AN ASSESSMENT OF THE VARIATIONS IN IMAGE QUALITY WITH MULTIFORMAT CAMERAS

For CT and many other technology digital imaging methods, the final co py is often produced on a multiformat camera. The problems in imaging performance that arise in multiformat cameras are primarily due to dus t, dirt and other forms of soiling on the optical components, and to a drift in electronic components associated with the multiformat camera characteristics. This drift can be due to temperature variations and/ or deterioration in component performance over time within the format camera monitor. These problems, coupled with the fact that the system display monitor characteristics or video grey scale inversion may not be compensated for by the format camera, can lead to fluctuations in h ard copy density and can in turn lead to differences in brightness, co ntrast and signal-to-noise ratio in the resulting image. This study ex amines the hard copy and system display monitor fluctuations using a v ideo test pattern generator, a photodensitometer for film densities, a nd a photometer to measure light output from the display monitor. The hard copy fluctuations are measured for several grey-scale levels, and compared for four different film types. In this study the performance of multiformat cameras are compared; variations in performance have b een noted and may be attributed to camera age, choice of film, process ing and possibly film throughput. The conclusions of this work are rel evant to quality control and quality assurance procedures, and also to multiformat camera operation and usage.