Our experience affects how we perceive images. For example, we associate objects that are physically higher with higher data values. So if one object is in front of another, as determined by depth cues, then we think it must have a greater data value. One depth clue is occlusion, so in the image below where the black square occludes the white square, we consider the black square to have a higher value.
Large areas may be associated with the background and thought to have lower values. Here is an example where the high data values, given by bright blue, may be perceived as being in the background, and thus having lower data values.
Another problem is the introduction of apparent discontinuities in continuous data by the use of pseudocolor. Here is an example of using the rainbow color scale for data display creates distinct regions that are false. Note that this is the same data as the previous image.
Brightness contrast affects the perception of hue. In the image below, the gray circle on the left appears to be darker than the (identical) circle on the right.
Last modified on February 11, 1999, G.
Scott Owen, firstname.lastname@example.org
Main Perception Issues Page
HyperVis Table of Contents