SYNOPSIS
exrnlm input.exr blur.exr output.exr
DESCRIPTION
Performs the non-linear masking function described in this paper:
N. Moroney. Local Color Correction Using Non-Linear Masking. IS&T 8th Color Imaging Conference, 108-111 (2000).
The input image should be normalized, and the whitepoint image should be at the same scale factor as the input image.