Technique 14: Getting Files Ready for Offset Printing
Selecting prepress settings
Soft proofing your project
Checking for out-of-gamut colors
Adding spot color channels
Photoshop includes many high-end features that let users create professional-quality separations for high-quality offset printing. Typically, you create your Photoshop projects in RGB (red, green, blue) color mode; this is based on the colored light projected by your monitor. Commercial printing presses use a different color mode, CMYK (cyan, magenta, yellow, black), based on the inks used by the presses. Converting RGB images to CMYK mode and getting the printed results to match your monitor can be a time-consuming and sometimes frustrating process.
Using the tools included with Photoshop, you can cut down on the frustration by selecting CMYK prepress settings provided by your commercial printer, and soft proofing your project files — previewing a fairly accurate approximation of the printed image on-screen. In addition, you can check the colors in your image to make sure they are all printable. Out-of-gamut (non-printable) colors can then be corrected before your project goes out the door.
This technique walks you through the world of offset printing and preparing files for high-end output. You find out how to select color settings based on printing press settings, convert the image to CMYK mode, soft proof your project, and add printer’s marks. From there, you find out what spot colors are and how you can use them to give your projects real visual punch.
Although some folks might find this all a bit daunting, don’t worry! I explain everything as simply as possible, and if you follow the step-by-step directions, you shouldn’t have trouble — even if you’ve never worked with a commercial printer before.