normpat - normalize RADIANCE pictures for use as patterns.
normpat [ -v ][ -b ][ -f ][ -r maxres ] picture ..
Normpat normalizes one or more RADIANCE pictures to an average brightness of 1.0 and optionally removes fundamental frequencies and blends the edges of the image. The original images are overwritten during this process, and it is recommended that the program work on copies of the pictures for this reason.
The -r option can be used to set the maximum horizontal or vertical resolution of the final result, which should not be greater than 256 for most patterns (due to the associated memory burden during rendering). The -f option uses a Fourier transform to remove the lowest frequencies from the image, reducing the noticeability of pattern repitition. The -b option can be used to blend the edges of the image so that when it is tiled, the seams are less apparent. The -v option turns on the verbose flag, which prints on the standard output progress messages as the script runs.
Normpat is a shell script that makes calls to other RADIANCE programs that do the actual work.
getinfo(1), pcomb(1), pcompos(1), pfilt(1), pflip(1), protate(1), psign(1), ra_bn(1), ra_pr(1), ra_t8(1), ra_t16(1), rpict(1)