Tell me more ×  I'm using gdal to warp images into a different
map-projections. However the warping processs seem to leave grey
marks where the boundary of the original image was (see
warped.png below). I figured out this was probably caused by my
image having a white background and the 'filler' pixels created
by the warping process being transparent but black. And the
interpolation is smudging the black and white together (even
though it shouldnt as the black is transparent).  Is there any
way to avoid the grey outline from appearing? Maybe force
gdalwarp to fill with opaque white rather than transparent
black?  I cant do a square crop on the warped image as I'll
loose bits of the image, and I cant just make my background
black instead of white as this messes up some filtering I have
to do beforehand.  Theres seems to be lots of options for
gdalwarp that sound useful like -srcnodata but I cant figure out
how to use them. Thanks     share|improve this question add
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