Method and an apparatus for 2-D filtering a raster scanned image in real-time

Claim 1

A two-dimensional signal processing apparatus for filtering an analog baseband video signal having raster scanned format, that is, said video signal is one being constituted by a plurality of line signals each having a pre-determined line period, said apparatus comprising: a two-dimensional filter having a transfer function H(s,z) given by ##EQU11## wherein {a ij } and {b ij } are the filter coefficients chosen to select the desired two-dimensional frequency response in regards to magnitude and phase, N an integer greater than zero, is a limit of summation corresponding to the order of the filter, s is the standard s-plane variable, z is the standard z-plane variable, X(s,z) is the input signal to said two-dimensional filter and Y(s,z) is the output signal of said two-dimensional filter; said two-dimensional filter including: at least one delay line means imparting a delay equal to substantially one horizontal line scanning period of said raster scanned signal; at least one integrating means for integrating a video signal; means for setting each of said integrating means to zero initial conditions at the beginning of each line period of said raster scan format; at least one means for generating a weighted algebraic sum of video signals being input to said weighted sum generating means; at least one means for inverting a video signal as needed to establish correct algebraic sign of weights in each of said weighted sum generating means; wherein, said delay line means, said at least one integrating means, said means for setting, said at least one weighted sum generating means, and said at least one video signal inverting means are interconnected to implement said transfer function of said two-dimensional filter.