Research Article

Coverless Steganography Based on Motion Analysis of Video

Algorithm 4

Improved index database construction.
Input: video database , number of the videos d, frame averaging window length avg_L, smoothing window size for the optical flow calculation W, number of the LK pyramid level L, and bin number N
Output: video index database
(1)For i = 1 : d
(2)Decompose video to pictures: P = VideoToFrame (Vi)
(3)For j = 1: FrameNum-avg_L + 1
(4)Initialize R_sum as all zero
(5)For k = 0: avg_L − 1
(6)Convert RGB to gray: orig_Rj+k = Rgb2gray (Pj+k)
(7)R_sum = R_sum + orig_Rj+k
(8)End for
(9)R j = R_sum/avg_L
(10)End for
(11)For j = 1: FrameNum − avg_L
(12)Repeat step 1–10 of Algorithm 1.
(13)End for
(14)End for