| Re: Mac 32 bit color depth? [message #24303 is a reply to message #24241] |
Tue, 20 March 2001 11:52   |
btt
Messages: 345
Registered: December 2000
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Senior Member |
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Hi,
Yes, I can confirm this behavior on a Mac G4 running system 9.04:
!P.Color = 256L^(depth /8) - 1
!p.color = -1
!P.Color = 256L^((depth < 24) /8) - 1
!p.color = 16777215
** Structure !VERSION, 7 tags, length=44:
ARCH STRING 'PowerMac'
OS STRING 'MacOS'
OS_FAMILY STRING 'MacOS'
RELEASE STRING '5.4'
BUILD_DATE STRING 'Nov 1 2000'
MEMORY_BITS INT 32
FILE_OFFSET_BITS
INT = 32
I don't understand the meaning of 32bit displays. It is possible to have
32 bit depths on Windows platforms also. I don't have a Windows machine
handy with IDL5.4, but it would be nice to see the results of the above
on those machines.
It maybe unrelated to what your asking, but note that David posted the
following recently (see Pavel's post on 'Open file in 5.4'):
> What I have noticed is that on a 32-bit display, it
> seems almost impossible to flip back and forth between
> Device, Decomposed=0 and Device, Decomposed=1. What is
> the best way to be able to display either a 24-bit or
> an 8-bit image? It seems to me the color table vectors
> have to be re-loaded every time you set Decomposed=0.
> Is this what you recommend?
Ben
Wayne Landsman wrote:
>
> I have a simple program that tries to reset the default value of
> !P.COLOR for the current (Mac, Win or X) device using the following
> code:
>
> device, get_visual_depth=depth
> !P.Color = 256L^(depth/8) - 1
>
> I am told that this fails on IDL V5.4 on a Mac since
> device,/get_visual_depth returns a value of 32 (whereas !P.COLOR is
> 256L^24 -1). Can other Mac users verify this? What is the meaning
> of a 32 bit visual depth?
>
> Thanks, --Wayne
>
> Wayne
> Landsman
> landsman@mpb.gsfc.nasa.gov
--
Ben Tupper
Bigelow Laboratory for Ocean Sciences
180 McKown Point Rd.
W. Boothbay Harbor, ME 04575
btupper@bigelow.org
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