preproc params.

Preprocessing of the source images to enhance edge information is performed as well as edge detection. The enhancement technique used is determined by the enhance choice selection and the parameters set up by the Cor params dialogue box. Enhancement can be any of:

Dx gauss. Horizontal first differences followed by horizontal gaussian
          smoothing with distribution width = sigma1.

Dx.       Horizontal first differences.

DoG.      Difference of gaussians filtering with  DoG = k1 x G_sigma 1
                                                  + k2  G_sigma 2.
grad      Summed squares of vertical and horizontal derivatives (needed for complete 3D data extraction).

None.     No preprocessing.

The DoG parameters are used by preproc.

The edge detection is performed automatically and the number of edge pixels within the block is used (in the absense of an input disparity image) to determine whether a block contains enough information to attempt correlation.