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<p style="padding:0;margin:0"><span style="font-size: 12px;"><span style="font-family: verdana,geneva,sans-serif;">I'll start next week some tests on this topic. I would like to include epsilon for wavelet compression. This might get similar results as ECW.</span></span></p>
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<p style="padding:0;margin:0"><span style="font-size: 12px;"><span style="font-family: verdana,geneva,sans-serif;">Peter</span></span></p>
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<p style="padding:0;margin:0"><span style="font-size: 12px;"><span style="font-family: verdana,geneva,sans-serif;">--------Micha Silver <micha@arava.co.il> wrote--------</span></span></p>
<p style="padding:0;margin:0"><span style="font-size: 12px;"><span style="font-family: verdana,geneva,sans-serif;">Subject: Re: [ELGIS] POLL: 12 bit JPEG compression in TIFF</span></span></p>
<p style="padding:0;margin:0"><span style="font-size: 12px;"><span style="font-family: verdana,geneva,sans-serif;">Date: 12.08.2011 12:07</span></span></p>
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<blockquote style="border-left: 2px solid #00F; margin: 0 0 0 10px; padding: 0 0 0 5px;">
<p style="margin-bottom: 0cm; margin-top: 0pt;">On 02/08/2011 12:01, Peter Hopfgartner wrote:</p>
<blockquote cite="mid:4E37BCE5.3070000@r3-gis.com">On 08/02/2011 09:01 AM, Mathieu Baudier wrote:<br />
<blockquote>
<blockquote>I do not know of any direct drawback, except that internal libjpeg and<br />
libtiff/libgeotiff are used, instead of the system shared libs.<br /></blockquote>
Frank Warmerdam advised against using the internal libtiff back in October 2010:<br />
<a class="moz-txt-link-freetext" href="http://lists.osgeo.org/pipermail/el/2010-October/000119.html">http://lists.osgeo.org/pipermail/el/2010-October/000119.html</a><br />
(the same would probably apply for libjpeg I guess)<br /></blockquote>
We could think about a separate gdal, e.g. gdal-il, package with internal libs, with bigTIFF and 12 bit enabled. BTW, UbuntuGIS is using internal libs, too.<br /></blockquote>
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<p style="margin-bottom: 0cm; margin-top: 0pt;">Hi Peter:</p>
<p style="margin-bottom: 0cm; margin-top: 0pt;">I did a quick (amateur) test of jpeg 12 this morning and I must say I was surprised with the results. I started with a 1.4 GB tiff ortho photo, which I also have as an ECW image. The ECW is about 64MB.</p>
<p style="margin-bottom: 0cm; margin-top: 0pt;">I used the OSGeo4W installation of gdal with the libjpeg that supports 12 bit, and I made two compressed tiffs. The regular jpeg compression came down to about 75 MB, a bit larger than the ECW, but it's quality was a bit fuzzy with color changes in the pixels. (Of course ECW is also lossy, introducing changes in the pixel coloring, but keeping "sharpness").</p>
<p style="margin-bottom: 0cm; margin-top: 0pt;">The 12 bit jpeg-compressed tiff came down to about 120 MB, only twice the size of the ECW, but it was almost indistinguishable from the original tiff! Both in coloring and sharpness. That was very impressive, I must say.</p>
<p style="margin-bottom: 0cm; margin-top: 0pt;">I don't know where the jpeg2000 format is going (if anwhere). For now this 12-bit jpeg compression looks like an ideal alternative to struggling with the closed ECW format on one hand, or the unwieldy file sizes of uncompressed tiff on the other.</p>
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<p style="margin-bottom: 0cm; margin-top: 0pt;">Best, Micha</p>
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<blockquote cite="mid:4E37BCE5.3070000@r3-gis.com">Peter<br />
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