Enhancement Ratio Optimization of Images Contrast Based on Histogram Equalization

Several methods utilizing histogram modification have been proposed for contrast enhancement. However, there has been a relative scarcity of methods capable of achieving natural and acceptable enhancement across images with varying illumination ranges. In response to this gap, this paper introduces a robust contrast enhancement algorithm composed of four stages. The image's histogram undergoes truncation utilizing a threshold equal to the mean value of intensity in the first stage. Subsequently, the truncated histogram is divided into three segments of equal pixel count during the second stage. In the third stage, each section of histogram undergoes mapping to a different dynamic range. The fourth stage involves a separate adjustment process for each histogram section. The developed technique, through meticulous control of the enhancement ratio, produces images with desirable brightness, preserving maximum details and achieving a normal enhancement in the yielded image. The performance evaluation, considering average information content and visual quality corresponding to the Mean Opinion Score (MOS), unequivocally indicates the power of the designed algorithm compared to prior methods. Furthermore, the proposed method exhibits low computational complexity, rendering it easily implementable on hardware platforms such as FPGA.

کلیدواژه ها:

Entropy ، Contrast Enhancement ، Histogram Equalization