We highlight the need for – and describe initial strategies to find – new digital-optical basis functions and performance merit functions to serve as a foundation for designing, analyzing, characterizing, testing, and comparing a range of computational imaging systems. Such functions will provide a firm theoretical foundation for computational sensing and imaging and enhanced design software, thereby broadly speeding the development of computational imaging systems.

The charge-coupled devices used in electron microscopy are coated with a scintillating crystal that gives rise to a severe modulation transfer function (MTF). Exact knowledge of the MTF is imperative for a good correspondence between image simulation and experiment. We present a practical method to measure the MTF above the Nyquist frequency from the beam blocker's shadow image. The image processing has been fully automated and the program is made public. The method is successfully tested on three cameras with various beam blocker shapes.

We have experimentally investigated the MTF of a scientific grade CCD, especially considering its behavior induced by different laser wavelengths (from 470 nm to 633 nm) and varying number of total charge transfers. The MTF measurements were performed using laser speckles and utilizing the single-slit method. The MTF of the sensor was examined from zero to the Nyquist frequency. The results obtained at different wavelengths were compared. It was shown that the spectral behavior of the MTF is negligibly small; moreover the small variation is observed at the high frequency region. It was also observed that the variation of the total number of charge transfers, adjusted by size and location of the region of interest for readout pattern, is within the intrinsic error of the single-slit aperture laser speckle method.