[guide-user] Bill - contrast/brightness

Andre Germain Jan 12, 2000

The Fits Win95 C++ program I wrote for my observatory figures
out the correct contrast and brightness by doing a histogram
and searching from the lowest histogram point upwards and
looking for the longest contiguous bunching of data. There is
of course a threshold which is determine from the density of the
histogram (all counts summed and divided by histogram width).
Any histogram column above this threshold is considered if it
does not sit alone. This will remove spurious pixels, noise, etc.
It works quite well and is a very short bit of code. Primitve,
effective.

In fact, I've used the routine for the stand alone fits display
(when the CCD images are downloaded from the telescope over the
network real time), for a mosaic program (to paste many CCD images
together) and for the bulk fits processor display (dark frame,
flat field, aligning, etc).

Cheers