image transforming web proxy?

[Skip Montanaro]

I stumbled upon an old FFT tutorial on astro.berkeley.edu website
whose images are in xbm format.  Neither Chrome nor Firefox knows how
to display X bitmap format and for Chrome at least, I've been unable
to find an extension to do the conversion (didn't hunt for a FF
extension).  I can clearly download the whole kit-n-kaboodle, use any
of a number of different tools to convert the images from xbm to png,
then view things locally.  I finally figured out that Opera supports
xbm and downloaded it.

I wonder though, if there is a Python-based web proxy out there which
can transparently transform "obsolete" image formats like xbm into
png, jpeg, presumably using PIL?

Thanks,

Skip