| 摘要 |
<p>A 2D-FIR filter arrangement comprises a 2D-FIR filter (26,30,32,34) operative during each of a plurality of successive clock periods equal to T (where T is the spacing of digital samples or words of an image signal) to effect filtration over a predetermined area of the image by processing n x m words of the signal, having a predetermined spatial relationship in the form of an array, to produce an intermediate word. Some of the intermediate words are stored in a partial products store (28). Control means (60) is responsive to a signal (HCF,VCF) indicating an extent to which the image is to be compressed to do two things. Firstly, it causes the FIR filter (26,30,32,34) to adopt a bandwidth which is reduced, with respect to a value for zero compression, by an extent related to the extent of compression. This reduces or prevents aliasing that otherwise would be caused by the compression operation. Secondly, it causes a plurality of the intermediate words, the size of which plurality is related to the extent of compression, to be combined (48) to produce output words (56) representation of filtration over an area of the image which is a multiple of the above-mentioned predetermined area, improving the response of the filter arrangement. </p> |
