 Therefore, a 3-D spatially planar signal, is constant on 3 surfaces and is given by formula_440formula_41 + formula_442formula_42 + formula_453formula_454 = d, for formula_31d formula_448R
It may be shown that the 3-D DFT of a SP ' yields 3-D DFT frequency domain coefficients, ', which are zero everywhere except on the line where
A 3-D signal input sequence will be selectively enhanced by a 3-D passband enclosing this line.Thus we make use of a cone filter having a thin pyramidal shaped passband which is approximated using Mixed filter constructed using 2-D DHT.Firstly, we have to select the passband regions on {k1,k2}.