transparency in printim

[Bernd Becker]

Thanks Jennifer and Patrick!

Patrick Reuter came up with a solution!



after all the rigmarole described in the e-mail below,
one further step does deliver the intended result:

'!convert -transparent black pop.png pop.png'


On Wed, 2009-03-04 at 08:56 -0500, Jennifer Adams wrote:
> 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
> >
> >

'!convert -transparent black pop.png pop.png'

> > 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?

'!convert -transparent black pop.png pop.png'

> > 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
>
>
>
>
>
>
--
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