Changing the look of open source apps is relatively easy. All you need to do is to download the source, add new images, and compile. Things get more complicated when the application’s author does not provide the source code and the app needs to be decompiled and recompiled using something like APKtool.
Aware of this situation, the XDA Forum Member Ankush menat created a tool to ease the process of changing the look of your favorite apps. This Windows-only tool allows you to modify application contents by extracting them to a specified output folder. Then, you can use popular applications like Gimp or Photoshop to edit the PNG files. After you’re done editing, you recompile the application and push it back to your device through ADB (or simply install it for non-system apps). The tool creator also provides a short guide on using the utility. The only things you need to use this tool are Windows OS and Java Runtime Environment 6 or 7.
More information and download files can be found in the original thread. So if you’re looking for a way to change the look of your favorite applications, go there and give this a shot._________