An Adaptive Image Enhancement Algorithm Based on Zone System

The main objective of image enhancement is to improve the visual quality of digital images that are captured under extremely low or non-uniform lighting conditions. We present an adaptive image enhancement algorithm based on Zone System. This study reveals hidden image details and increases the contrast of an image with low dynamic range. It is comprised two processes: adaptive luminance enhancement and adaptive contrast enhancement. The adaptive luminance enhancement algorithm is a global intensity transform function based on Zone System information. This process not only increases the luminance of darker pixels but also compresses the dynamic range of the image. The adaptive contrast enhancement adjusts the intensity of each pixel based on the discontinuities of the local luminance. It also improves the contrast of local region and reveals the details of image clearly. The proposed algorithm has good performance on enhancing contrast, preserving more detail of characteristics and sharpening edges of objects in experimental results. The performance with our proposed was better evaluation and comparison than other algorithms in the subjective and objective evaluation.