Regular, Random, and Jittered Sampling Using Box Filter and Triangle Filters

Note: Slow. . . but worth it!
Sampling: The following (small) applet illustrates different types of sampling using different types of filters. The sampling and filters are (clockwise, starting with top left corner): Regular samping with a box filter, random sampling with a box filter, jittered sampling with a box filter, and jittered sampling with a triangle filter. With each iteration more points are computed in the box area.

The function that assigns a color value to the pixel is given by:
color = sin(x2 + y2)

Regular sampling divides the image portion into equal squares, and computes the value of the above function for the center of each square.
Random sampling selects a number of points at random in the image portion and computes the value of the function for those random points.
Jittered sampling divides the impage portion into equal squares again, but this time selects not the middle point but a point at random.
Box filter assigns the same value of color to all points in the portion of the image being computed.
Triangle filter gives more weight to those points nearest the point with the color being computed.

Or something like that. . . .

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Jessica Shepherd (jshepher@cs.utah.edu)
September 24, 1997