How to identify photoshop by pixels?

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mi_trandil2016-01-23 22:47:53

Design

mi_trandil, 2016-01-23 22:47:53

There is such a site imageedited.com , its essence - it shows whether the image has been changed in any programs. Surprisingly very accurate and high quality.
But the most interesting thing is that he somehow analyzes pixels or something like that.
When analyzing a picture saved in any program, it displays a message - Pixels only match software editors.
Moreover, deleting exif and other information does not help)
As well as changing the resolution of the picture does not affect this parameter.
The question is - how does this site analyze the pixels? Where can you read about it?
Maybe you have come across this definition "Pixels only match software editors"

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6 answer(s)

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vasiliev, 2016-01-28
@vasiliev

The easiest way, of course, is to determine the change by the Exif metadata.
However, there are approaches to change detection directly from the pixel matrix. None of the approaches gives a 100% probability of detecting all changes, however, for most cases, one or more algorithms will be sufficient. Changes can be detected, for example, by detecting recompression by the JPEG algorithm of individual blocks. You can read about other methods, for example, in this article www.cs.dartmouth.edu/farid/downloads/publications/...
Judging by what is written on the imageedited.com/about.html page , at the level "Pixel Level Tests " some algorithms are applied just from the field of Forgery Detection.

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MiiNiPaa, 2016-01-23
@MiiNiPaa

how does this site analyze pixels? Where can you read about it?

Have you tried it on the site?

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Dimonchik, 2016-01-24
@dimonchik2013

it checks for a sucker - if the picture changed after the camera
after the editor, of course, it is almost impossible to determine, all these "border smoothing" can leave the camera, depending on the algorithm

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Teacher, 2016-01-23
@MrTeacher

Look here

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Vasily, 2016-01-24
@Foolleren

I checked the image that was photoshopped and saved by Photoshop, I determined it correctly, but I couldn’t determine anything at all when resaved in bmp paint - no analysis by pixels, only the data that the program itself left

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Curly Brace, 2016-01-26
@stasuss

editors leave their names in the meta-date. heck why. I even saw it from Gimp. you can look at it corny by opening a small picture in a text editor