THE RELATIONSHIP BETWEEN OBJECTIVE AND SUBJECTIVE IMAGE QUALITY CRITERIA

Sharpness characterized by AMT-acutance and graininess as subjective image quality criteria are compared with other subjective image quality criteria derived from the signal-to-noise ratio (SNR) of photographic films and hardcopies on photographic paper. The SNR of enlarged hardcopies from negative films is calculated by means of linear information theory using experimental data for the characteristic curves, modulation transfer functions and noise power spectra of all elements of the imaging chain, Conclusions about the optimum film exposure and the densities most critical for the subjective evaluation of image quality are drawn from this analysis. Finally, the power-functional relationships between objective and subjective image quality criteria based on SNR, and film sensitivity are quantified.