Issue:

I've got an issue with adding a face image to a user when I have set only the faceImage parameter.

Cause:

Every face image needs to be loaded with its face size. Parameters minFaceSize and maxFaceSize are used to define the minimal and maximal expected face size. If you use only the addFace(final byte[] faceImage) method, the default values for the face size parameter will be used (minFaceSize = 40, maxFaceSize = 200). 

Solution:

Probably, the face image you are trying to add to a user is not as big as the defaults are set. You need to add more parameters to the addFace() function. That means, use addFace(final byte[] faceImage, final int minFaceSize, final int maxFaceSize) function and provide the right