muppet on the gtk-perl mailinglist found the solution ;-)
here's his message (well, at least the solution part ;) ): 

Is the image data actually raw, packed, 24-bit pixels?  If it's in a  
compressed format, you'll have to do incremental loading with a  
PixbufLoader.

/me pokes google for EXIF thumbnail format

According to http://park2.wakwak.com/~tsuruzoh/Computer/Digicams/exif-
+ 
e.html#ExifThumbs the thumbnail will be JPEG or TIFF, not raw bits.

Do this, instead:

   my $loader = Gtk2::Gdk::PixbufLoader->new;
   $loader->write ($data);
   $loader->close ();
   my $pixbuf = $loader->get_pixbuf ();

(That code is from memory, check for yourself to make sure i'm not  
telling lies.)

[download]

It works like a charm now ;-)

to ask a question is a moment of shame
to remain ignorant is a lifelong shame

In reply to Re: How to use pack() with Gtk2::Gdk::Pixbuf by insaniac
in thread How to use pack() with Gtk2::Gdk::Pixbuf by insaniac

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