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.bonf...@gmail.com] > Lähetetty: 22. maaliskuuta 2012 11:26 > Vastaanottaja: Rahkonen Jukka > Kopio: mapserver-users@lists.osgeo.org > Aihe: Re: [mapserver-users] Image compression/performance > > On Thu, Mar 22, 2012 at 09:03, Rahkonen Jukka > <jukka.rahko...@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- > > _______________________________________________ > > mapserver-users mailing list > > mapserver-users@lists.osgeo.org > > http://lists.osgeo.org/mailman/listinfo/mapserver-users > _______________________________________________ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users