I have invented a bold and revolutionary method in order to compress any picture to only a few bytes (typically more or less one hundred).
Here is how it works in a few words :
It separates the three layers of a picture (RGB, but only stores one specific bit if they are similar).
For each layer, it defines the average brightness.
It divides a picture into a grid, where each cell is either "more light" or "more dark" than the parent average brightness (each is coded in one bit).
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Then it makes two average pictures out of the "light" and "dark" areas, and repeat the operation on them.
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It stops doing this when the picture is smaller than one pixel or the color is solid.
The source code for this is there
This is of course a lossy method, here are a few examples of original and compressed pictures (typically to about 128 bytes in my own .bpc format, converted back to .png here) :
A picture of Abraham Lincoln :
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A baloon :
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A camera :
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A wooden house :
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A flower :
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Some album cover :
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A typical landscape :
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And here is an example of .bpc file. It could probably fit in one tweet.
I didn't know about it back then but it might have something to do with the concept of self-affinity.