abs_invar_fourier_coeffT_abs_invar_fourier_coeffAbsInvarFourierCoeffabs_invar_fourier_coeffAbsInvarFourierCoeffAbsInvarFourierCoeff (Operator)

Name

abs_invar_fourier_coeffT_abs_invar_fourier_coeffAbsInvarFourierCoeffabs_invar_fourier_coeffAbsInvarFourierCoeffAbsInvarFourierCoeff — Normalizing of the Fourier coefficients with respect to the displacment of the starting point.

Warning

abs_invar_fourier_coeffabs_invar_fourier_coeffAbsInvarFourierCoeffabs_invar_fourier_coeffAbsInvarFourierCoeffAbsInvarFourierCoeff is obsolete and is only provided for reasons of backward compatibility.

Signature

Description

The operator abs_invar_fourier_coeffabs_invar_fourier_coeffAbsInvarFourierCoeffabs_invar_fourier_coeffAbsInvarFourierCoeffAbsInvarFourierCoeff normalizes the Fourier coefficients with regard to the displacements of the starting point. These occur when an object is rotated. The contour tracer get_region_contourget_region_contourGetRegionContourget_region_contourGetRegionContourGetRegionContour starts with recording the contour in the upper lefthand corner of the region and follows the contour clockwise. If the object is rotated, the starting value for the contour point chain is different which leads to a phase shift in the frequency space. The following two kinds of normalizing are available:

abs_amount:

The phase information will be eliminated; the normalizing does not retain the structure, i.e. if the AZ-invariants are backtransformed, no similarity with the pattern can be recognized anymore.

az_invar1:

AZ-invariants of the 1st order execute the normalizing with respect to displacing the starting point so that the structure is retained; they are however more prone to local and global disturbances, in particular to projective distortions.

For the input Fourier coefficients (RealInvarRealInvarRealInvarRealInvarRealInvarrealInvar, ImaginaryInvarImaginaryInvarImaginaryInvarImaginaryInvarImaginaryInvarimaginaryInvar) only odd numbers of parameter values are allowed.

Parallelization

• Multithreading type: reentrant (runs in parallel with non-exclusive operators).
• Multithreading scope: global (may be called from any thread).
• Processed without parallelization.

Parameters

Example (C++ (HALCON 5.0-10.0))

get_region_contour(single,&row,&col);
length_of_contour = length_tuple(row);
move_contour_orig(row,col,&trow,&tcol);
prep_contour_fourier(trow,tcol,"unsigned_area",&param_scale);
fourier_1dim(trow,tcol,param_scale,50,&frow,&fcol);
invar_fourier_coeff(frow,fcol,1,"affine_invar",&invrow,&invcol);
abs_invar_fourier_coeff(invrow,invcol,1,2,"az_invar1",&absrow,&abscol);
fourier_1dim_inv(absrow,abscol,length_of_contour,&fsynrow,&fsyncol);

Module

Foundation