percent, a total of 26. 364 CMYK colors.