[gdal-dev] GDALwarp creates some darker images after update from 1.7.0b2 to GDAL 1.11.0

[Even Rouault]

Marcel,

The best would be that you prepare something that others can try in a fully 
reproducable way, i.e. provide source(s) image(s) and all the exact command 
lines you use.

Even

Le vendredi 26 septembre 2014 19:41:01, Marcel Blom a écrit :
> Because of some problems with GDAL 1.7.0b2 in FWTools 2.4.7 I upgraded
> to GDAL 1.11.0 in the latest OSGeo4W distro. This solved some issues I
> had, but introduced a really annoying one and what ever I do I can't get
> rid off it. I hope someone can help me out. If BTW I try to go back to
> GDAL 1.7.0b2 with FWTools the problem is still there, so I guess it's a
> (new) driver/DLL update issue.
> 
> My problem looks exactly like this post... GDAL TIF to JPG Creates Dark
> Image
> <http://gis.stackexchange.com/questions/101393/gdal-tif-to-jpg-creates-dark
> -image> Only that I don't use JPG. And I use GDALwarp. And not all target
> files have the problem. Most target files look OK. And I only see it with
> Aerial Photo like sources. With vector like raster sources I don't see the
> problem. So when reading the other post I thought it had to do with a
> mask/alpha channel or something, but I can't see this in the source. And
> whatever option I test, the problem remains.
> 
> I already created a post here :
> http://gis.stackexchange.com/questions/114526/gdalwarp-creates-darker-targe
> t-image-sometimes But I had no final answer... And I think this is the
> right place to ask.
> 
> Here are two screenshots. One from the source (Tiff) and one from a
> intersection of four target files (Tiff or BMP)
> 
> Section of Source :
> https://www.dropbox.com/s/gy2tu0h8dufv41o/Source.jpg?dl=0
> 
> Intersection of four Target files :
> https://www.dropbox.com/s/av7mdj8ivx3zgsl/Target.jpg?dl=0
> 
> The source I use is 8bit/channel RGB JPEG. And the merged Tiff is
> 8bit/channel RGB.
> I tested almost all options in multiple actions in my workflow. So
> cutting the source with gdaltranslate in smaller parts for editing.
> Building a VRT with gdalbuildvrt and cutting into final parts with
> gdalwarp which will show the problem.
> 
> I started with the -b 1 -b 2 -b 3 option in my gdalbuildvrt action, but
> GDAL crashes here... (?) I also tested other options that might have
> something to do with the problem... -nomd -co ALPHA=YES/No -co
> PHOTOMETRIC=RGBA/RGB -setci, you name it...
> 
> I checked good and bad source and target areas with gdalcompare and
> gdalinfo, but I saw nothing strange...
> 
> I'm now thinking of resetting GDAL driver settings if that is possible..(?)
> 
> Has anyone seen this before? Can anyone give me a hint..?

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