dear all
Im having some issue when applying PROCESSING "RESAMPLE=AVERAGE" or
"RESAMPLE=BILINEAR" on some geotiff with transparency.
Either a clear or dark artifact appears on the border of the image, as
seen on these examples:
http://dev.camptocamp.com/files/mapserver/fuzzy_edge_AVERAGE.png
http://dev.camptocamp.com/files/mapserver/fuzzy_edge_BILINEAR.png
if I specify no PROCESSING at all, the transparency is correct (but not
the image "quality" which I wanted to improve with the PROCESSING ):
http://dev.camptocamp.com/files/mapserver/fuzzy_edge_NOPROCESSING.png
at first I though the problem may have been caused by a fuzzy edge on
the transparent edges in the geotiff:
http://dev.camptocamp.com/files/mapserver/fuzzy_edge.png
so I retreated one image to have clean edges:
http://dev.camptocamp.com/files/mapserver/clean_edge.png
but I couldnt see much difference in the result:
http://dev.camptocamp.com/files/mapserver/clean_edge_AVERAGE.png
http://dev.camptocamp.com/files/mapserver/clean_edge_BILINEAR.png
there is no visible artifact for all border multipe of 90° (horizontal
and vertical edges), only the non 90° edges show that problem.
Im not knowledgeable with image manipulation and resampling with
transaprency, so I dont know if this is normal or not.
Any idea if there is some way to "solve" this "problem" ?
thank you for your attention
best regards
Oliver
--
Camptocamp SA
Oliver Christen
PSE A
CH-1015 Lausanne
www.camptocamp.com
+41 21 619 10 23 (direct)
+41 21 619 10 10 (centrale)
+41 21 619 10 00 (fax)
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