| 摘要 |
PURPOSE:To improve the response characteristic by providing a control means decreasing the pass band width of an FIR filter in response to the degree of compression in comparison with non-compression, combining plural intermediate words and causing an output word representing the filtering over a large region being an integer multiple of a prescribed region of a picture. CONSTITUTION:The control means 60 decreases the band width of a 2D-FIR filter in response to the compression rate in each direction in comparison with each band width at no compression. Thus, as the compression rate is increased, the filter band width is reduced, the 2D spectrum of a signal from the filter reaches the Nyquist limit frequency, the aliasing by compression is avoided or at least reduced. Further, the control means 60 combined plural intermediate words formed by the filter and whose plural sizes related to the compression rate periodically and produces an output word representing the filtering over a picture region being an integral number of multiple of a prescribed region corresponding to mXn sample array formed by an array memory 26. Thus, the response characteristic close to the ideal response is obtained.
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