Comment by lucb1e

> In fact, I used gaussian blur to redact some private information

Absolutely never do that. I honestly don't understand why people still do, given that it's obvious that low levels of blur can be reversed why even risk guessing until what point someone might be able to recover anything? Just censor it, draw over it with an opaque tool, and save it in a format that won't store layers or undo history or something (the riskiest format being pdf).

If you don't like how that looks, the alternative is to replace the information and then blur it. They can unblur but will find an easter egg at best.

Personally, I censor instead of blurring a replacement, but I balance between low contrast and not hiding the fact that information was removed. A stark contrast distracts and looks ugly. E.g., for black text on a white background, I'd pick a light/medium gray (around the average black level of the original text, basically).