This paper describes an approach to estimate the parame- ters of a motion blur (direction and length) directly form the observed image. The motion blur estimate can then be used in a standard non- blind deconvolution algorithm, thus yielding a blind motion deblurring scheme. The estimation criterion is based on recent results about the general spectral behavior of natural images. Experimental results show that the proposed approach is able to accurately estimate both the length and orientation of motion blur kernels, even for small lengths which are traditionally di-cult.