Opened 13 years ago
Closed 13 years ago
#3821 closed defect (fixed)
gdal_retile.py handles alpha incorrectly (patch)
Reported by: | cdestigter | Owned by: | warmerdam |
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Priority: | normal | Milestone: | 1.8.0 |
Component: | Utilities | Version: | svn-trunk |
Severity: | normal | Keywords: | |
Cc: |
Description
gdal_retile.py doesn't handle alpha channels properly. This results in semi-transparent black shadows when resampling input images. The black borders are more obvious in highly shrunk (ie from high res to low res) output.
EvenR helped me out with the attached patch, which fixes the problem by setting band interpretation correctly in gdal_retile.py, and using it in GDALReprojectImage.
Here's my command line:
rm -r ~/tmp/retiled mkdir ~/tmp/retiled gdal_retile.py -v -co ALPHA=YES -ps 4096 4096 -ot Byte -r bilinear -levels 4 -targetDir ~/tmp/retiled ~/tmp/src-images/0000000*.tif
I'll also attach some tiny RGBA test tiffs which demonstrate the problem. Compare the output in levels 3 and 4 of output before and after patching.
Attachments (2)
Change History (3)
by , 13 years ago
Attachment: | gdal-retile-alpha-fix.patch added |
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by , 13 years ago
Attachment: | gdal-retile-borders-test.zip added |
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comment:1 by , 13 years ago
Component: | default → Utilities |
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Milestone: | → 1.8.0 |
Resolution: | → fixed |
Status: | new → closed |
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r21095 /trunk/gdal/alg/gdalwarper.cpp: GDALReprojectImage() : correctly assign nSrcAlphaBand and nDstAlphaBand (#3821)
r21096 /trunk/gdal/swig/python/scripts/gdal_retile.py: gdal_retile.py : assign color interpretation (#3821)
r21097 /trunk/autotest/ (gcore/data/rgba.tif pyscripts/test_gdal_retile.py): Test gdal_retile.py with RGBA dataset (#3821)