Every time when I apply 4k custom PNG image as desktop background, 3840x2160 resolution gets compressed to system native resolution 1920x1080. The location of the file where the compressed desktop background image is pulled from: "C:\Users\XXXXXXXX\AppData\Roaming\Microsoft\Windows\Themes\CachedFiles\CachedImage_1920_1080_POS4.jpg" The final image quality is heavily degraded in two ways: 1. Original lossless PNG file is transcoded to lossy JPG format. 2. Original resolution 3840x2160 is transcoded to system native resolution 1920x1080. So is there a solution to display 3840x2160 images as desktop background to prevent image quality loss? Second question, is there any way to force the system to use the PNG file format instead of compressed JPG for desktop background image? Regardless of resolution.
I think so, and then? Look I'm just a user who shared an info, not MS not the author of the original routines involved in that. So please share your finding w/o that blaming tone. Somerthing like "THANKS, but didn't help" would be more than appropriate. That said, clearly the whole thing was written with resources in mind, when no one would ever think to waste hundreds of megabytes of memory just to please the eye with a slightly better background image. Quality settings and formats aside is beyond me why you would want the image not resized, clearly if your display is 1920x1080, sooner or later this will be final size of the displayed image. Whatever you can try a different approach. say VLC has the feature to display a movie as background you can test a single frame video built with your image and see how it looks.
Well, there were, in the golden old times, graphics drives that would let you set a virtual desktop size much greater than the physical one. One could have a big background image, but the desktop would scroll. I've not seen this mode for many years now.
Yeah that was almost the norm on early Linux distros, I think the virtual desktop size is still used when dealing with multiple monitors, and, if one wants a virtual desktop larger than the screen resolution is still accepted by the xfree/xorg configuration file(s). In windows it was rarer, but for example my great Olivetti Envision (which was practically the first mediacenter ever) had that option to show a 1024x768 or 800x600 desktop on a standard TV which physically couldn't show more than 640x576 pixels (in Europe) or 640x480 in USA. 800x600 was also available w/o scrolling, trough some lines skipped altogether, leading to some font oddities, but overall working pretty well, especially considering the initial (Trident) drivers were built for Win3x
Technically, it is not possible to show a UHD or 4K wallpaper on an FHD screen without any downscaling. The image consists of 3840x2160 (=8294400) / 4096*2160 (=8847360) pixels, but the FHD screen has only 1920*1080 (=2073600) pixels, exactly one fourth of UHD. Won't fit. That's true for all pixel-based images. For being able to scale desktop wallpapers without any quality loss, they would need to be vector-based images (Scalable Vector Graphics, or SVG). Vectors can be scaled without any quality deterioration whatsoever.