AVG4(1)AVG4(1)NAMEavg4 - Downfilter an image by simple averaging.
SYNOPSISavg4 [ -o outfile ] [ infile ]
Avg4 downfilters an RLE image into a resulting image of 1/4th the size,
by simply averaging four pixel values in the input image to produce a
single pixel in the output. If the original image does not contain an
alpha channel, avg4 creates one by counting the number of non-zero pix‐
els in each group of four input pixels and using the count to produce a
coverage value. While the alpha channel produced this way is crude
(only four levels of coverage) it is enough to make a noticeable
improvement in the edges of composited images.
infile The input will be read from this file, otherwise, input will be
taken from stdin.
If specified, output will be written to this file, otherwise it
will go to stdout.
SEE ALSOfant(1), rlecomp(1), smush(1), urt(1), RLE(5).
Rod Bogart, John W. Peterson
Very simple minded - more elaborate filters could be implemented.
4th Berkeley Distribution Nov 12, 1986 AVG4(1)