>>7029848>>7028022 sums it up entirely correctly. You are doing yourself a disservice to use jpeg format for your wallpapers.It's always a good precaution to store all your wallpapers in a losslessly compressed format, such as PNG. If you want to be hardcore, use an entirely uncompressed format, like bitmap. But there's no need - bitmap images are huge files, especially at wallpaper size.
PNG is doubly necessary if you use Windows, because if you use a .jpg file as your wallpaper on Windows 8 or higher, the OS will copy your file and compress it even further than it already was before displaying it as your wallpaper, creating more jpeg artifacts when you actually look at your wallpaper than when you look at the original jpeg in an image viewer. But in all honesty, using Windows is almost as bad as using lossfully-compressed jpegs as wallpapers and you should switch to Linux :P
3. Digital noise - also explained in the jpeg compression artifacts article.
>>7027999 - look at the dark shadowy mountain toward the bottom left. You can see the pixels because the different shades of blue don't blend into each other smoothly like they should. This is banding noise.>>7028028 - look at the blue-black darkness in the very upper left cornerThis is probably the least common of these kinds forms of distortion, at least for wallpapers. This one comes up in dark areas and gradient areas a lot - perhaps in digitally generated or doctored images more often than raw photographs.
All three of these kinds of image distortion are easier to find in the corners of wallpapers, where there's often less light and less attention. But if you're using it as your wallpaper, you're gonna notice it eventually.
Sorry for the long comments. I just want to see higher-quality wallpapers on the internet.
