[gdal-dev] Re: gdalwarp -of JPEG

[Frank Warmerdam]

Jukka Rahkonen wrote:
> Craig Leat <craig.leat <at> gmail.com> writes:
> 
>> Hi,
>>
>> I have noted with gdal 1.6.1 that gdalwarp -of JPEG returns the error
>> message "Output driver `JPEG' not recognised or does not support
>> direct output file creation." However, gdal_translate -of JPEG works.
>> Is there any justifiable reason that gdalwarp does not support writing
>> JPEG or is wrapping JPEG inside GTiff the usually way of doing things?
>>
>> Thanks for any insights,
> 
> Hi,
> 
> I believe that in warping process data needs to be written in arbitrary places
> into the output image and that can be impossible or ineffective if the target
> image is jpeg compressed.  I guess it might be done somehow when simply warping
> one whole image to another projection as it is, but gdalwarp can do other nice
> things like warping from virtual mosaic or warp new data into an existing output
> image. Let gdalwarp create an uncompressed tiff first and compress it to jpeg
> afterwards. I bet it is also the fastest way do get the job done.

Craig,

Jukka is correct.  There is a bit more information on this in the FAQ:

http://trac.osgeo.org/gdal/wiki/FAQRaster#Whywontgdalwarporgdal_mergewritetomostformats

Best regards,
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