Contrast Enhancement of Ultrasound Image of Knee Joint Cartilage by Using Multipurpose Beta Optimized Recursive Bi-Histogram Equalization Method

Multipurpose Beta Optimized Recursive Bi-histogram Equalization (MBORBHE) method has been proposed in this article for contrast enhancement of US image. Histogram equalization (HE) is very popular for contrast enhancement. But conventional HE methods do not consider brightness and detail preservation simultaneously during contrast enhancement of US image. In case of our proposed method brightness and detail preservation will be considered simultaneously during contrast enhancement of US image. For achieving this goal, a final objective function will be constructed by considering three individual objective functions named as preservation of brightness score (PBS), Optimum contrast score (OCS) and Preservation of detail score (PDS). The final objective function will be used to find out the optimum separating point for segmenting the histogram of the input US image for which brightness and detail preservation will be obtained during optimum contrast enhancement of the US image. US image of knee joint cartilage will be used for the performance evaluation of the proposed method. Qualitative analysis of the proposed method will be performed by using human visual perception. Different performance metrics named as Signal to noise ratio (SNR), Structure Similarity Index Measurement (SSIM), Entropy and shift of mean brightness will be bring into account for quantitative analysis of the proposed method. As there is a significant change of the shape of cartilage with the progression of knee Osteoarthritis (OA), so with the contrast enhanced US image of knee joint cartilage, it will be possible to detect early knee OA.