12-08-2009, 01:55 PM
(12-08-2009, 09:38 AM)GaryCXJk Wrote: Regular PNGs are lossless, they do not alter data when being saved. If this is the case when uploading, then the image hosting site just plain suck dragon balls. PNGs never ever darken by themselves. That's bullshit, and I should know it. I've been doing a lot of research on file formats, as well as it being part of my studies.
Could the program the PNG is opened in have some sort of effect on it? I know from personal experience with MS Paint that if you copied a part of a PNG image and tried to paste it into another, there could be some change in the color data. Not as drastic as between other files, but I have an example...
![[Image: bmptest.png]](/image.php?src=http%3A%2F%2Fimg707.imageshack.us%2Fimg707%2F2956%2Fbmptest.png&hash=e1bf4488fb286dcb4751d948434be649)
I did this when I was trying to figure out in what situations where MS Paint would change the color data. The correct ones were copied and pasted into a 24-bit BMP file and then saved as a PNG. The bottom row, which is not the correct palettes, resulted from pasting the last three images onto a PNG file containing the Purple guy. Notice that the differences are very subtle, but the colors are altered on all three of the ones pasted after the purple guy. However, if I was to copy and paste more images of the purple guy over and over, his color would not change, supposedly because it would have the same palette.
So if you are using MS Paint, color data can be warped in weird ways. However, simply saving a file over and over as a PNG shouldn't change it, as far as I know.