The IMG package by Jan Nijtmans provides the handling
of several image formats beyond the standard formats in Tk.
The formats supported by Img's are:
    * BMP
    * GIF (with transparency, but without LZW, due to patent restrictions)
    * ico
    * JPEG
    * pcx
    * pixmap
    * PNG
    * ppm
    * postscript
    * sgi
    * sun
    * tga
    * TIFF
    * window
    * XBM
    * XPM