As of Tk4.2, Tk supports XBM (X bitmap) for bitmaps as well as PPM
(portable pixmap, a 24 bit format) and GIF (graphics interchange format)
for `photo images`.  Currently only PPM and XBM support the `-data`
option.

The Tk Image Extension (http://home.wxs.nl/~nijtmans/img.html) by Jan
Nijtmans (mailto:nijtmans@wxs.nl) contains format handlers for XBM, XPM,
JPEG, GIF89, PNG and TIFF and the `pixmap` image type adopted from Tix
(http://tix.mne.com/).  Further image formats can be added via DLLs with
the Tk C command `Tk_CreateImageType` (along with code to read that
format, of course).