DESIGN STATEMENT:
This procedure generates a series of 1275 images, each of which has one of five different black-and-white background patterns and two pairs of concentric circles in complementary colors.  For very low and very high values of the series, the concentric circles will be drawn in red and its complement, cyan, and one set of circles will appear to be solid, while the other will appear to be a single, unfilled circle.  For values of the series that are not so extreme, the sets of concentric circles will be more obviously concentric, and the colors will be closer to a dull purple and its complement, a shade of sea-green.

TECHNIQUE STATEMENT:
This procedure generates an image drawing from five different source images as a base.  The source image is selected with a modulo procedure: for values of n that are exact multiples of 5, source1 is used; for values of n where (modulo n 5)=1, source2 is used, etc...
Any set of five different source images could be inserted into the (let* ((... portion of the procedure, but since computing spots takes time, we'd recommend using source images that are no larger than 20x20.  The source images we've already inserted into the procedure are simple black and white patterns that we found online and edited and scaled with GIMP tools.
	The source image is then converted to a list of spots using the image.get-spot procedure and iterating it over the list of all of the positions in the source image (this list is generated with a call to the list-of-positions procedure).
	The spots are then scaled and rendered on the new image (i.e. parameter “canvas” in the procedure) with a call to spot.xy-draw.  The spot.xy-draw procedure was inspired by Sam's “spot.decadraw” procedure, but was modified so that it didn't preserve the scale of the source image, but rather scaled with different factors for the width and height.  In order to scale the width and height of the source image to fit the width and height of the new image, we divided the new image width and height by the source image width and height in the (let* ((... portion of our main procedure to generate “image1-x-scale” and “image1-y-scale”.  We then did the same to scale the remaining source images.
	We also wanted to draw concentric circles in complementary colors in the corners of the new images.  We designed the procedure so that the base color, “color,” and its complement would vary from (0 0 255) to (255 0 0) across the series.  Note that our series works for values of n ranging from 0 to 1274, since 255*5=1275.  We also designed the procedure so that the concentric circles would have “opposite” ratios; for example, if the ratio of the upper left-hand set of circles is .25, then the ratio of the lower right-hand set of circles is .75.  The ratio itself is dependent on n, and will vary from being very close to 0 to being very close to 1—but will never equal 0 or 1, since these values generate an error in the call to image.draw-concentric-circles!.  The smallest possible ratio in the series is 1/1276, and the largest possible ratio is 1275/1276.