deltaEuv

 Compute delta E_uv from corresponding CIE XYZ values and a white point

    dEuv = deltaEuv(xyz1,xyz2,whitePnt)

 The white point can be a cell array with the white point for each of the
 two XYZ values, or it can be a single vector that applies to both of the
 XYZ data sets.

 ARGUMENTS
   xyz matrices are either XW  or RGB Image format.  
      If the data are XW format, then they a are (n*m, 3) matrices. 
      In RGB image format they are 3D arrays of n x m x 3.  
   whitePnt is the white point for the CIELAB calculation.  1x3 or 3x1 is OK.
 
 RETURNS
    dEuv is an array of delta E values. It has the same format as the
    input xyz (XW or RGB). 

 Example:

  whitePnt = imageGet(vci,'whitepoint');
  dataXYZ1 = imageDataXYZ(vci1,roiLocs);
  dataXYZ2 = imageDataXYZ(vci2,roiLocs);
  dEuv = deltaEuv(dataXYZ1,dataXYZ2,whitePnt)

 Copyright ImagEval Consultants, LLC, 2003.