LIGHT_CORRECT(1)					      General Commands Manual						  LIGHT_CORRECT(1)

NAME

       light_correct - correct illumination errors on set of images

SYNOPSIS

       light_correct grey image1 image2 image3 ...

DESCRIPTION

       The  first  argument  should be an image of a piece of grey card, subsequent arguments should be images taken with the same lighting set-up
       which need correcting. The corrected images are written to files prefixed with "ic_".

       For example, suppose you have a directory with the following files in:

	 example% ls
	 dat1.1.v dat1.2.v dat2.1.v dat2.2.v dat3.1.v dat3.2.v
	 dat4.1.v dat4.2.v grey.v

       then run light_correct like this:

	 example% light_correct grey.v dat*.v

       to generate this:

	 example% ls
	 dat1.1.v dat1.2.v dat2.1.v dat2.2.v dat3.1.v dat3.2.v
	 dat4.1.v dat4.2.v grey.v
	 ic_dat1.1.v ic_dat1.2.v ic_dat2.1.v ic_dat2.2.v ic_dat3.1.v
	 ic_dat3.2.v ic_dat4.1.v ic_dat4.2.v

       light_correct works by smoothing out the grey card image, finding grey-mean/pixel for each point, and then multiplying the  result  by  all
       the following images. It also removes any .desc files it generates, to avoid problems with im_global_balance(3).

RETURN VALUE

       returns 0 on success and non-zero on error.

SEE ALSO

       header(1), vips(1)

COPYRIGHT

       The National Gallery and Birkbeck College, 1989-1996.

								    14 Oct 1996 						  LIGHT_CORRECT(1)