Question

In Histogram Matching or Specification, z = G^-1[T(r)], r and z are gray level of input and output image and T & G are transformations, to confirm the single value and monotonous of G^-1  what of the following is/are required?

(a) G must be strictly monotonic

(b) G must be strictly decreasing

(c) All of the mentioned

(d) None of the mentioned

This question was addressed to me in an interview.

The query is from Histogram Specification and Use of Histogram Statistics for Image Enhancement topic in section Image Enhancement of Digital Image Processing

Answer 1

The correct option is (a) G must be strictly monotonic

For explanation: G being strictly monotonic, confirms that the values of specified histogram pz(zi) can’t be zero. That is G^-1 is also single valued and monotonic.