NAME
       im_dE_fromLab,  im_dECMC_fromLab,  im_dE00_fromLab  -  calculate colour
       differences
SYNOPSIS
       #include <vips/vips.h>
       int im_dE_fromLab(in1, in2, out)
       IMAGE *in1, *in2, *out;
       int im_dECMC_fromLab(in1, in2, out)
       IMAGE *in1, *in2, *out;
       int im_dE00_fromLab(in1, in2, out)
       IMAGE *in1, *in2, *out;
DESCRIPTION
       Given a pair of images in Lab format, these functions calculate  CIE76,
       CMC(1:1)  and  CIEDE2000 colour difference images.  These are the basic
       colour difference calculators  in  VIPS  ---  other  colour  difference
       functions,  such  as im_dE_fromXYZ(3), are provided as a convenience to
       the programmer.
       See im_Lab2XYZ(3) for an explanation of the various colour spaces  VIPS
       supports and how to convert between them.
RETURN VALUE
       The functions return 0 on success and -1 on error.
SEE ALSO
       im_col_XYZ2rgb(3), im_XYZ2rgb(3), im_dE_fromXYZ(3).
COPYRIGHT
       National Gallery, 1990 - 1993
AUTHOR
       J.Ph. Laurent - 2/12/1992
       J. Cupitt - 21/7/93
                                2 December 1992               im_dE_fromLab(3)