Thanks Even<div><br></div><div>However if I do the same thing with reprojection I get the same result. gdalwarp output looks sharp and ugly, imagemagick output looks nice.</div><div><br></div><div>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.</div>
<div><br></div><div>Regards</div><div>Craig de Stigter<br><br><div class="gmail_quote">On Thu, Sep 30, 2010 at 10:34 AM, Even Rouault <span dir="ltr"><<a href="mailto:even.rouault@mines-paris.org">even.rouault@mines-paris.org</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">Craig,<br>
<br>
The main reason is that you are using gdalwarp to reduce an image by a large<br>
factor and not reproject it, which generally only involves image resizing by<br>
small factors. The implementation of the bilinear and cubic resampling<br>
algorithms is currently not designed for the pure resizing use case and takes<br>
only into account a few source pixels (basically if to compute a destination<br>
pixel you would need to take into account a 5x5 source window, they will only<br>
used the 4 corners of that square, which fine usually since those are just the<br>
immediate neighbours of the source pixel), whereas cubicspline and lancsoz<br>
take into account more pixels (all the pixels in the 5x5 square).<br>
<br>
Best regards,<br>
<br>
Even<br>
<br>
Le mercredi 29 septembre 2010 22:27:01, Craig de Stigter a écrit :<br>
> Hi folks<br>
><br>
> I filed this bug <<a href="http://trac.osgeo.org/gdal/ticket/3740" target="_blank">http://trac.osgeo.org/gdal/ticket/3740</a>> on gdal a few<br>
<div><div></div><div class="h5">> weeks back and haven't heard anything since.<br>
><br>
> Would someone mind taking a look at it?<br>
><br>
> Thanks<br>
> Craig de Stigter<br>
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