AN AUTOMATIC METHOD TO DETERMINE CUTOFF FREQUENCY BASED ON IMAGE POWER SPECTRUM

We present an algorithm for automatically choosing filter cutoff frequ ency (F-c) using the power spectrum of the projections. The method is based on the assumption that the expectation of the image power spectr um is the sum of the expectation of the blurred object power spectrum (dominant at low. frequencies) plus a constant value due to Poisson no ise. BS' considering the discrete components of the noise-dominated hi gh-frequency spectrum as a Gaussian distribution N(mu, sigma), the Stu dent t-test determines F-c as the highest frequency for which the imag e frequency components are unlikely to be drawn from N(mu, sigma). The method is general and can be applied to any filter, In this work, we tested the approach using the Metz restoration filter on simulated, ph antom, and patient data vith good results, Quantitative performance of the technique was evaluated bq plotting recovery coefficient (RC) ver sus NMSE of reconstructed images.