I guess this is not that easy since you cannot say where your amorhous signal as increase of the background is comming from. However, in case you can, the next problem expects you already since SAED is dynamical diffraction theory and as far as I know there are numerous factors which can change the intensity, e.g. multiple scattering and diffraction. Even in case you coulve also this problem, the examination of the diffraction patterns will be only a rough estimation since the behaviour of your material (kinematic- dynamical) you can only estimate.