Experimental results for 2000 measurements. (a) Original object; (b) traditional GI image, PSNR = 9.3702 dB and Q = 0.2624; (c) DGI image, PSNR=11.3125 dB and Q = 0.3651; (d) NGI image, with PSNR=11.4031 dB and Q = 0.3738; (e) MDGI image, PSNR=16.5296 dB and Q = 0.6653; (f) MDGI1 image, PSNR=14.8747 dB and Q = 0.5535.