←back to thread

382 points DamonHD | 1 comments | | HN request time: 0.402s | source
Show context
lynndotpy ◴[] No.43697899[source]
> Years ago it would've required a supercomputer and a PhD to do this stuff

This isn't actually true. You could do this 20 years ago on a consumer laptop, and you don't need the information you get for free from text moving under a filter either.

What you need is the ability to reproduce the conditions the image was generated and pixelated/blurred under. If the pixel radius only encompasses, say, 4 characters, then you only need to search for those 4 characters first. And then you can proceed to the next few characters represented under the next pixelated block.

You can think of pixelation as a bad hash which is very easy to find a preimage for.

No motion necessary. No AI necessary. No machine learning necessary.

The hard part is recreating the environment though, and AI just means you can skip having that effort and know-how.

replies(4): >>43697947 #>>43698101 #>>43698597 #>>43698629 #
nartho ◴[] No.43698597[source]
Noob here, can you elaborate on this ? if you take for example a square of 25px and change the value of each individual pixels to the average color of the group, most of the data is lost, no ? if the group of pixels are big enough can you still undo it ?
replies(6): >>43698743 #>>43698999 #>>43699022 #>>43699023 #>>43699026 #>>43711797 #
porphyra ◴[] No.43699022[source]
Yeah most of the information is lost, but if you know the font used for the text (as is the case with a screencast of a macOS window), then you can try every possible combination of characters, render it, and then apply the averaging, and see which ones produce the same averaged color that you see. In addition, in practice not every set of characters is equally likely --- it's much more likely for a folder to be called "documents" than "MljDQRBO4Gg". So that further narrows down the amount of trying you have to do. You are right, of course, that the bigger the group of pixels, the harder it gets: exponentially so.
replies(1): >>43699045 #
1. lynndotpy ◴[] No.43699045[source]
Yeah, a screencast of a MacOS window is probably one of the best case scenarios for this.