Re: Q: 8bit color tables in NT 24 bit display

[Liam Gumley <Liam.Gumley(at)ssec.wisc.edu>]

Manuel J Suarez wrote:
> Hi there, can anyone tell me if there is a Windows device equivalent
> to the X  DEVICE, PSEUDO=8 ?

Unfortunately, Windows IDL does not allow this command (it is only
allowed in Unix and Mac IDL). Thus you cannot start an 8-bit Windows IDL
session when you have a 16, 24, or 32-bit desktop.

> I'd really rather not have to change my display through the control
> panel every time I'd like to use color tables.  I need to display 8-bit
> images with a color table and multi-colored plots.

You *can* use color tables in 24-bit mode; you just can't modify them
interactively and have the changes immediately show up in images or
graphics which have previously been displayed. In 24-bit mode, after you
change the color table, you must redisplay the image/graphics for the
color table changes to be apparent.

The other piece of crucial advice is that you should execute the
following command immediately after IDL startup:

device, decomposed=0, retain=2

This puts IDL into un-decomposed color mode with backing store enabled.
You'll be much happier running IDL in this mode (colors will work mostly
the same was as they do in 8-bit mode).

Better still, put this command into a file named idl_startup.pro, and
then point to the file in File|Preferences|Startup, which will cause
this command (and any others in the startup file) to be executed at the
beginning of every IDL session.

Cheers,
Liam.

-- 
Liam E. Gumley
Space Science and Engineering Center, UW-Madison
http://cimss.ssec.wisc.edu/~gumley