MTF and CTF measuring system for digital still cameras

An inexpensive measurement system for characterizing digital still cameras is described. The method adopted involves performing mathematical analyses directly on the images of test charts obtained from the DSC. These charts comprise of squarewave patterns with selected spatial frequencies, the phases of which with respect to the CCD sensors cover most or all of the phase domain. By working on the final images generated by DSCs, we can include the effects of the digital signal processing on the performance of the DSC. Slightly rotated optical patterns of squarewaves with different spatial frequencies were projected on the CCD to determine the phase-dependent CTF. These phase-dependent data were then statistically analyzed to obtain average CTF values that better describe the characteristics of the DSC. The low cost system developed in our laboratory is very suitable for evaluating and designing digital signal pro ces sing algorithms when developing digital still cameras.