Is an average gradient of a characteristic curve, describing similar characteristics to gamma, but measuring the slope from a line joining the lower and upper of the curve actually used in practice.

A compression technique used in Fax Group 4. It produces very good results for black and white, and is frequently used as an option in TIFF files for black and white images. It is also used in Adobe Acrobat (PDF) files.

A method of adjusting a CCD sensor's sensitivity to light.

"Gain and level are image processing terms which roughly correspond to the brightness and contrast control on a television. The gain is the " contrast " and the level is the "brightness". By changing the level the entire range of pixel values are linearly shifted brighter or darker. Gain on the other hand linearly stretches, shrinks the intensity range, thus altering the contrast."

The contrast affecting the mid-level grays or midtones of a image. Adjusting the gamma of an image allows you to change brightness values of the middle range of gray tones without dramatically altering the shadows and highlights.

The measure of contrast that results in lightening or darkening the midtone regions of an image. Also, the amount of midtones need to be adjusted on a monitor.

The range of colours and tones a device or colour space is capable of recording or reproducing. The human eye can sense many more colours than can be reproduced on a computer monitor in RGB colour space.

The editing of an image to reduce the colour gamut so that the image can be displayed or output within the limits of a particular device.

The plotting of an image colour gamut into the CIE colour space.

Putting a group of images or jobs on the scanner or press at one time.

An image softening effect utilizing a bell shaped gaussian distribution to apply the softening effect.

GCR (Grey Component Replacement) A technique for reducing the amount of cyan, magenta, and yellow ink in an area and replacing them with black ink.

"In time exposure photography, an object that is only partially recorded on the film and therefore has a translucent, ghost-like appearance. Some people also refer to " flare " as a ghost image."

Graphic Image File format. A widely supported image-storage format promoted by ComputerServe that gained early widespread use on on-line services and the internet.

"The most recent GIF standard that allows the selection of area for transparency. The primary use is on the Internet and other on-line services. Like GIF it is 256 colour or 8 bit imaging. A transparent GIF (Graphics Interchange Format) is an image file that has one colour assigned to be "transparent" so that the assigned colour will be replaced by the browser's background colour, whatever it may be. As an example, if you have created a rectangular GIF image of a large blue square on a white background but are only interested in having the blue square appear on your Web page, and don't want to see the white background, you can make the white background colour transparent so that it changes to whatever the Web page's background colour is (yellow, for example). Then, when you view the Web page, you will only see a blue square on the yellow background."

A measure of computer memory or disk space consisting of about one thousand million Bytes ( a thousand megabytes). The actual values is 1,073,741,824 bytes (1024 megabytes).

Describes a printing paper with a great deal of surface sheen. Opposite: matte.

A smooth transition between black and white, one colour and another, or colour and no-colour.

A smooth spread between colours.

A photo made up of varying tones of black and white. Grayscale is synonymous with black and white.

An image type made up of black, white, and grey pixels. Also, the range of greys in such an image measured in either percent black (0% is white and 100% is black) or grey levels (0 is black and 255 is white).