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

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.


Liam E. Gumley
Space Science and Engineering Center, UW-Madison