"If you have a point-and-click digital camera made by Canon, you
may be able to turn on all sorts of features usually reserved for
more expensive SLRs. That includes live histograms, depth-of-field
calculation, under and overexposure highlighting, and--best of
all--shooting your pictures in RAW. The secret is CHDK, an
enhanced, free software replacement firmware.
"It is not clear what CHDK developer Andre Gratchev intends the
initials CHDK to stand for, but the user community has speculated
that it means Canon Hacker's Development Kit..."