Software program that allows the operator to manipulate black and white and color images, changing such things as color, tone, contrast, size, scale and content.

Color images on the computer are created by combining different color channels. In RGB, the most commonly used color model, the channels are red, green and blue.

First suggested by French photographer Hippolyte Bayard, the technique of combining separate photographic negatives to create a single image.

The basis of almost all commercial four-color printing, in which gradations of tone and color are achieved by a system of minuet dots, applied by the printing press.

Used in both manual retouching and in Photoshop to isolate a portion of an image so that changes affect only the selected area and not the rest of the image.

Short for “picture element". The smallest individual component of a digital image, usually a colored dot. The greater the number of pixels per inch, the greater the resolution.

The process of altering an image, especially to remove defects or change its content. Retouching includes correction of mechanical problems, such as removing shadows or dust, as well as alterations to the image. Retouching may be performed with pencils, a brush and inks, or with an airbrush on a negative, before printing, or on a print. Digital retouching, which makes changes to pixel values to enhance or change the appearance of the image, is typically done on a computer before printing.

The amount of contrast in the image ranging from black to white.