Andrea,
Le 20/09/2021 à 11:11, Andrea Giudiceandrea via gdal-dev a écrit :
Hi devs,
gdal_transalte has an "hidden" feature (not mentioned in the docs
[1]), introduced since GDAL 1.10 [2], which allows to convert .JPG +
.JPW raster layer to GeoTIFF without decompressing and recompressing
the raster image (a so called "lossless conversion of JPEG into
JPEG-in-TIFF" [3]).
It seem to me the same is not possible if the source is a .TIF (e.g. a
JPEG-in-TIFF) + .TFW raster layer. In this case the image is always
decompressed and then recompressed if a compression method is
specified, thus adding another unnecessary lossy step.
I think the decompression / recompression cycle should obviously not
be needed converting a TIFF file to a GeoTIFF file (unless image
manipulation options are specified) and gdal_transalte should just
copy the source TIF file and add the proper GeoTIFF metadata tags
taken from the TFW file and from the -a_srs parameter.
Maybe is there any other "hidden" feature I haven't been able to find
yet?
No, this is not implemented. As you mention below gdal_edit, you could
likely do a small script (or an enhancement of gdal_edit that has a
-worldfile {filename} option)) to call SetGeoTransform() with a
geotransform computed from the worldfile content
Best regards.
Andrea Giudiceandrea
[1] https://github.com/OSGeo/gdal/issues/4510
[2]
https://github.com/OSGeo/gdal/commit/a77c726484d508f1ffff2b9f5a9a869313092687
[3]
https://erouault.blogspot.com/2014/04/advanced-jpeg-in-tiff-uses-in-gdal.html
Side notes:
I know gdal_edit could also be used, but it cannot automatically take
the georeferencing parameters from the TFW file.
It could also be possible to use the geotifcp cli tool from
libgeotiff, but it seems it (the one shipped by OSGeo4W) has some
issues handling JPEG-in-TIFF files (while it works well with other
compression formats): the "Warning, fractional scanline discarded."
and "JPEGLib: Application transferred too few scanlines." errors are
reported unsuccessfully trying to convert a JPEG-in-TIFF + TFW to a
GeoTIFF.
Instead, the very old and almost nowhere to be found GeoTiffExamin gui
tool can just add the proper GeoTIFF metadata tags, taken from the TFW
file, to a TIFF file without modifying the raster image. Anyway the
gui tool cannot be used for batch conversion.
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