Question

When is the contrast stretching transformation a linear function, for r and s as gray-value of image before and after processing respectively?

(a) r1 = s1 and r2 = s2

(b) r1 = r2, s1 = 0 and s2 = L – 1, L is the max gray value allowed

(c) r1 = 1 and r2 = 0

(d) None of the mentioned

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

Asked question is from Piecewise-Linear Transformation Functions topic in portion Intensity Transformations and Spatial Filtering of Digital Image Processing

Answer 1

Correct option is (a) r1 = s1 and r2 = s2

The best I can explain: If r1 = s1 and r2 = s2 the contrast stretching transformation is a linear function.