A Brief Note on Color

Print 

Introduction

Our digital printers use the standard four color print process that most every printing press uses – CMYK, which stands for cyan, magenta, yellow, and black. These four colors are combined to give you the full-color reproduction you expect with printed materials. Monitors and digital images use a different color space called RGB, which stands for red, green, and blue. If you are unfamiliar with color management and are already glazing over, feel free to skip ahead. Blurb’s PDF to Book workflow follows industry standards for digital offset printing and color management. Most customers will receive quality printed results without needing to understand the details around color spaces and color management.

In the PDF to Book workflow, all RGB color spaces are assumed to be sRGB, then converted to CMYK at the HP Indigo print device. Therefore, all CMYK color spaces remain as is and are not converted. Depending on your preferred color space, you’ll want to follow these guidelines for optimal print results:

1. If your images are already sRGB, it is not necessary to convert to CMYK because the HP Indigo is preset to convert sRGB to CMYK.
2. If your images are Adobe RGB, ProPhoto RGB, Colormatch RGB, or another RGB color space, the optimal workflow is to convert your images to the CMYK profile optimized for the HP Indigo presses that Blurb uses. The Blurb ICC Profile can be downloaded from the Blurb Color Management Resource Center.
   
   Color conversion is best done via an imaging program, such as Adobe® Photoshop®,prior to placing your images or graphics into Adobe® InDesign® or your preferred layout tool.
   
   If you have already converted your images to sRGB for use in Blurb BookSmart® you can either keep them sRGB or convert to the Blurb ICC Profile.
3. If your images are already CMYK, you also should not convert back to RGB or a different CMYK space. If you choose to do so, there is only a small gain in color vibrancy and much more degradation of the file for the amount of effort needed.
   
   Use a CMYK color palette for native graphics and text within InDesign® or your layout tool of choice. The digital presses we use are unable to consistently process spot color at this time.

For optimal results in color reproduction and overall quality, we recommend downloading and installing the Blurb ICC Profile, and then setting up Adobe Photoshop® and InDesign® according to the instructions found under the PDF to Book tab in the Color Management Resource Center.

Continue to Next Section: Previewing Your Exported PDF/X-3 Files