Thk u for your detail reply. 1.Now,I have a DEM(.img) file,and its band number is 1.When I use 'gdal_translate -b 1 -of PNG old.img new.png' to create a png file(I think its contains height map infomation,is it?).the error 'Warning 6:PNG driver doesn't support data type Int16.Only eight bit<Byte>' and sixteen bit<Uint16> bands supported.Defaulting to Byte. 2.When I use 'gdal_translate -b 1 -of JPEG old.img new.jpg',the error 'JPEG doesn't support data type Int16. Only eight and twelve bit bands supported<Mk1 libjepg>' happy every day.
>weixj2003ld wrote: >> Thk u very much. >> I have two questions. >> 1.If I want to use the following combination, >> Red=Band3 >> Green=Band2*0.8+band4*0.2; >> Blue=band1 > >Wei, > >This will require programming or scripting. It cannot be done >with the stock commandline tools. > >> 2. what is the general combination for good look jpeg file? > >That depends greatly on the source sensor and the goals of the visualization. >A 4,2,1 b false color band combination is common with Landsat imagery, >butit can be disputed whether it looks good or not. Also, constrast >stretching is often also desirable on satellite imagery for best >visualization. > >Best regards, > >-- >---------------------------------------+-------------------------------------- >I set the clouds in motion - turn up | Frank Warmerdam, [email protected] >light and sound - activate the windows | http://pobox.com/~warmerdam >and watch the world go round - Rush | Geospatial Programmer for Rent >
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