Adaptive filter
AssigneeTelefonaktiebolaget L M Ericsson (publ)
InventorsKenneth Andersson, Andreas Rossholm
Life of this patent
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Abstract
An adaptive filter that, in one embodiment, filters rows of pixels of an image in a vertical direction, stores the results in row vectors, and then filters the row vectors in the horizontal direction, and displays the results or stores the results for later display. Coefficients of a reference filter are modified based on the output from the reference filter through a table-lookup process that accesses tables of modified filter coefficients. The output of the modified filter is added to a delayed version of the input to provide the adaptive filter output.
Claims52
An apparatus for adaptively filtering an input stream of data values, comprising:
- a delay element that receives the input stream and generates a delayed stream;
- a filter having coefficients that determine a filter function, wherein the filter receives the input stream and generates a filtered stream according to the filter function;
- a combiner that receives the delayed stream and the filtered stream and generates an output stream of filtered data values;
- a weight generator, in communication with the filter, that generates weight coefficients that selectively modify the coefficients of the filter, wherein the weight generator includes:
- an address generator that generates addresses based on the filtered stream;
- and
- at least one table of modifying weight coefficients, wherein addresses produced by the address generator correspond to respective sets of modifying weight coefficients, and the sets of modifying weight coefficients are arranged in a predetermined relationship with the addresses;
- wherein the coefficients of the filter are modified by sets of modifying weight coefficients corresponding to addresses such that the apparatus adaptively filters the input stream of data values.
A method of adaptively filtering an input group of values, comprising the steps of:
- delaying the input group;
- filtering the input group according to a reference filter function determined by a set of filter coefficients, thereby generating a filtered input group of values;
- combining the delayed input group and the filtered group, thereby producing an output group of values;
- generating weight coefficients based on the filtered input group;
- modifying the set of filter coefficients according to the generated weight values;
- and
- filtering the input group according to a modified reference filter function determined by the modified set of filter coefficients;
- wherein the step of generating weight coefficients includes:
- generating an address based on the filtered input group;
- and
- retrieving, from at least one table, the weight coefficients;
- and
- the address corresponds to a respective set of weight coefficients;
- sets of weight coefficients are arranged in a predetermined relationship with the addresses;
- and the set of filter coefficients is modified by the retrieved set of weight coefficients.
A computer-readable medium containing a computer program for adaptively filtering an input group of values, wherein the computer program performs the steps of:
- delaying the input group;
- filtering the input group according to a reference filter function determined by a set of filter coefficients, thereby generating a filtered input group of values;
- combining the delayed input group and the filtered group, thereby producing an output group of values;
- generating weight coefficients based on the filtered input group;
- modifying the set of filter coefficients according to the generated weight values;
- and
- filtering the input group according to a modified reference filter function determined by the modified set of filter coefficients;
- wherein the step of generating weight coefficients includes:
- generating an address based on the filtered input group;
- and
- retrieving, from at least one table, the weight coefficients;
- and
- the address corresponds to a respective set of weight coefficients;
- sets of weight coefficients are arranged in a predetermined relationship with the addresses;
- and the set of filter coefficients is modified by the retrieved set of weight coefficients.
Dependencies are inferred from the claim text.