Normalization:

The detected facial images can be cropped to obtain normalized images called canonical images. In a canonical face image, the size and position of the face are normalized approximately to the predefined values and the background region is minimized. Also, the image must be standardized in terms of size, pose, illumination, etc., relative to the images in the gallery or reference database. For this purpose, it is necessary to locate the facial landmarks accurately and failing to do so can make the whole recognition task unsuccessful. Recognition can only succeed if the probe image and the gallery images are the same in terms of pose orientation, rotation, scale, size, etc and normalization is meant to achieve this goal.