Looking for similar images?

Question

Images

Hello.

Faced with the problem of duplicate images.
When there are two identical images, but one at 500x500 - the other 1000x1000 . Is it possible (and how) to find these duplicates.

And yet, how can you get only those in which the same object is present among thousands of images? (for example, the same logo, the same on all images)

Answer 1

The simplest:
Scale to some standard size (254x254 for example).
We break the grid NxN, into tiles.
We consider the average color in each tile. We write down the color
difference from the next tile (the first one) with a certain threshold of sensitivity.
We get a series of numbers, which can already be called a characteristic of the image.
This is the first thing that comes to mind if the problem needs to be solved quickly and without bothering with fractal image coding.

Answer 2

On the first point - a similar question How to compare two images for complete identity?
and also Search for similar pictures?
Is there a _quality_ program for finding the same and similar images on a hard drive?
How to find similar pictures?
According to the second (logo search, etc.) - completely different methods, this is already for neural networks.