Question

Applying Laplacian produces image having featureless background which is recovered maintaining the sharpness of Laplacian operation by either adding or subtracting it from the original image depending upon the Laplacian definition used. Which of the following is true based on above statement?

(a) If definition used has a negative center coefficient, then subtraction is done

(b) If definition used has a positive center coefficient, then subtraction is done

(c) If definition used has a negative center coefficient, then addition is done

(d) None of the mentioned

This question was posed to me during an internship interview.

The query is from Use of Second Order Derivative for Enhancement topic in portion Image Enhancement of Digital Image Processing

Answer 1

Correct option is (a) If definition used has a negative center coefficient, then subtraction is done

To explain: Applying Laplacian produces image having featureless background which is recovered maintaining the sharpness of Laplacian operation using original image either added if Laplacian definition used has a positive center coefficient  or subtracting result from original image if has a negative center coefficient.