Here's a quick tool I put together for adding fake compression artifacts to an image, inspired by the preview image on wikipedia/JPEG.

>>> JPEG painter <<<

It generates a series of 24 images with varying levels of compression from your input, and uses a mask to determine where the compression should be applied. These images are broken up into 8*8 chunks and then recombined based on the mask into the final output, allowing you to selectively paint compression.

I don't have many plans to expand on this, but I figure it's pretty cool for making glitch art and some people might find it useful ^-^

Feel free to take apart the source code and make something better with it, I'd love for this sort of tool to be incorporated into actual art programs and tools. My source code is available here: https://github.com/gitchly/jpeg-painter