| Re: Device's bits_per_pixel keyword [message #13436] |
Thu, 12 November 1998 00:00 |
Charles Cavanaugh
Messages: 8
Registered: July 1997
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Junior Member |
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<HTML>
Harald,
<P>Thanks for your reply, but does your solution reduce only the file size,
or does it
<BR>also reduce the plot size? I specifically want only the file
size to be reduced.
<P>According to the IDL 5.0 Reference Guide Volume 1, on page 74, in the
<BR>BITS_PER_PIXEL keyword explanation :
<P><I>"IDL is capable of producing PostScript images with 1, 2, 4, or 8
bits per pixel. Using more</I>
<BR><I>bits per pixel gives higher resolution at the cost of generating
larger files.</I>
<BR><I>BITS_PER_PIXEL is used to specify the number of bits to use."</I>
<P>I interpret that to mean bits_per_pixel has something to do with the
size of the PS output.
<BR>Do I misunderstand you or the keyword explanation?
<P>Charles
<BR>
<BR>
<P>Harald Frey wrote:
<BLOCKQUOTE TYPE=CITE>bits_per_pixel has nothing to do with the size
of the PS output, it is
<BR>just the number of bits that is adjusted to each pixel and allows
<BR>display in black/white or in any of 255 grey-levels. You have to use
the
<BR>xsize and ysize keywords.
<P>set_plot,'ps'
<BR> device,xsize=15.,ysize=15.,xoffset=3.,yoffset=5.,scale_facto r=1.,bits=8,/color
<P>.
<BR>.
<BR>device,/close
<P>Harald
<BR>hfrey@ssl.berkeley.edu</BLOCKQUOTE>
<PRE>--
Charles Cavanaugh
MOPITT & HIRDLS Programs
National Center for Atmospheric Research
Boulder, CO, USA
email: cavanaug@ucar.edu
phone: (303) 497-2919
fax : (303) 497-2920</PRE>
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| Re: Device's bits_per_pixel keyword [message #13452 is a reply to message #13436] |
Wed, 11 November 1998 00:00  |
Harald Frey
Messages: 41
Registered: March 1997
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Member |
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Charles Cavanaugh wrote:
> I have a program that generates color postscript plots, and I want to
> make the files
> smaller. I have tried :
>
> set_plot, 'PS'
> device, bits_per_pixel = 2
> .
> .
> .
> device, /close
>
> but the file generated is only very slightly smaller than when I do
> not use the
> bits_per_pixel keyword. I've also tried bits_per_pixel = 1, 4 and 8,
> but the file
> size change is so very slight (and in some cases larger then when the
> keyword
> is not used).
>
> If anyone has been able to generate considerably smaller postscript
> files by using
> the bits_per_pixel keyword, please let me know how to do that. Thank
> you.
>
> I'm using IDL 5.1 on an SGI workstation running IRIX 6.5.1.
>
>
> Charles
>
> --
> Charles Cavanaugh
> MOPITT & HIRDLS Programs
> National Center for Atmospheric Research
> Boulder, CO, USA
> email: cavanaug@ucar.edu
> phone: (303) 497-2919
> fax : (303) 497-2920
>
>
bits_per_pixel has nothing to do with the size of the PS output, it is
just the number of bits that is adjusted to each pixel and allows
display in black/white or in any of 255 grey-levels. You have to use the
xsize and ysize keywords.
set_plot,'ps'
device,xsize=15.,ysize=15.,xoffset=3.,yoffset=5.,scale_facto r=1.,bits=8,/color
.
.
device,/close
Harald
hfrey@ssl.berkeley.edu
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