| Re: Black background in IDL 8.1 map projections? [message #77771] |
Mon, 26 September 2011 10:45 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Mark Piper writes:
> Yes, as nata explains, this is a consequence of how PostScript handles
> transparency.
>
> The workaround is to set BITMAP=1 when saving the graphic.
> Unfortunately, this explodes the file size.
>
> For future reference, this is logged as CR 62485.
While we are logging bugs, am I correct that the LANDSCAPE
keyword has no effect whatsoever on the PostScript output
in this (supposed!) workaround? This command, for example:
IDL> w.save, 'imgmap.ps', BITMAP=1, $
HEIGHT=5*600, WIDTH=8*600, /LANDSCAPE
seems only to produce an encapsulated PostScript
file (despite the fact this is not what I want!)
in Portrait mode.
Cheers,
David
P.S. I note that by using the HEIGHT and WIDTH
keywords I can reduce the normal PostScript file
size of 84 MBytes to a more manageable 46 MBytes. ;-)
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")
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| Re: Black background in IDL 8.1 map projections? [message #77776 is a reply to message #77771] |
Mon, 26 September 2011 08:48  |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Mark Piper writes:
> Yes, as nata explains, this is a consequence of how PostScript handles
> transparency.
>
> The workaround is to set BITMAP=1 when saving the graphic.
> Unfortunately, this explodes the file size.
>
> For future reference, this is logged as CR 62485.
OK, just so I understand. I can't do anything about saving
the PostScript file from the graphics window. If I understand
correctly, it *always* does BITMAP=0. But, I could,
presumably, use the SAVE method on the visualization
object (assuming I can get it out of my program!) and
save it that way with BITMAP=1.
Is that the gist of it?
Cheers,
David
P.S. And I presume, since I have to do this by hand
anyway, that this is where I would make the PostScript
output actually fit on a sheet of paper. Is that correct?
If so, how would I do that?
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")
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| Re: Black background in IDL 8.1 map projections? [message #77777 is a reply to message #77776] |
Mon, 26 September 2011 08:35 |
Mark Piper
Messages: 198
Registered: December 2009
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Senior Member |
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On 9/25/2011 7:32 PM, nata wrote:
> I get something similar when I try to save Post Scripts with
> transparency. PS does not support transparency and converts the alpha
> channel to black. Sometimes I have 2 IDLgrImages, one with completly
> tranparent pixels over another image. I have to take both images and
> blend them if I want to create a PS. In you case, I don't know how you
> could solve the problem because I don't like NG and I never use
> them :)
>
> nata
Yes, as nata explains, this is a consequence of how PostScript handles
transparency.
The workaround is to set BITMAP=1 when saving the graphic.
Unfortunately, this explodes the file size.
For future reference, this is logged as CR 62485.
mp
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| Re: Black background in IDL 8.1 map projections? [message #77783 is a reply to message #77777] |
Sun, 25 September 2011 18:32 |
natha
Messages: 482
Registered: October 2007
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Senior Member |
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I get something similar when I try to save Post Scripts with
transparency. PS does not support transparency and converts the alpha
channel to black. Sometimes I have 2 IDLgrImages, one with completly
tranparent pixels over another image. I have to take both images and
blend them if I want to create a PS. In you case, I don't know how you
could solve the problem because I don't like NG and I never use
them :)
nata
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| Re: Black background in IDL 8.1 map projections? [message #77785 is a reply to message #77783] |
Sat, 24 September 2011 07:34 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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David Fanning writes:
> At least it was perfect until I tried to save the
> visualization as a PostScript file. Then there is
> a black rectangle that seems to be positioned behind
> the map projection. It doesn't show at all on the
> display, but clearly shows (and won't go away!) on
> the PostScript file. Presumably I didn't see the
> rectangle before because the equirectangular
> projection covers it up.
Here is an example of what I am seeing:
http://www.idlcoyote.com/ng_tips/blackpsbg.php
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thue. ("Perhaps thos speakest truth.")
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