Tags: jpg misc 

Rating: 2.0

# TSGCTF 2020 Poor Stego Guy Writeup

The key point is that `noise.jpg` is saved with the option `-quality 50`. Low-quality jpeg images have very small representation space, and thus the representation space is **sparse**. So, images that are very close to `noise.jpg` are likely to be exactly same as `noise.jpg` after jpeg compression.

We have `output.png`, which is **very close** to deleted `noise.jpg`.

docker run -v `pwd`:/mnt dpokidov/imagemagick:7.0.10-9 /mnt/output.png -quality 50 /mnt/noise.jpg

We get `noise.jpg`.