The total number of bits used to represent a single pixel. In a truecolor or grayscale image, with or without an alpha channel, the pixel depth is therefore equal to the product of the sample depth and the number of channels. For example, an RGBA image (four channels) with 16 bits per sample would have a pixel depth of 64 bits. In the case of channels with unequal sample depths, simply add the number of bits for each channel; e.g., on a typical PC ``high-color'' display, the number of bits for red, green, and blue channels is usually five, six, and five bits, respectively, resulting in 16-bit pixels. PNG channels in a given image always have equal sample depths.
The number of bits stored for each pixel in a bit-mapped image. The greater the pixel depth (the more bits per pixel), the wider the range of intensity levels or colors a bitmap can represent. The number of possible pixel values is 2 to the N, where N is the pixel depth. (7/96)
The smallest unit of data in a digital image. Together, the small discrete elements constitute an image that can be seen on a monitor or printed on a substrate. A pixel's code contains information relating to colour and placement within the larger image. The number of bits of tonal range capability assigned to the pixels in an image. For example RGB 24 bit colour means a pixel depth of 24 bits, 8 bits or 256 levels per colour.
The amount of data used to describe each coloured dot on the computer screen. i.e. Monochrome is 1 bit deep. Greyscale is 8 bits deep. RGB is 24 bits deep. Images to be printed as CMYK separation should be 32 bits deep.