Adobe 23101335 User Guide - Page 385

375 Chapter 14: Printing (Photoshop) P rinting is the process of sending your image to an output device. You can print on paper or film (positive or negative), to a printing plate, or directly to a digital printing press. About printing Whether you are providing an image to an outside service bureau or just sending a quick proof to a desktop printer, knowing a few basics about printing will make the print job go more smoothly and help ensure that the finished image appears as intended. Types of printing When you print a file, the Adobe Photoshop application sends your image to a printing device, either to be printed directly onto paper or to be converted to a positive or negative image on film. In the latter case, the film can be used to create a master plate for printing by a mechanical press. Types of images The simplest types of images, such as line art, use only one color in one level of gray. A more complex image, such as a photograph, has color tones that vary within the image. This type of image is known as a continuous-tone image. Halftoning To create the illusion of continuous tones when printed, images are broken down into a series of dots. This process is called halftoning. Varying the sizes of the dots in a halftone screen creates the optical illusion of variations of gray or continuous color in the image. Color separation Artwork that will be commercially reproduced and that contains more than a single color must be printed on separate master plates, one for each color. This process is called color separation. In Photoshop, you can adjust how the various plates are generated and create traps. Quality of detail The detail in a printed image results from a combination of resolution and screen frequency. The higher an output device's resolution, the finer (higher) a screen ruling you can use. A valuable resource for all aspects of print publishing, from early planning through prepress, is the Print Publishing Guide, an Adobe Press book. For information on purchasing Adobe Press books, visit the Adobe Web site at www.adobe.com or contact your local book distributor.