Question

What is the technique for a gray-level transformation function called, if the transformation would be to produce an image of higher contrast than the original by darkening the levels below some gray-level m and brightening the levels above m in the original image.

(a) Contouring

(b) Contrast stretching

(c) Mask processing

(d) Point processing

I had been asked this question in unit test.

The above asked question is from Relationship between Pixels and Image Enhancement Basics topic in chapter Image Enhancement of Digital Image Processing

Answer 1

The correct option is (b) Contrast stretching

Best explanation: For a gray-level transformation function “s=T(r)”, where r and s are the gray-level of f(x, y) (input image) and g(x, y) (output image) respectively at any point (x, y).

Then the technique, contrast stretching compresses the value of r below m by transformation function into a narrow range of s, towards black and brightens the value of r above m.