Visual cryptography is a cryptographic technique which allows visual information (pictures, text, etc.) to be encrypted in such a way that the decrypted information appears as a visual image.
This program allows the user to generate n shares of an image, and only by overlapping all n shares the initial image can be seen. To create an 5-5 scheme on an input.png image with a custom expansion of 16 subpixels arranged in 4x4 quads simply use this:
python loki.py input.png 5 --subpixels 16 --stride 4
The default pixel expansion is the lowest possible, 2 ^ (n - 1), and the stride used to rearange the subpixels in a quad is isqrt(expansion factor) Use --help for the other settings.