An HD (High-Definition) Image Enhancement Algorithm for Power Line Inspection and FPGA Realization

Abstract

During power line inspection, images captured by photo-electronic imaging equipment are usually low in contrast ratio and unobvious in image details due to influence from environmental factors, such as illumination, fog, and haze, making it more difficult to find defects in power transmission line by manpower or computer. A histogram equalization image enhancement algorithm based on logarithmic transformation is proposed to solve this problem. Firstly, transform images into log-domain and apply low-pass filter to divide images into basal images with low frequency and detailed images with high frequency. Secondly, conduct histogram equalization on basal images and do linear pull-up on detailed images. Lastly, weigh the transformed basal images and detailed images, so as to obtain the reconstructed and enhanced images. The process to realize this algorithm on FPGA is given based on the above description. Experiment results showed this algorithm enhanced local detail information of the images and improved their overall contrast ratio. Besides, it also satisfied the 30f/s real-time requirement of 1080p HD image.