Operators |
fourier_1dim — Calculate the Fourier coefficients of a parameterized contour.
fourier_1dim is obsolete and is only provided for reasons of backward compatibility.
fourier_1dim( : : Rows, Columns, ParContour, MaxCoef : RealCoef, ImaginaryCoef)
The operator fourier_1dim calculates the Fourier coefficients of a parameterized contour by using a valid parameter scale. This parameter scale may, for instance, be created with the help of the operator prep_contour_fourier. This function serves to calculate the Fourier coefficients of closed contours which are treated like complex-valued curves. Therefore, in order to determine the Fourier coefficients, the Fourier transform for periodical functions is used. Hereby the parameter MaxCoef determines the absolute value + 1 of the maximal number of Fourier coefficients, i.e. if n coefficients are indicated, the operator will calculate coefficients ranging from -n to n. The contour will be approximated without loss, if n = number of the contour points, whereby n = 100 approximates the contour so well that an error can hardly be distinguished; n in [40,50] however is sufficient for most applications. If the parameter MaxCoef is set to 0, all coefficients will be determined.
Row coordinates of the contour.
Column coordinates of the contour.
Parameter scale.
Desired number of Fourier coefficients or all of them (0).
Default value: 50
Suggested values: 0, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 400
Restriction: MaxCoef >= 0
Real parts of the Fourier coefficients.
Imaginary parts of the Fourier coefficients.
get_region_contour(single,&row,&col); move_contour_orig(row,col,&trow,&tcol); prep_contour_fourier(trow,tcol,"unsigned_area",¶m_scale); fourier_1dim(trow,tcol,param_scale,&frow,&fcol); invar_fourier_coeff(frow,fcol,1,"affine_invar",&invrow,&invcol); abs_invar_fourier_coeff(invrow,invcol,1,2,"az_invar1",&absrow,&abscol);
Foundation
Operators |