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<div class="moz-cite-prefix">Le 24/10/2024 à 15:53, Rahkonen Jukka
via gdal-dev a écrit :<br>
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<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Thanks
Thomas,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"
lang="EN-US">I will suggest an edit to the GeoTIFF driver
page for adding that information.<br>
If single row blocks are needed for some reason, it seems to
be better to use the JPEGXL driver directly. It is fast and
creates small output.<br>
</span></p>
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<p>The single row block reported by the standalone JPEGXL driver is
an illusion. The driver has to decompress the whole image first,
so once it has done that it can expose a single line as the block
shape, but that doesn't reflect the reality of the underlying
work. Yes GDAL drivers are lying to do. All the time :-) ("<span><em>Traduttore,
traditore")</em></span> That's the whole purpose of GDAL.<span><em><br>
</em></span></p>
<p>If you try to compress too big blocks with libjxl (but here I'm
probably talking about > 10k x 10k pixels at once), you will
hit RAM issues at some point, because the libjxl compressor is
quite RAM hungry.<br>
</p>
<p>On the contrary when doing JPEGXL-in-TIFF with BLOCKYSIZE=1, you
really get one JPEGXL blob per line (that can be independently
decompressed). And you will kill any benefit from JPEGXL
compression since it is designed/optimized for 2D images, not
images degenerated to single lines. (contrary to ZLIB, ZSTD, LZMA
or LZW that are generic purpose methods totally ignoring the 2D
aspect)<br>
</p>
<p>Even</p>
<span style="white-space: pre-wrap">
</span>
<pre class="moz-signature" cols="72">--
<a class="moz-txt-link-freetext" href="http://www.spatialys.com">http://www.spatialys.com</a>
My software is free, but my time generally not.
Butcher of all kinds of standards, open or closed formats. At the end, this is just about bytes.</pre>
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