Browsing by Author "Wu, DC"

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A novel block-based authentication technique for binary images by block pixel rearrangements
(2004)
Huang, PM
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Wu, DC
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Tsai, WH
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資訊工程學系
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Department of Computer Science
A novel blocked-based binary image authentication technique is proposed. The authentication signals of each 9x9 image block are placed in a selected 3x3 block within the 9x9 block. The authentication signal contains a certain relationship contributed by the standard deviation values of the other eight 3x3 blocks. Authentication signals are generated by rearranging the pixels in the selected 3x3 block. The rearrangement is designed according to a property of inverse halftoning to keep the visual change in the selected block imperceptible. By comparing the arrangement of the block pixels in a suspicious image with the extracted authentication signals, the fidelity and integrity of the image can be verified.
A steganographic method for images by pixel-value differencing
(2003-06-01)
Wu, DC
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Tsai, WH
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資訊工程學系
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Department of Computer Science
A new and efficient steganographic method for embedding secret messages into a gray-valued cover image is proposed. In the process of embedding a secret message, a cover image is partitioned into non-overlapping blocks of two consecutive pixels. A difference value is calculated from the values of the two pixels in each block. All possible difference values are classified into a number of ranges. The selection of the range intervals is based on the characteristics of human vision's sensitivity to gray value variations from smoothness to contrast. The difference value then is replaced by a new value to embed the value of a sub-stream of the secret message. The number of bits which can be embedded in a pixel pair is decided by the width of the range that the difference value belongs to. The method is designed in such a way that the modification is never out of the range interval. This method provides an easy way to produce a more imperceptible result than those yielded by simple least-significant-bit replacement methods. The embedded secret message can be extracted from the resulting stego-image without referencing the original cover image. Moreover, a pseudo-random mechanism may be used to achieve secrecy protection. Experimental results show the feasibility of the proposed method. Dual statistics attacks were also conducted to collect related data to show the security of the method. (C) 2002 Elsevier Science B.V. All rights reserved.
Data hiding in images via multiple-based number conversion and lossy compression
(1998-11-01)
Wu, DC
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Tsai, WH
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資訊工程學系
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Department of Computer Science
A novel and easy method to embed any form of secret messages into a cover image with controlled distortion is proposed. Any lossy image compressor may be applied first to a cover image to produce a lossily-processed result as the basis for embedding data in the cover image. The stego-image is produced by embedding data in each pixel of a cover image by changing its gray value without excessing the range of the gray value difference of the corresponding pixels of the cover image and its lossily-processed one. The quantity of distortion that is caused by embedding data is never in excess of that is caused by the lossy compressor. A multiple-based number system is proposed to convert the information in the secret bit stream into values to be embedded in the choosing pixels of the cover image. Pseudo-random mechanisms may be used to achieve cryptography. It is found from experiments that the values of the peaks of the signal-to-noise ratio of the stego-images are larger than those yielded by the chosen compressor, which means that the distortion in the embedding result is more imperceptible than that in the compressed one.
Data hiding in images via multiple-based number conversion and lossy compression
(1998-11-01)
Wu, DC
;
Tsai, WH
;
資訊工程學系
;
Department of Computer Science
A novel and easy method to embed any form of secret messages into a cover image with controlled distortion is proposed. Any lossy image compressor may be applied first to a cover image to produce a lossily-processed result as the basis for embedding data in the cover image. The stego-image is produced by embedding data in each pixel of a cover image by changing its gray value without excessing the range of the gray value difference of the corresponding pixels of the cover image and its lossily-processed one. The quantity of distortion that is caused by embedding data is never in excess of that is caused by the lossy compressor. A multiple-based number system is proposed to convert the information in the secret bit stream into values to be embedded in the choosing pixels of the cover image. Pseudo-random mechanisms may be used to achieve cryptography. It is found from experiments that the values of the peaks of the signal-to-noise ratio of the stego-images are larger than those yielded by the chosen compressor, which means that the distortion in the embedding result is more imperceptible than that in the compressed one.
Data hiding in stained glass images
(2005)
Hung, SC
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Wu, DC
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Tsai, WH
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交大名義發表
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National Chiao Tung University
New methods for automatic generation of stained glass images as well as for data hiding in such images are proposed. Glass regions in stained glass images are generated by randomly sprinkled seeds and a region growing technique. The number of nodes of a tree constructed for pixel grouping in a glass region is used for data hiding in a stained glass image. A complete process for secret communication using the above technique is also proposed. Experimental results show the feasibility of the proposed methods.
Embedding of any type of data in images based on a human visual model and multiple-based number conversion
(1999-12-01)
Wu, DC
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Tsai, WH
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資訊工程學系
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Department of Computer Science
A novel approach to embedding any type of digital data into a cover image is proposed, which utilizes a human visual model to guarantee that the modification of the cover image is imperceptible. A quantized contrast function based on the model is constructed first. The gray values of each 3 x 3 sub-image of the cover image are used to compute, using the function, a range of gray levels with the same contrast as that of the central pixel of the sub-image. The embedding process proceeds by replacing the gray value of the central pixel by one of the values in the range. This guarantees that the changes be imperceptible. The data to be embedded is treated as a binary stream and is partitioned into a number of sub-streams. A multiple-base number conversion mechanism is used to convert each sub-stream of data into values which are then embedded in the central pixels of sub-images. The embedded data can be extracted out from the resulting stego-image without referencing the original image. Experimental results show that the proposed method is feasible. (C) 1999 Published by Elsevier Science B.V. All rights reserved.
Spatial-domain image hiding using image differencing
(2000-02-01)
Wu, DC
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Tsai, WH
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資訊工程學系
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Department of Computer Science
A method to embed a secret image into a cover image is proposed. The method is based on the similarity among the grey values of consecutive image pixels as well as the human visual system's variation insensitivity from smooth to contrastive. A stego-image is produced by replacing the grey values of a differencing result obtained from the cover image with those of a differencing result obtained from the secret image. The process preserves the secret image with no loss and produces the stego-image with low degradation. Moreover, a pseudorandom mechanism is used to achieve cryptography. It is found from experiment that the peak values of signal-to-noise ratios of the method are high and that the resulting stego-images are imperceptible, even when the size of the secret image is about a half of the cover image.