Question

If h(rk) = nk, rk the kth gray level and nk total pixels with gray level rk, is a histogram in gray level range [0, L – 1]. Then how can we normalize a histogram?

(a) If each value of histogram is added by total number of pixels in image, say n, p(rk)=nk+n

(b) If each value of histogram is subtracted by total number of pixels in image, say n, p(rk)=nk-n

(c) If each value of histogram is multiplied by total number of pixels in image, say n, p(rk)=nk * n

(d) If each value of histogram is divided by total number of pixels in image, say n, p(rk)=nk / n

I had been asked this question during an online interview.

This is a very interesting question from Histogram Equalization and Processing topic in division Image Enhancement of Digital Image Processing

Answer 1

The correct choice is (d) If each value of histogram is divided by total number of pixels in image, say n, p(rk)=nk / n

The best explanation: To normalize a histogram each of its value is divided by total number of pixels in image, say n. p(rk) = nk / n.