[OSGeo-Discuss] problem using php's GD to overlay images

[pere roca ristol]

hi all,
I need to overlay two or more images from server-side (PHP) coming from
diferent WMS GetMaps (as I need to create these requests using dynamically
created SLDs for different layers I cannot integrate everything on the same
Getmap). In these GetMaps I include the Transparent=true parameter.

I'm using imagecopymerge from GD php's library to overlay the images. One of
the parameters of this function is a percentage (of pixels of the second
image to be printed over the second image). The problem is that it means
losing brightness.

You can check this URL (as in Mexico there are more than one layer
overlayed, it appears without brightness)
http://edit.csic.es/fitxers/TDWG_distributions.php?ad=tdwg2/c:Brazil,Mexico,Caribbean|b:Mexico||tdwg4/c:Nicaragua,Chiapas,Oaxaca,Veracruz||tdwg3/a:MXC,|b:MXE,MXG|d:VEN|c:MXT,&as=a:d7add2|b:ab8dc9F|c:f2e227|d:f7555d&ms=700x450

Some idea? some similar function in PHP (or not...) to solve it?
thanks!

-- 
Pere Roca Ristol
Biòleg i especialista GIS
Museo Nacional de Ciencias Naturales (CSIC)
Visita l'EDIT mapViewer!
http://edit.csic.es/edit_geo/prototype/edit.html
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