Question

If D0 is the cutoff distance measured from origin of frequency rectangle and D(u, v) is the distance from point(u, v). Then what value does an Ideal Highpass filter will give if D(u, v) ≤ D0 andifD(u, v) >D0?

(a) 0 and 1 respectively

(b) 1 and 0 respectively

(c) 1 in both case

(d) 0 in both case

I had been asked this question in semester exam.

This intriguing question comes from Gaussain Lowpass and Sharpening Frequency Domain Filters topic in chapter Filtering in Frequency Domain of Digital Image Processing

Answer 1

Correct option is (a) 0 and 1 respectively

Easiest explanation: Unlike Ideal lowpass filter, an Ideal highpass filter attenuates the low-frequency components and so gives 0 for D(u, v) ≤ D0 and 1 for D(u, v) >D0.