Zipped image file

[Angelo Graziosi]

Suppose one uses bzip2 to compress a PNG file, foo.png ---> foo.png.bzip2. 
Visiting this file, Emacs says that cannot display the image because cannot 
determine the image type. The file is shown using (Fundamental Image) mode and 
only its codes are displayed (something like '\123'). Is this to be expected 
(master build)? I think it is decompressed but only its 'textual' nature is 
displayed not the image. Is there a command M-x ... I can use to convert that 
'text' in image?

With text file, for example, visiting foo.txt.bzip2 works, the file is 
decompressed and readable.

Thanks,
  Angelo.