Go SMS Pro - Contact picture change (For unknown or default contacts)

[Liderz]

Hi, I'm doing some editing on some themes on Go SMS Pro;
It has this option to change font style, size, color etc etc
on any theme installed.

So, here's the thing. At all theme files I checked, the default
contact picture (Or what they call 'unknown picture' from phone.apk)
are usually using the default silhouette guy look.

I encountered a theme called 'GO SMS STEELBLUE' made by TeamCarbon. This theme, on the other hand, managed to change the default contact pic after I installed it. It managed to change the silhouette guy to another image(A blue epic android).

I'm just wondering how to edit contact images/pictures.
May be it be an app, or something as manual as extracting-compiling a theme file. Anything would be fun and cool.

Any help would be appreciated. Thanks!