Digital Photo 2: Vocabulary List 4
Define the following terms. Summarize the definitions in your own words.
1. Channel: an image component that contains the pixel information for an
individual color (grey = 1 channel, RGB = 3, CMYK = 4)
2. Alpha Channel: a special 8-bit greyscale channel where masks or selections are
stored
3. Posterize: special effect that reduces the number of shades of grey or colors to a
specified #, usually a low #.
4. Rasterize: to convert a vector-based or object-oriented image into a bitmapped
image (into pixels)
5. Scratch Disk: hard drive storage space that is temporarily used as workspace to
process operations and store parts of an image and a back-up version (it’s like
extra RAM and used when there isn’t enough actual RAM)
6. Saturation: the purity of a color, independent of its hue and brightness; the more
grey a color contains , the lower its saturation
7. Bit Depth: a bit is the basic element of digital data; a bit is either on or off, 1 or 0.
bit depth is how many bits each pixel contains; each pixel has a “depth of 1 to 32
bits (more bit depth = more possible colors) For example, a bit depth of 1 means
each pixel is either black or white (1 or 0); a bit depth of 2 means there are 4
possible variations (00, 01, 10, or 11); a bit depth of 8 means there are 256 colors
or grey values