Just … why?!

It’s a joke.

How does it work?

• Your image gets decoded into four color channels (red, green, blue, alpha).
• This raw image buffer then gets encrypted with AES-128 in ECB mode (in your browser).
• The encrypted image buffer consists of as many bytes as the original buffer.
• The encrypted image buffer gets reinterpreted as four color channels and the result is the image you get to see.

ECB?

ECB is short for electronic codebook, the simplest mode of operation of block ciphers. In ECB mode the plaintext message is devided into blocks of equal size and each block is encrypted individually. As you can see this mode is not very secure, as patterns from the plaintext can appear in the ciphertext. More secure modes take previous blocks into account.

My image turns into junk!

See above. This “filter” relies on weaknesses of the ECB mode of operation. It works “best” on images that contain lots of flat colored areas of the same color.