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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 and most commonly uses cyan, yellow, magenta, and black (CMYK) inks. 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.