Controlling Over Enhancement of Images Using Histogram Equalization Technique

Contrast Enhancement is a powerful technique to procure high quality images with outstanding contrast enrichment and an appreciable improvement in visual quality. A multitude of contrast enhancement schemes based on Histogram Equalization accomplished to improve image perceptibility are available in literature. Although these perform quite well, but image over enhancement is a stumbling block, which cannot be overlooked. This paper is an effort to resolve the above problem by incorporating a novel recursive approach, taking Histogram Equalization (HE) as the base methodology for improving the subjective quality of image. The proposed mechanism searches those portions of image where contrast enhancement is actually required, thus avoiding over enhancement. Furthermore, contrast adjustment is performed on the overall image so as to suppress the excessively enhanced regions. A simulator is designed in MATLAB 2016a to fulfil the defined purpose. The comparison results of proposed technique with already reported ones show that ours is better than others in terms of the performance metrics, Contrast Improvement Index(CII) and Colour Enhancement Factor (CEF). © Published under licence by IOP Publishing Ltd.