Comparative Study of Linear and Non-linear Contrast Enhancement Techniques

International Journal of Research and Scientific Innovation (IJRSI) | Volume I, Issue VI, November 2014 | ISSN 2321–2705

Comparative Study of Linear and Non-linear Contrast Enhancement Techniques

Kalpit R. Chandpa^#, Ashwini M. Jani^#, Ghanshyam I. Prajapati^#

 ^#Department of Computer Science and Information Technology, Shri S’ad Vidya Mandal Institute of Technology, Bharuch 392001, Gujarat, India

Abstract— Image enhancement is the process of improving the quality of image by using various techniques. There are so many techniques for image enhancement and every technique produces different result for different images. Contrast enhancement is one of the techniques of Image Enhancement that produces an image that subjectively looks better than the original image by changing the pixel intensities. In this paper, the various contrast enhancement techniques are compared with respect to image enhancement. We compared three cases: In the first case comparison between the linear contrast methods, in second case comparison between the non-linear contrast methods and third case comparison between linear and non-linear contrast methods. Analysis studies are explained and experiments show that Piecewise contrast method gives better result comparing with other techniques of linear contrast enhancement. For nonlinear contrast enhancement techniques, Histogram Equalization gives better result comparing with other non-linear contrast methods and non-linear contrast methods give better result than linear contrast methods.

Keywords— Linear Contrast Enhancement, Non-Linear, Contrast Enhancement, Contrast Stretching, Histogram Equalization.

I. INTRODUCTION

The main objective of image enhancement is to process a given image so that the result is more suitable than the original image for a specific application. It accentuates or sharpens image features such as edges, boundaries, or contrast to make a graphic display more helpful for display and analysis. The enhancement doesn’t increase the inherent information content of the data, but it increases the dynamic range of the chosen features so that they can be detected easily.

Contrast stretching is a simple image enhancement technique that attempts to improve the contrast in an image by `stretching’ the range of intensity values it contains to span a desired range of values.

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