If you like to set high quality wallpapers as background images on your desktop you may have noticed that Windows compresses the pictures automatically when you do. What the operating system does is compress the image, likely to save space so that the system loads faster after sign in.
Most Windows users may not even notice that Windows is doing so, as it depends highly on the selected wallpaper image and operating system used. The compression is used in all operating systems starting with Windows Vista, but the way it is implemented has changed significantly with each system.
There is no switch to turn the feature off in Windows, but there are a couple of workarounds that you can try to avoid that your wallpaper images get compressed in the process.
Take a look at the following two screenshots. They show the same picture set as the background in Windows 8. The first shows clear signs of artifacts, while the second does not.
I have used the same source image both times, so why the quality discrepancy? The first image was set directly from Internet Explorer 10 with a right-click on the image and the selection of "Set as background" from the browser's context menu. The second was saved first to the computer, and then set as the background from Windows Explorer.
The images have not been modified in any way or form prior to this.
1. Save to desktop first
Instead of using the browser's set as background option, try to save the picture to the local PC first. Use the default file manager to set it as the background, or the personalize screen. This resolved the issue on the Windows 8 PC that I tested various options on.
While this may work at times, it did not work out for all users who encountered the issue.
2. Convert to PNG or BMP
If your source image is a jpg, try converting it to png or bmp format instead before you set it as your background wallpaper. You may need to experiment with various ways to set it as your system's wallpaper though. Some users reported that you need to load it in Firefox or another browser (the local converted image), to set it as the background image without compression.
You can use Paint or any other image editor to convert the jpg image to png or bmp. Just right-click it and select Edit. In the image editor use the Save As option to save
3. Replace the compressed wallpaper
Windows saves the compressed wallpaper image that it creates in the C:\Users\%USERNAME%\AppData\Roaming\Microsoft\Windows\Themes folder on the system. It is stored as TranscodedWallpaper in the folder.
4. Make sure the resolution fits exactly
You best use an image that has the exact same resolution as the screen resolution of the connected monitor. What you can try as well is to set the DPI setting to 72.009 dpi and 8bit.
You can use programs such as Adobe Photoshop, Irfanview or XnView for that.
Some images are not affected by the compression regardless of their original format, while others seem to be compressed no matter what you try. It may take quite some testing and trying out before you find a solution that works for the images that you want to set as your wallpaper on your system.
Have you encountered the issue before? If so, did you manage to resolve it?
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