Question

Which of the following statement(s) is true for the given fact that “Applying Highpass filters has an effect on the background of the output image”?

(a) The average background intensity increases to near white

(b) The average background intensity reduces to near black

(c) The average background intensity changes to a value average of black and white

(d) All of the mentioned

This question was posed to me in an interview for internship.

This interesting question is from Gaussain Lowpass and Sharpening Frequency Domain Filters topic in division Filtering in Frequency Domain of Digital Image Processing

Answer 1

Right option is (b) The average background intensity reduces to near black

Explanation: The Highpass filter eliminates the zero frequency components of the Fourier transformed image HPFs are applied on. So, the average background intensity reduces to near black.