N1,N2 are the dimensions of the image. Units are pixels. N1,N2 are the dimensions of the image. Units are pixels. A counter-clockwise rotation of the y axis to the ellipse major axis is a positive angle.
Units are degrees.
If N1,N2 are the dimensions of the image. Units are pixels. Threshold of the band of second derivatives searched by the zero crossing algorithm. A reasonable value may be determined by inspection or statistical analysis of the second derivative image. A nominal value for 16-bit intensity images might be 1000.