USAGE: balance "shadows,midtones,highlights" [-b bias] infile outfile
USAGE: balance [-h or -help]

"shadows,midtones,highlights" .... percent change in values in shadows,
.................................. midtones, highlight areas in the image;
.................................. positive or negative floats
-b ........... bias .............. percent shift in midtone location;
.................................. positive or negative floats; default is
.................................. no change from mean of image.

PURPOSE: Enhances the shadows, midtones and highlight regions of the image.

DESCRIPTION: BALANCE enhances the shadows, midtones and highlight regions of the image. This is done according to a three point piece-wise linear transformation, where the three points are at input graylevels: 0, image mean, 255 (in 8-bit system). The transformation is applied as a look up table using -clut.

ARGUMENTS:

"shadows,midtones,highlights" ... Percent change in values in the shadows, midtones and highlight areas of the image. Values are positive or negative floats. A value of "0,0,0" means the output will be the same as the input.

-b bias ... BIAS is the percent shift of the midtone location from the mean value of the input. Values are positive or negative floats. The default=0 indicates no change from the global mean value of all channels of the input image.

REQUIREMENT: IM version 6.3.5-7 or higher due to the use of -clut.

CAVEAT: No guarantee that this script will work on all platforms, nor that trapping of inconsistent parameters is complete and foolproof. Use At Your Own Risk.