Anyone know how to convert a truecolor (24bit) image to 16 colors?

Photoshop -> image mode -> indexed color -> 16 colours or…

ImageMagick can do it in PHP!

http://www.imagemagick.org/script/convert.php

Seems useful, but the only thing i could find with that was the prefered colors, not any limit…

http://www.imagemagick.org/script/command-line-options.php#colors

Thats the point, i have an image, jpeg, that has a background, then a bunch of pins on it (inverted triangles), those
pins could be either hollow (just an outline), red, cyan, or white, the pins are also shaded, because its a jpeg, its got bad artifa
cts/etc.

ive found mucking about in PSP that if i convert it to 16 colors, the pins become a complete solid color mostly, so it'd be
much easier to determine the pin color if its been converted to 16 colors first