Brightness preserving weighted dynamic range histogram equalization for image contrast enhancement

In this paper, an effective method Brightness Preserving Weighted Dynamic Range Histogram Equalization (BP-WDRHE) is proposed. Although, the Histogram Equalization (HE) is an universal method, it is not suitable for consumer electronic products because this method cannot preserve the overall brightness and the output image has unnatural looking and more visual artifacts. An extending of approach based on the Brightness Preserving Bi-Histogram Equalization method, the BPWDRHE used the weighted within-class variance as the new algorithm in separating an original histogram. Comparing with other methods using the average or the median of gray-levels, the proposed method determined a separating point based on computing the variance to minimize the total squared error of each sub-histogram corresponding to the brightness shift with HE independently. As a result, the output images obtain the comfortable visualization with preserving the overall brightness. The experimental results are presented and compared with the other brightness preserving methods.