2 2 Coltuc 2) A Zeng 3) B JPEG JPEG JPEG JPEG JPEG JPEG JPEG 3 1) Exif JPEG 2) 3) JPEG A Exif A 2) 3) B DCT JPEG Exif DCT a) b) Coltuc JPEG c) a) 1) b

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1 IIEEJ JPEG, Protection of Privacy in JPEG Files Using Reversible Information Hiding Fuyuki MASUTANI, Michiharu NIIMI (Member), Hideki NODA Graduate School of Computer Science and Systems Engineering, Kyushu Institute of Technology, Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology JPEG Exif Coltuc 1 Exif Zeng JPEG <Summary> The privacy of unknown person may be included in the digital images unintentionally taken as a sight. The action of the file upload of it would occur invasion of his/her privacy. The JPEG files may include Exif information which is regarded as personal privacy. For these two privacy problems, we propose two privacy protection techniques for JPEG files using reversible information hiding. One is to be able to protect personal privacy if we embed an Exif information into the privacy region. The other is to be able to protect personal privacy when we erase Exif information from the JPEG format and degrade the privacy region by adding some noise. In addition, we embed Exif information and the Huffman code of DCT coefficients in the privacy region into a whole image. In the experiments, we show an example of privacy protection and investigate the feasibility of our method in the real world. Keywords: reversibale informaiton hiding, JPEG image, privacy protection 1. JPEG 2 JPEG Exif ( GPS ) 1) 1) JPEG 21

2 2 2 Coltuc 2) A Zeng 3) B JPEG JPEG JPEG JPEG JPEG JPEG JPEG 3 1) Exif JPEG 2) 3) JPEG A Exif A 2) 3) B DCT JPEG Exif DCT a) b) Coltuc JPEG c) a) 1) b) Coltuc JPEG c) 4)Motion-JPEG 5) JPEG DCT JPEG JPEG JPEG DCT JPEG 2. A B 2.1 Coltuc N x i i =1,...,N log 2 n[bpp] n n>1y i (1) i =1,...,N 1 y i =(n +1)x i nx i+1 (1) y i (2) 0 (n +1)x i nx i+1 + n 255 (2) (2) (1) (3) y i + nx i+1 0mod(n +1) (3) 1 n w i (1) w i y i y i + w i (4) (4) w i y i (3) (2) (1) (5) c i c i =(x i + nx i+1 )mod(n +1) (5) c i [0,n] c i (3) x i x i c i (6) c i w i i = N 1,...,1 22

3 i = N 1,...,1 (3) (7) x i = y i w i + nx i+1 n +1 (7) (3) c i Coltuc (x i ) 2.2 Zeng 1bit JPEG m n m n M { 1, i,j M(i, j) = 1, i,j (8) i [0,m 1],j [0,n 1] M α m n α (k) = C (k) (i, j) M(i, j) (9) i=1 j=1 (k) k C (k) (i, j) k (i, j) T α α MAX T = α MAX 0 1 α C (k) (i, j)+m(i, j) β, α 0 and M(i, j) =1or S (k) α<0and M(i, j) = 1 (i, j) = C (k) (10) (i, j) M(i, j) β, α 0 and M(i, j) = 1 or α<0and M(i, j) =1 β [1, 254] S (k) (i, j) α (9) T α T 0 α >T 1 1 DCT Fig. 1 Scannnig order of DCT coefficients within a block 1 S (k) (i, j) M(i, j) β, α TandM(i, j) =1or C (k) α< T andm(i, j) = 1 (i, j) = S (k) (11) (i, j)+m(i, j) β, α TandM(i, j) = 1 or α< T andm(i, j) = Coltuc ( A) Exif Coltuc Exif Coltuc JPEG Coltuc JPEG JPEG DCT Coltuc JPEG x i,i = S,...,N(1 S<N 61) DCT DCT Coltuc S N 1 1 log 2 n[bit](2 n 512) x i (12) (13) x i y i 0 (n +1) x i n x i+1 + n 1023 (12) y i =(n +1) x i n x i+1 (13) x i x i w i [1,n] y i w i 23

4 x i (12) (14) c i x i c i =( x i + n x i+1 )mod(n +1) (14) DCT i = N,...,S c i w i (15) { x 2 log 2 (n+1) (n 64) j x j (15) (n<64) j = N +1,N+2 x i,x j < 0 i, j i = N...,S (16) (y i + n x i+1 )mod(n +1)=0 (16) (16) (17) x i = y i + n x i+1 n +1 (17) (16) c i A 1. JPEG 2. Exif JPEG 3. Exif A 1. Coltuc DCT x S x N 2. n 3. Exif Exif Zeng ( B) [bit] JPEG DCT (x i,i=0,...,63) (x i,i=1, 2, 3) (x i,i=4,...,63) 0 DCT Exif Zeng B 1. JPEG Exif (Exif ) 4. DCT Exif (RS 6) ) 5. 4 RS B 1. JPEG 8x8 2. β 3. T JPEG JPEG Exif 9,726byte A Exif PSNR 4 S n PSNR 5 S =1 24

5 2 Fig. 2 Experimental image 5 PSNR Fig. 5 PSNR with the number of DCT coefficients for embedding varied 3 Fig. 3 A part of privacy region Fig. 6 6 A Privacy protected image by method A 4.2 B 4 PSNR Fig. 4 PSNR with the starting point of DCT coefficients for embedding varied N n PSNR 6 Exif S =46,N =62,n =64 PSNR [db] JPEG 1 DCT PSNR A DCT [bit] ,000bit Exif 9,726byte Exif 2,558byte DCT 6,364byte zip 7,980byte 120,000bit RS 23.4% 14,960byte (Exif DCT ) JPEG β β T α MAX α 2 25

6 1 [%] Table 1 Error rate for each parameter [%] β Fig. 7 7 B Privacy protected image by method B 2 T α [%] Table 2 Error rate with T varied using α distributions [%] 3 Table 3 β T PSNR [db] PSNR for Fig.6 and Fig.7 based on Fig.3 [db] 6 PSNR PSNR PSNR ( 3) Exif JPEG Exif JPEG 2 A B A A Coltuc 1 DCT DCT x S x N 3 A Coltuc DCT 3 B Zeng DCT DCT JPEG A B A 3 Exif 2 1 Exif 1 Exif A B PSNR JPEG JPEG Exif OpenCV 7) Coltuc Zeng 26

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