Question

What happens to the output image when global Histogram equalization method is applied on smooth and noisy area of an image?

(a) The contrast increases little bit with considerable enhancement of noise

(b) The result would have a fine noise texture

(c) All of the mentioned

(d) None of the mentioned

I had been asked this question during a job interview.

I'd like to ask this question from Histogram Specification and Use of Histogram Statistics for Image Enhancement topic in section Image Enhancement of Digital Image Processing

Answer 1

The correct choice is (a) The contrast increases little bit with considerable enhancement of noise

Easy explanation: To an image’s smooth and noisy area, when global histogram method is applied the contrast increases little bit with considerable enhancement of noise, while for local method the result has a fine noise texture.

(a) Original image. (b) Result using global histogram equalization. (c) Result using local histogram equalization using 7*7 neighborhood about each pixel.