Jim wrote:
I'm interested in the algorithm that would create a bmp, or gif file
from a matrix of numbers say 400x400. Also in code that would take
arbitrary scaled data and translate those numbers into gray-scale or
color representations.
Anyone know about this?

Shameless plug. I do an Imager addin for XL that does exactly this for
greyscale and various commonly used false colour mapping with optional
linear and log scaling. It is useful for modest amounts of bulk data.

http://www.nezumi.demon.co.uk/consult/excel/image.htm

Hope this helps.

Regards,
Martin Brown