Dithering: to reduce color images to black and white by replacing colors with dots, dashes, and x's that, at a distance give approximately the same impression as the original image.
Filters: alter an image or selection to achieve a particular effect. Filters alter each pixel's color based on its current color and the colors of any neighboring pixels.
Grayscale: Depending on the display there may be between 4 and 64 different shades of gray that may be substituted for the colors in an image.
Orientation: If an image is taller than it is wide, the orientation is referred to as portrait. Otherwise the orientation is called landscape.
File Formats: There are almost as many ways to store a graphic image on disk as there are producers of these images. Here are a few of the more common file name extensions for such graphics files.
ART: PFS, First Publisher
BMP: Windows
EPS: Adobe PostScript
GEM/IMG: Ventura Publisher
GIF: CompuServe Graphic Image File
HGL: HP Graphics Language
JPG: Joint Photographers Graphics
MAC: MacPaint
PCX: PC Paintbrush
PIC: Lotus Graphic File
RLE: Older Windows
TGA: Truevision Targa
TIF: Many scanners
WPG: WordPerfect Graphic
WMF: Windows Meta File