Selon Jukka Rahkonen <[email protected]>: > Hi, > > I would like to know what happens if I convert an original RGBA tiff image > into jpeg as > > gdal_translate -of jpeg rgba_in.tif jpeg_out.jpg > > I know that for getting a good result I can add "-b 1 -b 2 -b 3" but I am > curious to know what happens and how GDAL computes sort of a transparent > sepia coloured mask when run without selecting bands.
It will result in a TIFF with separate bands (PLANARCONFIG_SEPARATE : http://www.awaresystems.be/imaging/tiff/tifftags/planarconfiguration.html), each of them JPEG compressed. So for a transparency mask with "instantenous" changes between zones of fully transparence and fully opacity, you'll have JPEG artifacts. I'm wondering if the "sepia coloured mask" is not caused by a viewer that will be confused by this TIFF configuration and would assume a CMYK color space instead of RGB. > > -Jukka Rahkonen- > > _______________________________________________ > gdal-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/gdal-dev > _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
