The current version allows for five different PSF models: The Gaussian model simulates a blurring effect by setting three different variance values. These values characterize the width of the PSF at various axial positions along the z-stack. The defocus model is simulated in the Fourier domain by a modulated Gaussian where the sinc modulation depends on the axial defocusing distance. Another defocusing model is due to Koehler, which also uses the Gaussian function in the Fourier domain. In this model, however, the sinc modulation is replaced by a linear term for the variance.