Simpler threshold calculation for the second filter

PSNR YCbCr:      0.03%     -0.00%      0.07%
   PSNRHVS:      0.06%
      SSIM:      0.12%
    MSSSIM:      0.09%
 CIEDE2000:      0.05%

Change-Id: I15ef9598a08f6713bc28ab98b0182310433e97ef
2 files changed