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<p class="MsoNormal">Hi,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-US">I made some tests about using JPEGXL (JXL) compression in GeoTIFF. I am interested in lossless compression. So far I have learned that stripes are not good, but results from tiled TIFFs are promising.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">The GeoTIFF driver manual has a warning about WEBP compression: “There is a significant time penalty for each tile/strip with lossless WebP compression, so you may want to increase the BLOCKYSIZE value for strip layout.”
I wonder if the same applies to JPEG XL compression as well. Without tiles this command was very slow<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">gdal_translate -of gtiff -co compress=jxl p4433h.tif p4433h_jxl.tif<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">This one was faster.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">gdal_translate -of gtiff -co tiled=yes -co compress=jxl p4433h.tif p4433h_jxl_tiled.tif<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Not only being slow but the compression with stripes does not really compress much. See the file sizes:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">With stripes: 359 211 087 p4433h_jxl.tif<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">With 256x256 tiles: 142 188 540 p4433h_jxl_tiled.tif<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Referense (LZW): 283 864 896 p4433h_lzw.tif<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">What might be the optimal block size for JXL-in-GeoTIFF when the aim is a good compression ratio and reasonable processing time?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">-Jukka Rahkonen-<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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