Range Limited Bi-Histogram Equalization (RLBHE)
Histogram equalization is a popular technique for enhancing image contrast. However, it tends to change the brightness of an image and hence leads to annoying artifacts. We have proposed a novel extension of histogram equalization referred to as Range Limited Bi-Histogram Equalization (RLBHE). First, RLBHE divides the input histogram into two independent sub-histograms by a threshold that minimizes the intra-class variance. This is done in order to effectively separate the objects from the background. Then, range of the equalized image is calculated to yield minimum absolute mean brightness error between the original image and the equalized one. The proposed RLBHE can achieve visually more pleasing contrast enhancement while maintaining the input brightness.
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