Photo Glossary

Gamma

A measure of the brightness and contrast of a monitor or the midtone brightness of digital image.

Gamut

The range of colors that can be captured or displayed by a device.

GIF

Short for graphic image format. A universal type of image file for use on the Web. A Gif contains only 256 colours so it's best used for solid colour graphics such as logos and buttons, rather than high quality photographic images.

Gigabyte (Gb)

A unit of computer memory equivalent to 1024 megabytes.

Glossy paper

Printing paper with a smooth shiny surface finish.

Gradation

The tonal contrast range of an image.

Grade

The contrast rating of black and white printing enlargement papers. Zero is the lowest contrast and 5 is the maximum contrast.

Gradient

A gradient is a color fill that gradually blends from one color to another. A gradient can contain more than two colors, all fading smoothly from one to another.

Graduated fill

See gradient

Graduated filter (or Gradated filter)

Used to balance the light of a scene with overly bright highlights. A graduated neutral density filter is clear from one edge to approximately the middle of the filter, then gradually increase in density towards the opposite edge.

Grain

Exposed and processed silver halides on the film emulsion that turn black and form miniature "grain" that make up the image on a piece of film.

Gray card

Card with an 18 percent gray tint (reflectance) used to determine exposure by taking a meter reading from subject light reflected by the card.

Gray scale

Set of tones displayed in steps from minimum to maximum density. The 256 gray levels system divides the gray scale into 256 sections with black at 0 and white at 255.

Ground glass

Frosted glass used as a viewing mechanism in cameras without prisms. The glass is placed so that the lens projects the image against the glass for focusing and composition purposes.

Guide number

Indicates the output capacity of an electronic flash.