As you all know the background color of the Windows Photo
Viewer in Windows 7 and 8 is white. You can change this color to any color you
want with little change in the registry. This trick only works in Windows 7 and 8. Just
follow these steps:
1. In Win 7/8 press Win + R to open the Run. Type regedit and then hit the Enter key to go
to the Windows registry editor.
2. Go to the path below:
Note: if you couldn't find the above key, just create it yourself.
3. Right-click on an empty space in the right panel and then
select New>DWORD (32-bit) Value.
4. Change your new key's name to BackgroundColor.
5. Double-click on the BackgroundColor and in the new opened window enter your desired color value in HEX. You can Google search for HTML color references or use the site below:
http://www.w3schools.com/colorpicker
When you selected the color that you want, add FF before it and enter the value in the box. For example the color that I choose is 0066FF, so I will enter FF0066FF.
6. Click on OK button and exit from the registry editor. Go to the Windows Explorer and open any image with Windows Photo Viewer to see the changes. To go back to the default value, simply delete the new key you just created.