Whether you are printing an image to your desktop printer or sending it to a prepress facility, knowing a few basics about printing makes the print job go more smoothly and helps ensure that the finished image appears as intended.

Types of printing

For many Photoshop users, printing a file means sending the image to an inkjet printer. Photoshop can send your image to a variety of devices to be printed directly onto paper or converted to a positive or negative image on film. In the latter case, you can use the film to create a master plate for printing by a mechanical press.

Types of images

The simplest images, such as line art, use only one color in one level of gray. A more complex image, such as a photograph, has varying color tones. This type of image is known as a continuous-tone image.

Halftoning

To create the illusion of continuous tones in images, printers break down images into dots. For photos printed on a printing press, 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.

Note: Although inkjet printers also use dots to create the illusion of continuous tones, their dots are of uniform size and much smaller than the dots used by most printing presses.

Color separation

Artwork intended for commercial reproduction and containing more than one color must be printed on separate master plates, one for each color. This process, called color separation, generally calls for the use of cyan, yellow, magenta, and black (CMYK) inks. In Photoshop, you can adjust how the various plates are generated.

Quality of detail

The detail in a printed image depends on its resolution and screen frequency. The higher the resolution of an output device, the finer (higher) a screen ruling (lines per inch) you can use. Many inkjet printer drivers offer simplified print settings for higher quality printing.

For a video on printing photos, see www.adobe.com/go/vid0015.