文件列表:

PQ_matlab\BatchPQ.m (31830, 2008-07-21)
PQ_matlab\DCT.c (9434, 2006-06-17)
PQ_matlab\DCT.mexw32 (7168, 2008-07-21)
PQ_matlab\IDCT.c (13679, 2006-06-17)
PQ_matlab\IDCT.mexw32 (8192, 2008-07-21)
PQ_matlab\input_dir\img_1200.jpg (64424, 2008-07-21)
PQ_matlab\input_dir\img_1230.jpg (86388, 2008-07-21)
PQ_matlab\jpeg_read.mexa64 (17765, 2005-06-01)
PQ_matlab\jpeg_read.mexw32 (65536, 2007-02-14)
PQ_matlab\jpeg_write.mexa64 (17263, 2005-06-01)
PQ_matlab\jpeg_write.mexw32 (57344, 2006-09-04)
PQ_matlab\output_dir\cover\img_1200.jpg (47138, 2008-07-21)
PQ_matlab\output_dir\cover\img_1230.jpg (63559, 2008-07-21)
PQ_matlab\output_dir\img_1200.jpg (47087, 2008-07-21)
PQ_matlab\output_dir\img_1230.jpg (63371, 2008-07-21)
PQ_matlab\output_dir\logs\21-Jul-2008.log (757, 2008-07-21)
PQ_matlab\PQ_matlab.zip (447921, 2014-05-06)
PQ_matlab\output_dir\cover (0, 2010-03-27)
PQ_matlab\output_dir\logs (0, 2010-03-27)
PQ_matlab\input_dir (0, 2010-03-27)
PQ_matlab\output_dir (0, 2010-03-27)
PQ_matlab (0, 2014-05-07)

NAME Perturbed Quantization Steganography DISCLAIMER Copyright (c) DDE Lab, SUNY Binghamton, 2007-2008 AUTHOR Jan Kodovsky CONTACT Jan Kodovsky, jan@kodovsky.com Jessica Fridrich, fridrich@binghamton.edu DESCRIPTION This matlab code performs batch Perturbed Quantization Steganography on all the images in the given directory. It includes both original PQ and its mo- dified versions PQt and PQe as described in [1]. Before you start, make sure you compile both 'DCT.c' and 'IDCT.c' pro- grams using the MATLAB's mex command. You will also need to compile Phil Sallee's jpeg_read.c and jpeg_write functions. For your convenience, in our sourcecode we enclose a few precompiled versions of all the mentioned fun- ctions, working on different platforms. In case none of these precompiled versions works on your platform, you need to compile it on your own. In that case, you need to download Phil Sallee's JPEG toolbox sourcecodes from this location: http://www.sqrtpi.com/Software/jpegtbx_1.4.tar.gz as well as the jpeglib library which Phil Sallee uses: ftp://ftp.uu.net/graphics/jpeg/jpegsrc.v6b.tar.gz. The main function is BatchPQ, taking the following arguments: method - what selection strategy should be applied for choosing the co- efficients for embedding. Implemented so far: - 'pq' - original pq method - midpoint - 'pqt' - texture based strategy - into most textured areas - '-pqt' - texture based strategy - into least textured areas - 'pqe' - DCT energy based strategy capacity - desired embedding capacity input_dir - input directory with source JPEG images of the required quali- ty factor output_dir - output directory, here the embedded images will be saved keep_covers - should the covers (just double-compressed images, with no embedding changes) be preserved after the whole process? - 1 => covers will be preserved - 0 => covers will not be preserved seed - PRNG seed Please report bugs or suggestions to jan@kodovsky.com. EXAMPLE BatchPQ('pqt',0.10,'input_dir','output_dir',1,171); In the directory 'input_dir' are two jpeg images with the quality factor 85. The BatchPQ function takes both these images and performs Perturbed Quanti- zation steganography on them, one by one. The stegoimages are stored in the directory 'output_dir'. The textured based selection rule is applied in this case, and the message length is 10% of the number of nonzero AC coefficients (this could be modified in the code in order to calculate the capacity from the number of all the nonzero c oefficients, DC terms included). The mes- sage was generated using PRNG with the seed 171. The cover images are double compressed images with the quality factors 85 and 70 and after the whole process, they will be stored in the directory 'output_dir/cover'. Detailed logfile will be saved in the subdirectory 'output_dir/logs'. LIMITATIONS OF THIS BATCH RELEASE: - parameters Q1 and Q2 are fixed to Q1=85 and Q2=70. This is good combination for PQ and we don't want to deal with the issue of checking wheter all the source images are of the required quality factor. So for now, all the source images should be of the quality factor 85 and the responsibility for this is completely up to the user. - embedding of pseudorandom bitstreams only - not the issue in fact, all the messages could be transcoded into such bitstreams REFERENCES [1] J. Fridrich, T. Pevny, and J. Kodovsky. Statistically undetectable JPEG ste- ganography: Dead ends, challenges, and opportunities. In J. Dittmann and J. Fridrich, editors, Proceedings of the 9th ACM Multimedia & Security Work- shop, pages 3-14, Dallas, TX, September 20-21, 2007.

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