### How to intuitively interpred Gabor lambda param?

I am playing with the newly added Gabor filters. I know some basics about them, and how they are used for recognition tasks. But I have troubles understanding in an intuitive way (not by writing complicated math formulas) what is the meaning of the lambda parameter.

Here is the formula, from Wiki:

And here are some pictures, where I varied lambda:

`lambda = CV_PI`

`lambda = CV_PI/2`

`lambda = CV_PI/4`

The other parameters are as follows:

```
gaborKernel = getGaborKernel( cv::Size(15, 15) , 3, -CV_PI/4, lambda, 1, CV_PI, CV_32F );
```