TVIM display routine on 24-bit displays

[David Williams <d.williams(at)qub.ac.uk>]

Hi, there.

I've recently made the switch (as a user, not as sysadmin!) from a Sun
Ultra running Solaris to a PC running Red Hat 6.2. No big deal, perhaps,
but I'm having to come to terms with using a decent graphics card with
24-bit colour when using IDL (and the various astronomy add-ons like CDS
and SolarSoft).

My problem is this: I used to use a very nifty display routine by Paul
Ricchiazzi called TVIM.PRO, which always did the job brilliantly for me.
It still plots fine on a postscript device, but when you use it to
display an image on your 24-bit colour XWindow, the colour table doesn't
scale nicely. If you're using colour table 0 (greyscale), for example,
to view a 2-D image, then it doesn't scale from black (minimum data
value) to white (maximum data value) as it would under an 8-bit display.

I know that the colour system under 24-bit isn't as straightforward as
under 8-bit, for which (I read) IDL is optimised.

Because so many of my routines (and some of my colleagues') depend on
TVIM and all its nice keywords, does anyone know of a way to make TVIM
display things properly on a 24-bit XWindow? The only kludge I've been
able to get to work so far has been to get our sysadmin to cripple the
machine's display to 8-bit colour, which seems like a rather ham-fisted
way of doing things.

Any help would be _greatly_ appreciated,

thanks for taking the time to read this,

Dave Williams,
Belfast.

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