These examples and libraries will hide a binary image in the low order bit of a full color image. The binary image is invisible until you remove the other colors.

The image on the left has the image on the right hidden in it.

stegLibrary.tcl A library of procedures:
Reduces the number of colors in an RGB image from 24 bits to 21 bits.
Inserts a binary diagram into the low order blue bits of a full color image
Extracts the low order blue bit and creates a black & white image.
stegSave.tcl Demonstrates creating an image with a secret diagram and saving it as a GIF image.
stegShow.tcl Displays a hidden image.