Yes, but read the post carefully and in context...
I said they are JPGs, PNGs or
GIFs. So, it might be that the image you're trying to open is a GIF.
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Also note that that post has been made 5 years ago. So, I talked about
normal display pictures which you can find in the
UserTile subdirectory. Thus not about the new
deluxe display pictures which you will find in the
DeluxeDisplayPictures subdirectory.
The new
deluxe display pictures which you will find in the
DeluxeDisplayPictures subdirectory are, just like Winks,
Microsoft Cab Files (MSCF) which consist internally of an XML index file (indexing the states it can show), the main Shockwave Flash file, and a PNG thumbnail representation. The normal extension of these archives is
CAB and you can open them with any archiving program which supports MS-CAB files (eg: WinRAR).
PS:
The Winks are actually also MS-CAB files (CAB).
The CustomEmoticons are actually PNGs (PNG) or GIFs (GIF).
The new Dynamic Backgrounds are actually MS-CAB files (CAB).
The new Scenes are actually JPGs (JPG) or PNGs (PNG).
The new Signature Sounds are actually Windows Media Audio files (WMA).