Glossary

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Action

A Photoshop operation that automates a single operation or a sequence of operations. Photoshop comes with default Actions, and you can create and save custom Actions to a file. When you need a particular Action or Action sequence, you can play it and apply its operations to any image by pressing a function key.

Actions palette

The Photoshop palette that contains controls for recording and playing back Actions.

additive primary colors

Red, green, and blue, which are used to create all other colors when direct, or transmitted, light is used (for example, on a computer monitor). When pure red, green, and blue are superimposed on one another, they create white.

Adjustment layer

In Photoshop, a separate layer containing the mathematical data for an adjustment operation applied to an image. You can re-edit the Adjustment layer at any time during the imaging process.

Adobe Gamma calibration package

A package that includes Adobe Gamma software, the Gamma Wizard, and ICC (International Color Consortium) color profiles for some RGB devices. You can use the Gamma software to calibrate your monitor on the Windows operating system.

alpha channel

An 8-bit, grayscale representation of an image. Alpha channels are selections that have been stored for later use. The values of gray can represent tonality , color, opacity, or semitransparency. Image formats that support alpha channels include Photoshop (PSD), Photoshop 2.0, Large Document Format (PSB), BMP, JPEG 2000, Photoshop PDF, PICT, PICT Resource, PIXAR, Photoshop Raw, Targa (TGA), and TIFF.

analog

Signals made up of continuously varying wave forms.

anti-alias

A process that adds a 2- or 3-pixel border around an edge that blends into the adjacent color to create a small transition zone. Without the anti-alias, an image would look stair-stepped and not have smooth transitions between colors. The width of an anti-alias is determined by the resolution of the image; you have no control over its size .

artifact

An unintentional image element produced in error by an imaging device or inaccurate software. Dirty optics are one common reason for artifacts.

aspect ratio

The height-to-width ratio of a selection, an image, or ”in the case of digital video ”a frame.