Version 1.0, August 31, 2001, Copyright, Hugh Jack 1993-2001

14.3 LIGHTING AND SCENE

 

· There are certain features that are considered important in images,

  1. - boundary edges
  2. - surface texture/pattern
  3. - colors
  4. - etc

 

· Boundary edges are used when trying to determine object identity/location/orientation. This requires a high contrast between object and background so that the edges are obvious.

 

· Surface texture/pattern can be used to verify various features, for example - are numbered buttons in a telephone keypad in the correct positions? Some visually significant features must be present.

 

· Lighting,

  1. - multiple light sources can reduce shadows (structured lighting).
  2. - back lighting with luminescent screens can provide good contrast.
  3. - lighting positions can reduce specular reflections (light diffusers help).
  4. - artificial light sources provide repeatability required by vision systems that is not possible without natural light sources.