Dual-mode image interpolation filter operable in a first mode for storing interpolation coefficients and in a second mode for effecting television standards conversion at a pixel rate

摘要

An interpolation filter is used in television standards conversion to decimate an input sequence of higher definition signals into an output sequence of lower definition signals. The filter is partitioned into a plurality of computational stages. Within each stage, the decimation coefficients are stored in a random access coefficient memory and applied to a multiplier to generate the product of a digital input signal and a stored coefficient. The RAM is operable in two modes: a first mode in which new sets of coefficients are serially input to the RAM during the field blanking period and a second mode in which different stored coefficients are output to the multiplier for consecutive digital signals to effect a non-integer decimation ratio.