Opencv getGaborKernel parameters for filter bank

Question

How opencv getGaborKernel function parameters related to orientation and scale parameters?

I assume theta is orientation, but what refers to scale?

//! returns the Gabor kernel with the specified parameters CV_EXPORTS_W Mat getGaborKernel( Size ksize, double sigma, double theta, double lambd,double gamma, double psi=CV_PI*0.5, int ktype=CV_64F );

Here is example 5 scales and 8 orientations:

UPDATE:

Also I found this parameter explanation: http://matlabserver.cs.rug.nl/edgedetectionweb/web/edgedetection_params.html

Answer 1

Here are the meaning of parameters:

• ksize Size of the filter returned.
• sigma Standard deviation of the gaussian envelope.
• theta Orientation of the normal to the parallel stripes of a Gabor function.
• lambda Wavelength of the sinusoidal factor.
• gamma Spatial aspect ratio.
• psi Phase offset.
• ktype Type of filter coefficients. It can be CV_32F or CV_64F.

The orientation can be modified by theta and the scale by i.e. lambda. Here you have a good tutorial about What do the Gabor filter parameters mean?. Update September 2020: The link to What do the Gabor filter parameters mean? no longer works. Try Through The Eyes of Gabor Filter instead.

I also attach the image from the site above:

Copyright by Juergen Muller