Information Technology Reference
In-Depth Information
Figure 5.6:
In (a) a detailed object moves past a fixed eye, causing temporal frequencies beyond the response of
the eye. This is the cause of motion blur. In (b) the eye tracks the motion and the temporal frequency becomes
zero. Motion blur cannot then occur.
5.2 Dynamic resolution
As the eye uses involuntary tracking at all times, the criterion for measuring the definition of moving-image portrayal
systems has to be
dynamic resolution
, defined as the apparent resolution perceived by the viewer in an object
moving within the limits of accurate eye tracking. The traditional metric of static resolution in film and television has
to be abandoned as unrepresentative of the subjective results.
Figure 5.7(a) shows that when the moving eye tracks an object on the screen, the viewer is watching with respect
to the optic flow axis, not the time axis, and these are not parallel when there is motion. The optic flow axis is
defined as an imaginary axis in the spatio-temporal volume which joins the same points on objects in successive
frames. Clearly when many objects move independently there will be one optic flow axis for each.
