[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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> >
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