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| Re: How to do efficient overlay with IDL ? [message #22053 is a reply to message #22045] |
Mon, 16 October 2000 00:00  |
Craig Markwardt
Messages: 1869
Registered: November 1996
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Senior Member |
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"Jean Luc MAILLART" <jeanluc.maillart@wanadoo.fr> writes:
...
> This kind of method is not very efficient under 256 colours, and is
> dramaticaly slow under full colors display, and limit the ability to deal
> with real-time processing (50 or 60 frames/sec).
>
> Is somebody knows :
>
> 1) Why IDL is dramaticaly slower in full colors (3 to 4 time more than in
> 256 colors !) ?
>
> 2) Others more efficient methods to deal with overlays informations on IDL ?
Memory bandwidth is probably killing you. It's not clear to me that
*any* program can do 50-60 frames/sec. It depends on the image size,
which you don't say. It takes time to transfer the bytes to the video
memory buffer, and that time may be too long for you. You might want
to write a sample program in straight C to see the maximum bandwidth
you can achieve. If there are color conversions then it will slow
down even more.
Wy is true color 3-4 times slower than 8-bit color? My guess is that
it's transferring 3-4 times as much data (24 or 32 bits versus 8 bit).
Craig
--
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Craig B. Markwardt, Ph.D. EMAIL: craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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| Re: How to do efficient overlay with IDL ? [message #22057 is a reply to message #22045] |
Mon, 16 October 2000 00:00 |
Bernard Puc
Messages: 65
Registered: January 1998
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Member |
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Jean Luc MAILLART wrote:
>
> Hello
>
> I have a camera connected with some DLL functions writen in C++ that are
> called by IDL main program.
> The acquired images are processed and displayed with overlays results by IDL
> program.
> Today i use TV ou TVSCL for display, then i use some PLOT procedure with
> specific reserved values in the color table to draw the overlays
> informations. after each frame acquisition.
> This kind of method is not very efficient under 256 colours, and is
> dramaticaly slow under full colors display, and limit the ability to deal
> with real-time processing (50 or 60 frames/sec).
>
> Is somebody knows :
>
> 1) Why IDL is dramaticaly slower in full colors (3 to 4 time more than in
> 256 colors !) ?
>
> 2) Others more efficient methods to deal with overlays informations on IDL ?
I'm not certain about this but I think that if you first create a pixmap
window and use it for your output, then copy the contents of the pixmap
to your screen output, you can improve the speed. I'm sure someone else
on the newsgroup knows more about this.
> Thank's for your help.
>
> Jean Luc Maillart
> France
> jeanluc.maillart@wanadoo.fr
--
Bernard Puc AETC, INC.
bpuc@va.aetc.com 1225 Jefferson Davis Highway #800
(703) 413-0500 Arlington, VA 22202
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