The only way to 'force' it is to use cubicspline or lanczos. Everything else has a hardcoded filter size. If those are too slow, I'd suggest using the OpenCL code I wrote over the summer. It's many times faster. (It should be in trunk soon if it isn't already.)
http://github.com/mailseth/OpenCL-integration-for-GRASS---GDAL ~Seth On Wed, September 29, 2010 4:12 pm, Craig de Stigter wrote: > Thanks Even > > However if I do the same thing with reprojection I get the same result. > gdalwarp output looks sharp and ugly, imagemagick output looks nice. > > Is there any way to force the bilinear/cubic interpolation to notice more > pixels? The other interpolation methods are much slower, I imagine even > forcing cubic to notice all of the 5x5 pixels would still be faster. > > Regards > Craig de Stigter > > On Thu, Sep 30, 2010 at 10:34 AM, Even Rouault > <even.roua...@mines-paris.org >> wrote: > >> Craig, >> >> The main reason is that you are using gdalwarp to reduce an image by a >> large >> factor and not reproject it, which generally only involves image >> resizing >> by >> small factors. The implementation of the bilinear and cubic resampling >> algorithms is currently not designed for the pure resizing use case and >> takes >> only into account a few source pixels (basically if to compute a >> destination >> pixel you would need to take into account a 5x5 source window, they will >> only >> used the 4 corners of that square, which fine usually since those are >> just >> the >> immediate neighbours of the source pixel), whereas cubicspline and >> lancsoz >> take into account more pixels (all the pixels in the 5x5 square). >> >> Best regards, >> >> Even >> >> Le mercredi 29 septembre 2010 22:27:01, Craig de Stigter a écrit : >> > Hi folks >> > >> > I filed this bug <http://trac.osgeo.org/gdal/ticket/3740> on gdal a >> few >> > weeks back and haven't heard anything since. >> > >> > Would someone mind taking a look at it? >> > >> > Thanks >> > Craig de Stigter >> > > > > -- > Koordinates Ltd > PO Box 1604, Shortland St, Auckland, New Zealand > Phone +64-9-966 0433 Fax +64-9-969 0045 > Web http://www.koordinates.com > _______________________________________________ > gdal-dev mailing list > gdal-dev@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/gdal-dev _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
