-interpolate NearestNeighbor behavior

[the7trumpets]

I am attempting to do 2d 2nd order polynomial warping of an image with a collection of control points.

I need the borders between two color regions to not be interpolated at all. If the source image goes from #00FF00 to #FF0000, then I want the warped image to also have that same transition (though at a different pixel location. I'm also using virtual-pixel Black to ensure that the edges of the warped image stay black.

Code: Select all

convert IN_FILE -virtual-pixel Black -interpolate NearestNeighbor -distort polynomial "2 $(cat control_points.txt)" OUT_FILE

However, the output of this shows interpolated boundaries with various colors between the two present in the source image at the border. I have also tried -interpolate Integer, and -filter Point, with the exact same effects I am seeing from the above command, where interpolated values are being added to the borders.


How do I apply a distortion without any interpolation, and retain 'hard' edges of the same color boundary in the source image?

[snibgo]

I think "-distort" uses "-filter", not "-interpolate". See http://www.imagemagick.org/script/comma ... hp#distort

Try "-filter box" or "-filter point".

[anthony]

As you guessed.. add "-filter point" then distort will use fast 'point interpolation' for color determination.
EG:
-filter point -interpolate nearest

Many examples of doing this is in IM examples distortion
http://www.imagemagick.org/Usage/distor ... nterpolate

[the7trumpets]

Thanks for the help. I have tried:

-filter Point
Same results as -interpolate NearestNeighbor

-filter Box
ALMOST what I'm looking for. There is only a single interpolated value instead of a smooth gradient along the borders.

[fmw42]

try -filter point -interpolate nearestneighbor

I believe that -filter point turns off EWA resampling and then allows -interpolate to work.

[the7trumpets]

try -filter point -interpolate nearestneighbor

I believe that -filter point turns off EWA resampling and then allows -interpolate to work.

That did it. Thanks a million!

FYI, that was not intuitive based on the documentation

[fmw42]

see
http://www.imagemagick.org/Usage/distorts/#lookup