Crappy Desktop Wallpaper Compression in Windows 7

This is a problem I noticed many months ago, but did not seriously look in to until just now.

I like to use the monthly Mozilla Foxkeh desktop wallpaper.  Right now, I have the January 2011 wallpaper — this nice, large, lossless PNG.  (By the way, the word that he is in the progress of writing is “火狐”, which literally means “fire fox.”  How cool!)

Anyway, I noticed that there is crappy compression on the image shown on my desktop, particularly around the numbers that make of the calendar.  This has been occurring in the wallpapers for past months as well.  If I open up the PNG (that I told Windows to use!!) and zoom way in, the image is crystal clear.  But on the desktop, it is junk.  Take a look, I zoomed in on the “2011″ at the top-left of the calendar.  On the left is the data from the PNG as viewed in any decent graphics application, and on the right is what appears on my desktop.

Yuck!

Now, with perhaps more typical wallpapers like photographs, maybe this wouldn’t be so noticeable.  But this is still dumb.  If I provide a lossless image, why can’t Windows use it directly, or at least convert it for use in a lossless manner?

I happen to know that in the registry, the path to your current wallpaper is located at HKCU\Control Panel\Desktop\Wallpaper.  Taking a look at the value stored there…

That’s right, it is pointing at TranscodedWallpaper.jpg, located in the depths of my user profile.  So, Windows took my PNG and converted it to JPEG to be used as my wallpaper.  Ugh.  Ugh ugh ugh.

Anyway, there’s a couple of ways around the problem.  First, you can open the PNG image in Internet Explorer or Firefox or Windows Live Photo Gallery (or perhaps any number of other applications), right-click on it, and select the option to use it as your desktop background.  It will be properly set, without the crappy compression occurring.  (I normally set it through the control panel you get by right-clicking your desktop and clicking “Personalize.”  I confirmed that going back there to set it restores the crappy JPEG compression.)

The other option would be to convert the image to BMP and set the path to it manually in the registry, at the value shown above.  Then, log out and log back in to have Windows notice that the wallpaper has changed.

Hopefully this will be addressed in the next major Windows release!  (Not addressed in the forthcoming Windows 7 Service Pack 1, sorry.)

7 thoughts on “Crappy Desktop Wallpaper Compression in Windows 7”

  1. The probable reason behind this wallpaper image compression is something to do with MEMORY USAGE. For slideshow intentions, mass-converting the wallpapers you want to use to BMP (and replacing their respective file extensions to JPG) is of great help.

  2. My background files are compressed no-matter-what. I can post the actual high quality .png in the windows photo viewer file under app data, compressed. I can right click and set as background while I’m in the Windows photo viewer (viewing the image without artifacts), boom artifacts now. I’ve even tried renaming it .jpg and .jpeg, artifacts!!! Why am I forced to have a crappy quality background on my HD monitor???

  3. I do trust all the ideas you’ve offered on your post. They are very convincing and will definitely work. Nonetheless, the posts are very brief for novices. May you please extend them a little from subsequent time? Thank you for the post.

  4. @cknoerndel:

    This doesn’t seem to be completely true. I’m on Windows 8 RTM and I’m using a JPEG wallpaper. I’ve verified that the file I selected and the file that Windows is using (which is in C:\Users\Aaron\AppData\Local\Microsoft\Windows\Themes\…) are identical. So, it is still not recompressing *some* JPEGs.

    That said, I haven’t done any checking to see if the situation is improved at all but I highly suspect that it has not. I’ve turned my attention to customizing the lock screen background beyond what is possible from the limited control panel. Made some progress that allows for rotating lock screen backgrounds. Topic for a future post. :-)

  5. A late reply to your final statement: “Hopefully this will be addressed in the next major Windows release!”

    Actually Windows 8 will make the matter worse.

    In Windows 7 you could save your wallpaper as a jpg with very low compression -or- save the wallpaper as a bmp and rename it to jpg. Windows 7 recognized the file ending and would not recompress the file, since it thought “it already is jpeg”. This way you could trick Windows 7 into using uncompressed images while still using the built in wallpaper dialogs of Windows.

    In Windows 8, ALL image files get compressed, even files that already are jpegs. Your regedit trick still works somewhat, but none of Windows’ wallpaper functions (shuffling through multiple wallpaper for example) will work if you handle wallpapers through the registry setting.

    A big thanks to microsoft.

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