transparency in printim

[Jennifer Adams]

Hi, Bernd --
I do not have an answer for this problem. I created images with a
transparent color that many applications including Photoshop, Preview,
Safari, and Firefox all treat properly, but Google Earth ... does not
get it right. I have also created images that Google Earth does get
right (the transparent color is indeed transparent and the background
shows through), but I have not been able to figure out what the key
difference is between these images. My GrADS scripts are essentially
the same and so is the KML. After spending a frustrating afternoon
figuring out these things, I stopped playing with Google Earth and
went back to work on something else.
--Jennifer

On Mar 4, 2009, at 7:07 AM, Bernd Becker wrote:

> Hello,
>
>
> to create images to be shown on google earth, I would like to
> create shaded contour plots and contours and  symbols all in one png
> file.
>
> The areas, where nothing is shown in the image, I would like to be
> transparent to see whatever google earth puts underneath.
>
> I do:
>
> 'set parea 0 11 0 8.5'
> 'set grid off'
> 'set mproj scaled'
> 'set x  0.5  321.5  '
> 'set y  0.5  161.5  '
> 'set mpdraw off'
> 'set grads off'
> 'set frame off'
>
> clevels ='  -0.9 -0.5 -0.2 -0.1  0.1 0.2 0.5  0.9  '
>
> 'set cstyle 2  '
> 'set ccolor 1  '
> 'set cthick 1'
> 'set black 'subwrd(clevels,4)' 'subwrd(clevels,5)
> *'set gxout shaded'
> 'set gxout grfill'
> 'set clevs 'clevels
> 'set ccols  14    4   11   5   0   16  7   12  2  '
> 'set black 'subwrd(clevels,4)' 'subwrd(clevels,5)
>
>
> 'd v7  - v6'
>
>
> 'set gxout shaded'
> 'set clevs 'clevels
> 'set ccols  14    4   11   5   0   16  7   12  2  '
> 'set black 'subwrd(clevels,4)' 'subwrd(clevels,5)
> 'd maskout((v8-v6),v1-23.)'
>
>
> 'set gxout shaded'
> 'set gxout contour'
> 'set cthick 1'
> 'set ccols 12 2 '
> 'set ccols 80   80 48  '
> 'set clab off'
> 'set clevs 'thresh
> 'd v5'
>
>
> printim pop.png x320 y160 -t 1
>
>
> Here I am uncertain about which colour code to use:
> the colour number currently set in grads?
> the current color code from the X server?
>
> How can I ascertain, that the regions set to "black"
> by 'set black'
> are transparent in the png file?
>
> These areas are shown as black, so "-t 1"  should do the trick,
> but google earth shows the areas as black, opaque.
>
> What should I do?
>
> Many thanks,
> Bernd.
>
> --
> Bernd Becker   The Monthly Outlook
> Met Office  FitzRoy Road  Exeter   Devon EX1 3PB  United Kingdom
> Tel.: +44 (0) 1392 884511 Fax: +44 (0)870 900 5050
> E-mail:bernd.becker at metoffice.com  -  http://www.metoffice.com

--
Jennifer M. Adams
IGES/COLA
4041 Powder Mill Road, Suite 302
Calverton, MD 20705
jma at cola.iges.org



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