[ELGIS] POLL: 12 bit JPEG compression in TIFF [SEC=UNCLASSIFIED]

Peter Hopfgartner peter.hopfgartner at r3-gis.com
Mon Sep 5 05:21:09 EDT 2011


On 09/05/2011 12:51 AM, Bruce Bannerman wrote:
> Peter,
>
> Sorry to labour this point.
>
> It will depend on how the end user wants to use the data.
>
I could't agree more.
> If they want the data for analysis, via say an image processing 
> application, then anything that will degrade the data should be 
> discouraged. This includes compression via a lossy format such as JPEG 
> or ecw, MrSID, JPEG2000 etc. Analysts will typically want to work with 
> the numbers for each 'colour' band in the the imagery
>
What I am currently looking for is a reasonable format web mapping. So 
speed and relative quality are definitly important, size not that much 
(but uncompressed is too big).
> If the user is just after the data as a visualisation backdrop then 
> the JPEG compression should be fine.
>
>
> For an rpm package, if the TIFF -- JPEG compression is only available 
> as an option, then this should be fine.
>
> I wouldn't like to see it set up as the default option though.
>
> Bruce Bannerman
>
Peter
>
> On 2/09/11 11:23 PM, "Peter Hopfgartner" 
> <peter.hopfgartner at r3-gis.com> wrote:
>
>     In my current tests, image quality is fine. Anyway, when trying to
>     produce some maps from TIFF Orthophotos, with uncompressed GeoTiffs 10
>     maps took me 1.6 s, with JPEG-Compression the same maps were done only
>     after 53 s.
>
>     Peter
>
>     On 08/15/2011 11:35 AM, Micha Silver wrote:
>     > Hi Bruce:
>     >
>     > On Mon, 2011-08-15 at 09:53 +1000, Bruce Bannerman wrote:
>     >> Agreed.
>     >>
>     >> JPEG is a lossy compression format.
>     >>
>     > Yes, but when I tried the JPEG 12 bit compression, I found that pixel
>     > for pixel, it was almost exactly the same as the original tiff.
>     >
>     >
>     >> People who use tiff, typically want a lossless format.
>     >>
>     >> Therefore, I don't see the need for a JPEG compression of TIFF.
>     >>
>     >> If I wanted a lossy compression, I'd typically go for a wavelet
>     >> compression format like ecw.
>     > True, but I always get stuck with the restrictive licensing of ECW.
>     > And if jpeg 12bit gives a file size only double of the ECW
>     compression
>     > ratio, with *nearly* lossless results, it becomes interesting...
>     >
>     >> Bruce Bannerman
>     >>
>     >>
>     >> On 14/08/11 1:44 AM, "Peter Hopfgartner"
>     >> <peter.hopfgartner at r3-gis.com>  wrote:
>     >>
>     >>          --------Micha Silver<micha at arava.co.il>  wrote--------
>     >>
>     >>          Subject: Re: [ELGIS] POLL: 12 bit JPEG compression in TIFF
>     >>
>     >>          Date: 12.08.2011 12:12
>     >>
>     >>
>     >>
>     >> >On Fri, 2011-08-12 at 11:50 +0200, Mathieu Baudier wrote:
>     >>
>     >> >>  What about the compression rates of the standard TIFF
>     >>          compressions?
>     >>
>     >> >>  (Already available)
>     >>
>     >> >
>     >>
>     >> >AFAIK, regular TIFF compression (Packbits, or LZW and the
>     >>          like) only
>     >>
>     >> >give about 20% compression. JPEG is around 90-95%, ECW and
>     >>          MrSid even
>     >>
>     >> >more, and JPEG 12-bit looks to be about 85-90%.
>     >>
>     >> >
>     >>
>     >>          Most standard TIFF compression schemas are lossless
>     (similar
>     >>          to gzip compression in PNG). They might give great results
>     >>          when there are large areas with constant values. They
>     are not
>     >>          so performant for orthophotos, where, on the other
>     hand, some
>     >>          data loss might be acceptable.
>     >>
>     >>
>     >>
>     >>
>     >>
>     >> >>
>     >>
>     >> >>  On 12 Aug 2011 11:36, "Micha Silver"<micha at arava.co.il>
>     >>          wrote:
>     >>
>     >> >>
>     >>
>     >> >>
>     >>
>     >> >>
>     >>
>     >> >>  On 02/08/2011 12:01, Peter Hopfgartner wrote:
>     >>
>     >> >> >
>     >>
>     >> >> >  On 08/02/2011 09:01 AM, Mathieu Baudier wrote:
>     >>
>     >> >> >>...
>     >>
>     >> >>
>     >>
>     >> >>  Hi Peter:
>     >>
>     >> >>
>     >>
>     >> >>  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.
>     >>
>     >> >>
>     >>
>     >> >>  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").
>     >>
>     >> >>
>     >>
>     >> >>  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.
>     >>
>     >> >>
>     >>
>     >> >>  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.
>     >>
>     >> >>
>     >>
>     >> >>
>     >>
>     >> >>  Best, Micha
>     >>
>     >> >>
>     >>
>     >> >>
>     >>
>     >> >>
>     >>
>     >> >>
>     >>
>     >> >> > >  Peter
>     >>
>     >> >> > >  _______________________________________________
>     >>
>     >> >> > >  el mailing list
>     >>
>     >> >> > > el at lists.osgeo.org ...
>     >>
>     >> >> >
>     >>
>     >> >> >  This mail was received via Mail-SeCure System.
>     >>
>     >> >> >
>     >>
>     >>
>     >>
>     >>          Peter
>     >>
>     >>
>     >>
>     >>          R3 GIS Srl - GmbH
>     >>
>     >> http://www.r3-gis.com
>     >>
>     >>
>     >>
>     >>          _______________________________________________
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>     >>
>     >>
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