In effect draws a pencil outline on top of a picture. You can choose how much colour to preserve from the original, and how heavy a "pencil" to use.
The critical routine is written in x86 Assembly Language. It's too slow in pure BASIC. However, I've left a "dummy" procedure at the end of the Text listing, so that people can see how the Edge Detector routine works.
In fact, it ooks for a certain (adjustable) minimum rate-of-change in either of the R, G or B values either side of a given pixel. It looks at all 8 pixels and looks for the minimum rate of change in each of the 4 directions through the central pixel.
BMP Edge Detector is a simple tool designed to detect the edge of any BMP image file.
