Learn from basic perception principles

The tutorial on Perception and Cognition for Visualization, Visual Data Analysis and Computer Graphics was a little shallow considering the audience. The whole morning session could have been concatenated into a half hour session without loosing any content. I still got a couple of useful insights from it to improve visualization.

A good visualization is one for which equal steps in data values produces equal perceptual steps. The next graph shows that not all visual dimensions are equal in that respect. Ideal slope is 1.

It is interesting to view the human visual system as a band-pass filter. The system is most sensitive in the a mid-range spacial frequency, but most importantly, we see from the graph that luminance is much more efficient for representing high-frequency visual details.

It is thus a good idea to use intensity to display high-frequency details in an image. On the other hand, color coding should be used for very low frequency information.

Color attracts pre-attention. It can be used by the visual system to perform an effortless search (see picture below). But color should be used with moderation. Large patches of bright color have very little effect.

The perception of a scene is highly influenced by the nature of the task performed by the viewer. The intention drives visual behavior.

Images in this post are all from the presenter's slides available here.