Conditional Expressions for Blind Deconvolution: Derivative form
  We developed novel conditional expressions (CEs) for Lane and Bates' blind deconvolution. The CEs are given in term of the derivatives of the zero-values of the z-transform of given images. The CEs make it possible to automatically detect multiple blur convolved in the given images all at once without performing any analysis of the zero-sheets of the given images. We illustrate the multiple blur-detection by the CEs for a model image 
S. Aogaki, I. Moritani, T. Sugai, F. Takeutchi, and F.M. Toyama