EVALUATION OF DEBLOCKING METHODS FOR CHANG’E-4 DESCENT IMAGES

Abstract. Chang’e-4 lunar probe has successfully landed on the far side of the moon in Von Kármán crater inside the South Pole-Aitken (SPA) basin at 10:26 am on January 3, 2019. Due to the reduction of the coding rate, obvious block effects appear at the boundaries of descent images. Unblock, adaptive fast bilateral filtering, structure-texture enhancement and high-order Markov random field methods, are applied to remove the block effect of the descent images. Based on analysing the quality of descent images, quantitative comparison of four methods is performed using simulated compressed 1:64 descent images and real images. Comprehensive analysis was performed using typical measures such as PSNR, SSIM and NIQE. Experimental results show that adaptive fast bilateral filtering is better than other methods. The deblocked 1:64 image sequences have been used to assist localizing the landing point quickly during the mission.