mapnik/mapnik — Issue #997: RasterSymbolizer incorrect blend of alpha
Author: jamesonjb
Created: 2011-12-21 15:27:19+00:00
State: open

Transparent gdal sourced images (png is what I am testing) are not blending correctly with alpha > 0 and < 1. Results are rendered gray.

For instance a transparent cutout with a 5 pixel 'feathered' border will render a 5 pixel grey border in the final image(scaled to final image size).

See example (gdal png composited layer over another gdal png layer):
http://static.jam3son.com/media/img/2917-1.png

The cutout png source file(s) for testing:
http://static.jam3son.com/media/img/esky.png
http://static.jam3son.com/media/img/esky.png.aux.xml

Using the Windows build found here (thanks! btw):
http://mapnik.org/news/2011/11/29/windows-binaries-progress/

Related? Fixed here?
https://github.com/mapnik/mapnik/issues/589
https://github.com/mapnik/mapnik/issues/674