Interesting. In that case, do you know why they talk about reviews only seeing "visual derivatives" (from the second perceptual hash)? Either these 'derivative

Interesting. In that case, do you know why they talk about reviews only seeing "visual derivatives" (from the second perceptual hash)? Either these 'derivatives' basically contain the original image (so reviewers can verify that it's actual CSAM) and there's no point in using derivatives at all, or they're more abstract (eg. 8x8 pixellated images) in which case the reviewer can't see the actual content (but could confirm a database match). Edit: I was able to find the answer, they suggest that the 'visual derivative' is something like a 'low-resolution version' of the original image, so the content should still be clearly visible.