THE RELATIONSHIP BETWEEN OBJECTIVE AND SUBJECTIVE IMAGE QUALITY CRITERIA

Sharpness characterized by AMT-acutance and graininess as subjective i mage 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 hardc opies from negative films is calculated by means of linear information theory using experimental data for the characteristic curves, modulat ion transfer functions and noise power spectra of all elements of the imaging chain, Conclusions about the optimum film exposure and the den sities most critical for the subjective evaluation of image quality ar e drawn from this analysis. Finally, the power-functional relationship s between objective and subjective image quality criteria based on SNR , and film sensitivity are quantified.