Width in pixels of the filter extents. The filter will be applied to the
range of pixels within a box of +/- getSize() / 2 around
the center of the pixel.
Returns:
width in pixels
get
float get(float x,
float y)
Get value of the filter at offset (x, y). The filter should never be
called with values beyond its extents but should return 0 in those cases
anyway.