I know, I know, I imagine people are more interested in uncensoring and not the opposite, but since I had to figure it out for submitting content to Japan, I thought it would make for an interesting quick post.
At first I tried to open the files in a paint program with animation support and just edit the images individually, but this quickly became unreasonable, so I hit on another method
First I take the animation and resize it to postage stamp size
This is the source of the mosaic, this way it will move the same as the full animation
Then I take the uncensored animation and place the low res version as a layer behind it, and create a simple flat shape that serves as a “projection target” meaning it shows the hidden layer on top. I animate this shape to follow the animation in order to cover the area that needs censoring
Then ta-da, render time and we have the good old mosaic censoring we know and love
