This a very valid concern. Yes, indeed, the compression might leak out certain bits out to the neighboring pixels. Especially in this sequence: raw -> lossy (jp

This a very valid concern. Yes, indeed, the compression might leak out certain bits out to the neighboring pixels. Especially in this sequence: raw -> lossy (jpeg) -> redaction -> less lossy or lossess (png). Whether that's enough to decode the redacted information will depend on how many pixels were redacted and other intricacies of JPEG. This is not too dissimilar to compression oracle attacks, such as CRIME (https://en.wikipedia.org/wiki/CRIME https://en.wikipedia.org/wiki/CRIME), an infamous vulnerability in HTTPS.