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Colored Watermarking Technology Based on Visual Cryptography Author: Hsien-Chu Wu, Chwei-Shyong Tsai, Shu-Chuan Huang Speaker: Shu-Chuan Huang Date: May 4, 2005
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Outline Introduction The proposed method Experimental results Conclusions
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Introduction Watermarking Technology Colored Visual Cryptography
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Watermarking Technology primitive image watermark stego-image Good digital watermarking : 1. Perceptual invisible 2. Security 3. Blindness 4. Multiple watermarks 5. Robustness
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Colored Visual Cryptography
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Colored Visual Cryptography (cont.)
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The proposed method The primitive gray-level image “Lena”Colored watermark
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The proposed method (cont.)
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Random
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The proposed method (cont.) Range of mean value Mask [0, 63] [64, 127] [128, 191] [192, 255] Mean:186 The color Masks of four kinds of mean values
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coding table The proposed method (cont.)
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Experimental Results Share image 1Share image 2
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Experimental Results The recovered image from two share images
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Experimental Results (cont.) ( a ) The cropping attacked “Lena” ( b ) The recovered image from two share images of cropped “Lena”
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Experimental Results (cont.) ( a ) The blurring attacked “Lena” ( b ) The recovered image from two share images of blurred “Lena”
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Experimental Results (cont.) ( b ) The recovered image from two share images of sharpened “Lena” ( a ) The sharpening attacked “Lena”
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Conclusions Provide high robustness by using Visual Cryptography technique in Digital Watermarking. Keep the quality of primitive image.
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Watermarking Technology Based on BTC Method Author: Hsien-Chu Wu, Chwei-Shyong Tsai, I-Su Lee Speaker: I-Su Lee Date: May 4, 2005
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Outline Introduction The Proposed method Experimental results Conclusions
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Block Truncation Coding, BTC 221212189177 213194182184 192179187199 179186200169 512×512 Mean = (221+212+189+…+200+169)/16 = 191 M1 = (221+212+213+194+192+199+200)/7 = 204 M0 = (189+177+182+184+179+187+179+186+169)/9 = 181 <191 0 >191 1 1100 1100 1001 0010 bitmap
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BTC decompression 204 181 204 181 204181 204 181 204181 bitmap <191 0 >191 1 0 181 1 204 1100 1100 1001 0010 Mean = (221+212+189+…+200+169)/16 = 191 M1 = (221+212+213+194+192+199+200)/7 = 204 M0 = (189+177+182+184+179+187+179+186+169)/9 = 181
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The Proposed method 8-bit grayscale image binary watermark
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Codebook design min distance 128×128cover-image codebook
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Codebook design (cont.) codebook codebook0 codebook1 0 1
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Watermark Embedding codebook0 codebook1 cover-image binary watermark 0 1 stego-image cover-image binary watermark
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Watermark Extraction (cont.) stego-image codebook0 codebook1 0 1 binary watermark
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Experimental results (a) Lena(b) Girl(c) F16 (d) Pepper(e) Splash(f) Tiffany
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Experimental results (cont.) Cover-imagestego-image (unit:dB) BTC compression image (unit:dB) Lena 33.4100915533.69390363 Girl 37.7946339737.91506876 F16 30.9260406231.29763583 Peppers 33.0781494633.49940908 Splash 36.7610795137.12370245 Tiffany 33.0172364033.67697558 Comparison results (PSNR)
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Experimental results (cont.) (a) cropping attack watermark bit correct rate = 0.89063 watermark bit correct rate = 0.88672 (b) cropping attack
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Experimental results (cont.) bit correct rate = 0.88964 bit correct rate = 0.86230 watermark (c) cropping attack (d) cropping attack
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Experimental results (cont.) bit correct rate = 0.92969 bit correct rate = 0.86035 watermark (e) sharpening attack (f) blurring attack
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Experimental results (cont.) Cover image Lena0.890630.886720.889640.862300.929690.86035 Girl0.889650.878910.890630.861330.914060.81641 F160.885740.887690.886720.860350.921880.84375 Peppers0.885740.886720.889650.862300.925780.73730 Splash0.885740.886720.886710.863280.919920.81152 Tiffany0.852530.853510.853520.847660.935540.87890 Average0.881670.880050.882810.859540.924480.82471 Correct rate of six kinds of attacked watermark (a) cropping attack (b) cropping attack (c) cropping attack (d) cropping attack (f) sharpening attack (g) blurring attack
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Conclusions The proposed method can embed watermark in compressed images directly. It is simple and efficient to embed waterm ark in images with using BTC. Stego-image has good image quality.
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