GLOSSARY

BRIGHTNESS

The lightness or darkness of the image.

CHANNEL

The component of an image. Your scanned image has three channels:

 

red, green, and blue (RGB).

CONTRAST

The gradation of shades in an image. A high contrast image has very

 

dark areas and bright areas without many middle shades. A low contrast

 

image has many tones that are close to the same brightness. Low

 

contrast images are often described as looking ‘flat’.

CROP

To trim and delete the unwanted edges of the image.

DPI

Dots (pixels) per inch.

EMULSION SIDE

The side of the film coated with the photographic material.

GAMMA

The contrast of only the middle tones.

HIGHLIGHTS

The lighter areas of the image.

HISTOGRAM

A graph showing the amount of each level of the 256 brightness levels.

IEEE 1394

Refer to the page 106.

INTERPOLATION

A methord of adding new pixels to an image when resampling up.

JPEG

The JPEG (Joint Photographic Experts Group) compression standard is

 

capable of producing a high compression ratio while maintaining image

 

quality. JPEG is a widely supported image file format.

MIDTONE

The middle shades of an image, in between light and dark.

NEUTRAL

Having no colour cast, such as black, white, or grey.

PICT

(Macintosh operating system only) The PICT graphic file format uses a

 

lossless compression scheme and is compatible with many Macintosh

 

applications.

PIXEL

Abbreviation for picture element. The dots that make up an electronic

 

image.

RESAMPLE

To change the number of pixels in the image. If pixels are discarded

 

when shrinking an image, it is called resampling down. If new pixels are

 

created in an image, it is called resampling up (see page 89).

RESOLUTION

The number of pixels in a given area of the image; such as pixels per

 

inch or pixels per centimetre. High resolution is the term for an image

 

with a lot of pixels in a given area. Low resolution means there are not

 

many pixels in a given area.

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