20 October 2004 The general image quality equation and the structure of the modulation transfer function
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Previous work by Hindsley and Mozurkewich (2001) showed that analysis of the Modulation Transfer Function (MTF) demonstrated the proportionality of signal-to-noise in a sparse aperture to the fill factor of the aperture. Analysis of the MTR also could enumerate the noise amplification characteristics of particular sparse apertures. However, such image quality metrics as the General Image Quality Equation (GIQE) also include edge effects, basically due to ringing and reduction in the edge sharpness. Here we report on our analysis of the MTF in order to quantify the relationship between the other terms in the GIQE and the structure of the MTF. We find that, for a fixed amount of optical surface, the image quality will improve with decreasing fill fraction due to an increase in resolution. Apodization of the Wiener Filter used to restore the image, as advocated by Hindsley and Mozurkewich, does not result in an improved image quality; use of the traditional unapodized Wiener Filter is highly favored. While the GIQE does not appear very sensitive to input signal-to-noise ratio (SNR), the input SNR does limit the ability to successfully reconstruct the image and is the ultimate limiting constraint on the fill fraction.
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Robert B. Hindsley, Robert B. Hindsley, Lee J. Rickard, Lee J. Rickard, } "The general image quality equation and the structure of the modulation transfer function", Proc. SPIE 5491, New Frontiers in Stellar Interferometry, (20 October 2004); doi: 10.1117/12.552341; https://doi.org/10.1117/12.552341


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