Photoshop CS5: The Missing Manual

Printing on a Digital Press

In the past, when you prepared a document for a commercial printer, you would—and in many case still do—convert your images to the CMYK color mode (see the previous section on commercial offset printing) before you inserted them in a page-layout document and certainly before you fired them off to the printing company. However, that process is changing because an increasing number of printers also use digital presses.

Digital presses work just like laser printers or copiers; they use electrostatic charges to transfer images from cylinders to the print surface. Like commercial offset presses, digital presses are primarily CMYK printers, but they use toners instead of inks (which is why they can't print spot-color inks). Some digital presses, like the Kodak NexPress, offer additional toner spot-color printing but they're limited to very specific colors like red, green, or blue. Rather than being used for special objects like logos, these additional spot colors typically expand the gamut of the CMYK toners, much like light cyan and light magenta in inkjet printers. The following sections explain how to prepare various types of images for a run on a digital press.

Printing RGB Images on a Digital Press

Digital presses handle images much like expanded-gamut inkjet printers (see Printing on an Inkjet Printer). Because the RGB to CMYK-Plus conversion occurs at the printing press's processing RIP (see the box below) by using a built-in profile specific to that press ...