Copyright, Robert Donovan, LessonStudio, 2014 If you use this then tweet what you did with it @LessonStudio.
This file takes one argument which is a file that you would like to split into two encrypted images. The original image can only be viewed by overlaying the two encrypted images. If printed on clear plastic, It can be very finicky to align the two images if the pixel count is too high. For best results keep the original image below 200x200 pixels and print as large as possible onto clear plastic to obtain the best results.
You can go to higher resolutions but you then really have to be precise when aligning the two images.
The resulting images will be twice as wide and twice as tall pixelwise and there is only 1 bit colour.
Future features should include alignment marks to make aligning the two transparancies easier.
Maybe I will increase the efficiency of the conversion except that I find that I spend more prep time in photoshop by many orders of magnitude than any time savings that could be extracted.
The reason I built this is that I found many tools out there for doing this that didn't work for a variety of reasons including being built for long dead versions of Python.
USAGE: python visual_cryptography.py file_to_encrypt.png