>open image in mspaint >change one pixel >file size

>>57425484
not compressed

>>57425484
Because the only way to display a clear and distinguished pixel is without compression

>>57425542
>>57425500
I'm trying not to sound retarded since I don't really know the first thing about image compression, but you're saying it decompresses the image and then doesn't compress it back, is that it? If so, why doesn't it?

>>57425635
>but you're saying it decompresses the image and then doesn't compress it back, is that it? If so, why doesn't it?
1. What file type was the image before, what file type after? JPEG, PNG?
2. mspaint has some compression settings that you can't influence, wich might result in the following scenario: you download a shitty JPEG with 50% quality setting (->highly compressed), open it in paint and draw something, paint will now save at 95% (or whatever) quality (->not as highly compressed, better quality, bigger file size)

>>57425673
It's a JPEG, pretty low-res. As for better quality, is that a possibility if I see absolutely no difference whatsoever, even upon close inspection?

File: test.jpg (142KB, 929x766px) Image search: [Google]

142KB, 929x766px

>>57425698
it's possible that the compression artifacts are very small and subtle, i.e. only tiny colour changes

here I saved your image (jpeg quality 87) in mspaint, drew a small black line, saved (jpeg quality 94) and put it in an image diff tool[1]. As you can see in fact a lot has changed, but there's almost no difference visible to your eye

[1] https://huddle.github.io/Resemble.js/

File: 1478520975506 - Kopie.jpg (307KB, 1024x846px) Image search: [Google]

307KB, 1024x846px

>>57425729
OP image after modification for comparison

>>57425739
Alright, I pretty much can't spot any difference, so that's probably what happened. Thanks a lot for the explanation.

immensely simplified, there are 2 ways of saving data:
1:
pixel 1 up through 4 are white, 5 is black, 6 through 8 are white.

2: pixel 1 is white. pixel 2 is white. pixel 3 is white. pixel 4 is white. pixel 5 is black. pixel 6 is white. pixel 7 is white. pixel 8 is white.

>>57425785
there also is discrete fourier transform (and derivatives) which jpeg is using