23 December 2002 Deconvolution in line scanners using a priori information
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Abstract
In a digital camera the MTF of the optical system must comprise a low-pass filter in order to avoid aliasing. The MTF of incoherent imaging usually and in principle is far from an ideal low-pass. Theoretically a digital ARMA-Filter can be used to compensate for this drawback. In praxis such deconvolution filters suffer from instability because of time-variant noise and space-variance of the MTF. In addition in a line scanner the MTF in scan direction slightly differs in each scanned image. Therefore inverse filtering will not operate satisfactory in an unknown environment. A new concept is presented which solves both problems using a-priori information about an object, e.g. that parts of it are known to be binary. This information is enough to achieve a stable space and time-variant ARMA-deconvolution filter. Best results are achieved using non linear filtering and pattern feedback. The new method was used to improve the bit-error-rate (BER) of a high-density matrix-code scanner by more than one order of magnitude. An audio scanner will be demonstrated, which reads 12 seconds of music in CD-quality from an audio coded image of 18mm×55mm size.
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Bernhard Wirnitzer, Tadeo Spraggon-Hernandez, "Deconvolution in line scanners using a priori information", Proc. SPIE 4792, Image Reconstruction from Incomplete Data II, (23 December 2002); doi: 10.1117/12.451790; https://doi.org/10.1117/12.451790
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