You have set as wallpaper in Windows 10 a personal photo of yours, but you are not satisfied with its quality? You can increase it with a simple trick. 
When you define a picture as your desktop background, the image is compressed to 85% and saved to a file named TranscodedWallpaper in the Themes folder (C:\Users\Iguru\AppData\Local\Microsoft\Windows\Themes). Sta Windows 10, you can bypass the default wallpaper compression for JPG files by using the registry. Let's see how:
1. At the same time, press the Win + R keys and in the run window that appears, write regedit and press OK.
2. Go to the following key HKEY_CURRENT_USER \ Control Panel \ Desktop
3. Create a DWORD value that will be called JPEGImportQuality
4. Double click on JPEGImportQuality and set them data value to 100 with a decimal base
5. Close the registry and restart explorer (or computer you, if you don't know how)
You will need to right-click on your personal image and set it as wallpaper again so that the TranscodedWallpaper in the following folder is replaced.
You will see that the size of the TranscodedWallpaper file has increased (as well as image quality) after setting JPEGImportQuality to 100. JPEGImportQuality can accept a decimal range from 60 to 100.
