| Re: ARG! Direct Color problem IDL 5.5/Linux (decomposed doesn't help) [message #29270 is a reply to message #29183] |
Thu, 07 February 2002 15:16  |
Andrew Cool
Messages: 219
Registered: January 1996
|
Senior Member |
|
|
Jaco van Gorkom wrote:
>
snip
>
> That is the situation for video hardware which handles 32-bit color.
> In 8-bit color hardware (think government-funded research) there can only
> be 256 different colors on the screen at any one time. So if I ask IDL to
> allocate 256 colors, it uses a private colormap. This causes color flashing
> when moving in or out of plot windows and/or draw widgets. Result: when
> looking at a plot window in the correct colors, the black and gray/white of
> the slider bars appear in some of the first 20 colors of the color map.
> Usually black on black. With the mouse on the slider button, the general desktop
> color map is active. Ergo I do not see the plot in the color map I am adjusting.
> Or am I missing something?
>
> Cheers,
> Jaco
I know your problem with the 8bit colour hardware in government-funded
research,
as my mob mainly used IDL under OpenVMS and Xterms for many years.
We gave up allowing the default allocation of 256 colours pretty quickly
too.
These days, most of us here allocate only 64 colours, and of that the
top dozen or
so are set to standard colours like red, orange,yellow,green, etc,
leaving about
50 colours for the actual colour scale.
By allocating only 64 colours, this allows us to open say 3-4 separate
IDL sessions
without any conflicting colour table problems or flashing windows as the
cursor
moves around the screen.
And we're not missing anything in terms of detail. Let's face it, with
256 colours,
can you really tell which shade of lime-green pixelA is, and compare
that exactly
to your colour bar legend? I'd say No - you just get a feel for the
value.
Less can sometimes be more when eyeballing colour plots. Trends in the
data are
just as visible, and you've always got the cursor readout if you need to
reference
pixelA back to the original data.
32 bits to represent 8 bit data might just be overkill ;-)
But then some people describe me as brain dead too.
Andrew
------------------------------------------------------------ ---------
Andrew D. Cool .->-.
Electromagnetics & Propagation Group `-<-'
Surveillance Systems Division Transmitted on
Defence Science & Technology Organisation 100% recycled
PO Box 1500, Salisbury electrons
South Australia 5108
Phone : 061 8 8259 5740 Fax : 061 8 8259 6673
Email : andrew.cool@dsto.defence.gov.au
------------------------------------------------------------ ---------
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
