When should we use the full Gabor Function and when do we use only the real part? In this YouTube video, we see that the guy is only using the real part of the Gabor Filter to implement his project.

My questions are,


When should we use the complex Gabor Function?
When should we use the real part of the Gabor Function?
When should we use the imaginary part of the Gabor Function? Or, do we ever need it?
The real part of the complex Gabor function is symmetric. This means it will give a large response at the centre of symmetric features such as lines. 

The imaginary part of the complex Gabor function is anti-symmetric. This means it will give a large response at the centre of anti-symmetric features such as edges.

The real and imaginary parts are sort of in quadrature. This means when you take the magnitude of the response to the complex Gabor filter it will be high at the location of both edge and line features, which can be useful.