Threshold based Adaptive Power-Law Applications in Image Enhancement

Abstract

This paper presents a spatial domain threshold based adaptive power-law applications (TAPLA) in image enhancement technique in which adaptation is carried out with local thresholds. This is an improved version of Adaptive Power-law Transformations (APLT) [14] in which adaptation is carried out with local means. The computational time of APLT is windowsize dependent to find local mean while the TAPLA is independent of window-size to find local means, which are used to determine the local threshold values. Window-size independent of computational time is due to use of integral average image as prior process to find local mean. Like APLT, TAPLA can control the enhancement factors such as contrast, brightness and sharpness/smoothness with a proper choice of parameters through a single function. This method can be applied on both the grey scale and color images. In the case of color images, each channel is considered separately. TAPLA outperforms better than APLT in image quality as well as in computational time.