There are many tricks we can play to obtain more training data, such as using mirrored faces, adding random noise, shifting the face by a few pixels, scaling the face by a percentage, or rotating the face by a few degrees (even though we specifically tried to remove these effects when preprocessing the face!) Let's add mirrored faces to the training set, so that we have both, a larger training set as well as a reduction in the problems of asymmetrical faces or if a user is always oriented slightly to the left or right during training but not testing. This is done as follows: