| Re: transparent symbols [message #74934] |
Tue, 08 February 2011 10:43  |
manodeep@gmail.com
Messages: 33
Registered: June 2006
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Member |
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On Feb 8, 10:10 am, bing999 <thibaultga...@gmail.com> wrote:
> On Feb 8, 4:48 pm, bing999 <thibaultga...@gmail.com> wrote:
>
>> Hi,
>
>> I want to overplot symbols (filled circles) on a previously drawn
>> figure. To make it easier to read, I would like to make the symbols
>> transparent.
>> Is there a way to do that?
>
>> Thanks a lot!
>
>> cheers
>
> And please note that I would like to save the plot in PostScript... :)
While the new IDL graphics system has the capability to produce
transparent symbols etc, you still can't save the plot directly into a
postscript format (transparent regions will become opaque). You will
have to first save the plot in a png format and then convert to ps/
eps.
Overplotting on a previously-drawn image is a whole different issue.
Either ask the "supplier" (as Reimar suggested) or extract the data
from the plot using something like Dexter (http://dc.zah.uni-
heidelberg.de/dexter/ui/ui/custom/).
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| Re: transparent symbols [message #74960 is a reply to message #74939] |
Thu, 10 February 2011 11:53  |
pgrigis
Messages: 436
Registered: September 2007
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Senior Member |
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On Feb 8, 11:10 am, bing999 <thibaultga...@gmail.com> wrote:
> On Feb 8, 4:48 pm, bing999 <thibaultga...@gmail.com> wrote:
>
>> Hi,
>
>> I want to overplot symbols (filled circles) on a previously drawn
>> figure. To make it easier to read, I would like to make the symbols
>> transparent.
>> Is there a way to do that?
>
>> Thanks a lot!
>
>> cheers
>
> And please note that I would like to save the plot in PostScript... :)
What about reading the RGB pixel values in the place you need
the symbols, add 32 (or another suitable value) to the R channel
while leaving the G and B channels untouched. That will create
a red-hued semi-transparent symbol...
Ciao,
Paolo
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| Re: transparent symbols [message #74973 is a reply to message #74939] |
Thu, 10 February 2011 08:55 |
MarioIncandenza
Messages: 231
Registered: February 2005
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Senior Member |
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On Feb 8, 8:10 am, bing999 <thibaultga...@gmail.com> wrote:
> On Feb 8, 4:48 pm, bing999 <thibaultga...@gmail.com> wrote:
>
>> Hi,
>
>> I want to overplot symbols (filled circles) on a previously drawn
>> figure. To make it easier to read, I would like to make the symbols
>> transparent.
>> Is there a way to do that?
>
>> Thanks a lot!
>
>> cheers
>
> And please note that I would like to save the plot in PostScript... :)
Yes, I should add this is actually a limitation in PostScript itself,
it just can't do (semi-)transparency of vector objects. It can do
transparency of rasters, in a limited way, but that's the same as you
making the plot in PNG with an alpha channel and then converting to
PS.
I see a lot of new graphics packages advertise writing directly in
PDF, and PDF is apparently capable of handling semi-transparent
objects. I see that IDL 8.0 can output to PDF as well, now they just
need to provide support for semi-transparent objects.
Useful and/or interesting information here:
https://secure.wikimedia.org/wikipedia/en/wiki/Transparency_ %28graphic%29
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