[mapserver-users] Image compression/performance

[Rahkonen Jukka]

Hi,

Sure, I should have written the most suitable ready-to-use commands and not just put a mention later in the text where nobody reads it :)
 "and JPEG compressed tiffs without tiles will for sure be a fiasco."

-Jukka-

> -----Alkuperäinen viesti-----
> Lähettäjä: thomas bonfort [mailto:thomas.bonfort at gmail.com] 
> Lähetetty: 22. maaliskuuta 2012 11:26
> Vastaanottaja: Rahkonen Jukka
> Kopio: mapserver-users at lists.osgeo.org
> Aihe: Re: [mapserver-users] Image compression/performance
> 
> On Thu, Mar 22, 2012 at 09:03, Rahkonen Jukka 
> <Jukka.Rahkonen at mmmtike.fi> wrote:
> > Stephen Woodbridge wrote:
> >
> >> On 3/21/2012 11:18 PM, Ian Walberg wrote:
> >> > Folks,
> >> >
> >> > We are using tif format images and getting good map rendering
> >> > performance.
> >> >
> >> > However the image file size could do with reducing a little.
> >> >
> >> > Anyone got experience of what compression options we have
> >> that have the
> >> > least impact on performance?
> >>
> >> My experience of working with USGS DOQQ satellite imagery 
> in GeoTiff
> >> files, was that the amount of compression really did not make a
> >> significant reduction in size. We used internally tiled tiff
> >> files with
> >> overviews and had over 15TB of imagery online. There are
> >> other formats
> >> that provide higher compression rates like MrSID and others, but
> >> depending on the format the behavior characteristics vary
> >> greatly and I
> >> do not have any recent stats or comparisons of size versus
> >> performance
> >> versus format.
> >
> >
> > Hi,
> >
> > I took numbers from one of our orthoimage set
> >
> > Uncompressed tiff files from the contractor
> >  667 File(s) 289 260 585 944 bytes
> >
> > What we have on server disk after running
> > gdal_translate -co COMPRESS=JPEG -co PHOTOMETRIC=YCBCR
> >  667 File(s) 21 411 672 702 bytes
> 
> I suspect you'll get superior access performance if you add -co
> TILED=yes to that command (and to your gdaladdo overview creation
> also).
> From my experience, tiled tiffs with jpeg compression and overviews
> was by far the best compromise between disk usage and access
> performance, provided the jpeg destructive compression isn't a
> showstopper for your particular application.
> 
> --
> thomas
> 
> 
> >
> > Reduction in size 93%.  Aerial images are used for 
> on-screen interpretation and difference in quality is not 
> visible with bare eyes. The rate of the JPEG compression can 
> be adjusted but I have been happy with GDAL defaults. 
> Overviews seem to add about 40-50% to JPEG compressed images. 
> Those I have created probably as
> > gdaladdo -ro --config COMPRESS_OVERVIEW JPEG --config 
> PHOTOMETRIC_OVERVIEW YCBCR
> >         --config INTERLEAVE_OVERVIEW PIXEL tiff.tif 2 4 8 16 32 64
> >
> > We have also JPEG2000 versions of the images but GDAL does 
> not handle them as fast as JPEG-in-TIFF files. A few years 
> ago the speed with JPEG2000 (with EWCJP2 and KAKJP2 drivers) 
> was about the half of what we got with tiffs. Those numbers 
> are nothing to rely on today because the software versions 
> have changed so many times.  Because of the unfriendly 
> licenses of the good JPEG2000 libraries and because 
> jpeg-in-tiff works so well I have not bothered to repeat the 
> tests myself lately. Generally, for this kind of questions 
> the best answer is achieved by making a well controlled test 
> in your own environment. You can then publish your results 
> and tell how you did the test so that others can check if 
> something has been were poorly configured. For example it is 
> not at all the same how JPEG2000 images have been compressed 
> and JPEG compressed tiffs without tiles will for sure be a fiasco.
> >
> > -Jukka Rahkonen-
> >  _______________________________________________
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>