Johnson's Criteria

The number of raster lines of a display required to interpret different levels of objects within a displayed scene. These levels are:

1. No detection

2. Detection

3. Shape orientation

4. Shape recognition

5. Detail recognition

Sometimes used in training simulators to determine required resolution of visual displays.

JPEG

Joint photographic experts group. Defined an image-compression algorithm based on a linear transform called the discrete consine transform (DCT). The image is first block coded, each block transfomred using the DCT, the transform coefficient guantized, and then subjected to a lossless compression algorithm. Loses some information about high spacial frequencies and suffers from some block artifacts. (See also Discrete Cosine Transform and Block Coding).

Junctions

X-,T-,L-, I- Junctions

Line junctions in an image are powerful cues to depth relations. e.g. T-junctions are cues for occlusion, X-junctions can be cues for Transparency.