Opened 7 years ago
Closed 5 years ago
#6817 closed defect (wontfix)
gdaladdo produces artefacts in TIFF internal masks for certain resampling schemes e.g. lanczos
Reported by: | nowakr | Owned by: | warmerdam |
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Priority: | normal | Milestone: | closed_because_of_github_migration |
Component: | default | Version: | 2.1.3 |
Severity: | normal | Keywords: | overview, resampling, gdaladdo |
Cc: | mojodna |
Description
When adding overviews to TIFFs that have internal masks using a resampling scheme such as lanczos the internal masks on the overviews (not the image itself) sometimes have significant artefacts well within the nodata area. These artefacts are not created when using average or nearest resampling.
Is it possible that the overview algorithm uses the same resampling scheme on the mask as for the image, thereby leading to ringing on the sharp edge of the mask? (and making non-zero values where there should be zeros)
If this is the case, it makes no sense to always apply the same resampling algorithm to the mask as to the image. The mask should probably be resampled using average regardless of the user choice of image resampling. (Or let the user decide which mask resampling is used by a new command line switch.)
The attached TIFFs have overviews added with lanczos and average schemes, and screenshots of both when zoomed out (to show the overview rather than the primary image).
Attachments (4)
Change History (6)
by , 7 years ago
Attachment: | test_lanczos.tif added |
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by , 7 years ago
Attachment: | test_lanczos - screenshot.png added |
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screenshot of artefacts in internal mask of overview after lanczos resampling
by , 7 years ago
Attachment: | test_average - screenshot.png added |
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screenshot of overviews after average resampling - there are no artefacts in the nodata area
comment:1 by , 7 years ago
Cc: | added |
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comment:2 by , 5 years ago
Milestone: | → closed_because_of_github_migration |
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Resolution: | → wontfix |
Status: | new → closed |
This ticket has been automatically closed because Trac is no longer used for GDAL bug tracking, since the project has migrated to GitHub. If you believe this ticket is still valid, you may file it to https://github.com/OSGeo/gdal/issues if it is not already reported there.
with lanczos overviews