Design of 2D FIR filters by the truncation of 2D DFTs of ideal responses

It is shown that by truncating the impulse response of an ideal 2D low-pass filter, the same impulse response can be realised by 2D finite impulse response (FIR) filters. However, the contours of the frequency response have to be taken into account while doing so. Two specific contours, namely rectangular and circular boundaries, are discussed in detail.<>