P.W.Wong, "A watermark for image integrity and ownership verification", in Proc IS&T PIC, Portland, Oregon, 1998.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....scales along pseudo random walks in the least significant bits (LSB) of pixels forming the walk. The main drawback of this scheme is that if the random walk is guessed it is easy to attack the image. Wong s method of fragile watermarking scheme based on cryptographic hash function is found in [2]. In this he proposes a fragile water marking scheme which divides an image into blocks, calculates the hash value from MSB of the pixels and embeds the hash sequence in the LSB of the pixels. The main drawback of this scheme is that it is subject to collage attack if the block sizes are known. ....

P.Wong, "A Watermark for Image Integrity and Ownership Verification", Proc. IS and T PIC Conference, Portland, Oregon 1998

....scales along pseudo random walks in the least significant bits (LSB) of pixels forming the walk. The main drawback of this scheme is that if the random walk is guessed it is easy to attack the image. Wong s method of fragile watermarking scheme based on cryptographic hash function is found in [2]. In this he proposes a fragile water marking scheme which divides an image into blocks, calculates the hash value from MSB of the pixels and embeds the hash sequence in the LSB of the pixels. The main drawback of this scheme is that it is subject to collage attack if the block sizes are known. ....

P. Wong, "A Watermark for Image Integrity and Ownership Verification", Proc. IS and T PIC Conference, Portland, Oregon 1998

....degradation to the original content. On the other hand, a watermark designed to detect any change whatsoever made to the content is known as a Jbagile watermark. For excellent reviews on robust and fragile watermarking techniques, the reader is referred to [5] 6] 7] Although both fragile [8] [9] and robust watermarks [10] 11] 12] have been proposed for the purposes of authentication, in this paper we focus on fragile watermarks. Fragile watermarks can be essentially viewed as a special case of cryptographic authentication techniques. However, one advantage of using fragile ....

P. W. Wong, "A watermark for image integrity and ownership verification," in Proceedings oflSl&T PIC Conference, (Portland, OR), 1998.

....of the FFT is used. 3.2 Authentication Watermarking Authentication is the process of verifying that a video stream originated from an alleged source and that the stream has not been altered or tampered. Fragile and semi fragile watermarks have been proposed to authenticate digital images [47, 48, 49, 50], but comparatively little work has been done for authenticating video. One method for authenticating video is to embed an image authentication watermark for each frame. Such a technique could detect frame dropping and insertions, but would not authenticate the synchronization between the audio ....

P. Wong, "A watermark for image integrity and ownership verification," Final Program and Proceedings of the IS&T PICS 99, pp. 374-379, Savannah, Georgia, April 1999.

....for example using the robust bit extraction algorithm proposed in [16] Anothe alternative to thwart this collage attack is to use ra ndomly placed pixels rather than publicly known 88 blocks. This may, however, somewhat negatively influence the ability to localize changes. Yeung and Wong [2,3] proposed the following method for authentication of digital images. The process of image authentication starts with a secret key that is used to ge nerate a key dependent binary valued function f, f: 0, 1, 255 0,1 , that maps integers from 0 to 255 to either 1 or 0. For color images, ....

P. Wong, "A Watermark for Image Integrity and Ownership Verification", Proc. IS&T PIC, Portland, Oregon, 1998.

....significant bits (LSB) of pseudo randomly selected pixels [1] This technique provides very high probability of tamper detection, and it can be implemented in such a manner that creating forgeries from one or multiple authenticated images is highly unlikely without a secret key. Yeung and Wong [2,3] use key dependent binary valued functions to encode a binary logo in the pixels of the digital image. The authentication step consists of checking the integrity of the binary logo using the same key dependent binary functions. This authentication fragile watermark is embedded not only in the LSBs ....

....60 55 14 13 16 24 40 57 69 56 14 17 22 29 51 87 80 62 18 22 37 56 68 109 103 77 24 35 55 64 81 104 113 92 49 64 78 87 103 121 120 101 72 92 95 98 112 100 103 99] The quantized values are further binary encoded. The bit lengths of their codes (including the signs) are shown in matrix L L=[7 7 7 5 4 3 2 1 7 6 5 5 4 2 1 0 6 5 5 4 3 1 0 0 5 5 4 3 1 0 0 0 4 4 3 1 0 0 0 0 3 2 1 0 0 0 0 0 2 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0]. Encoding based on L will guarantee that the first 11 coefficients from each block will be encoded using exactly 64 bits. In the rare event when the i th DCT coefficient has absolute value is larger than 1 2 i L , only this maximum available value will be encoded. Step 3a (Encrypting and ....

P. Wong, "A Watermark for Image Integrity and Ownership Verification", Proc. IS&T PIC, Portland, Oregon, 1998.

....Msequence in the spatial domain. Detection is via a modified correlation detector. For localization, a blocking structure is used during embedding and detection. This mark has been compared to other approaches using hash functions [9] P. Wong describes another fragile marking technique in [19], which obtains a digest using a hash function. The image, image dimensions, and marking key are hashed during embedding and used to modify the least significant bit plane of the original image. This is done in such a way that when the correct detection side information and unaltered marked image ....

P. Wong, "A watermark for image integrity and ownership verification," Final Program and Proceedings of the IS&T PICS 99, pp. 374-379, Savanna, Georgia, April 1999.

.... 1)c=2 times that of [18] Second, if we equalize the amount of embedded data, the quality of the original image will be less affected. Third, in both the above cases, a large secret key size can be used, offering a higher security. It is to be noted the digital image watermarking technology [8, 16, 17] has a different flavor from what is to be discussed in this paper. Its purpose is to embed some ownership or authentication information in an image. It is usually desirable to make a watermark visible to a certain degree, instead of completely hidden, to claim the ownership of an artwork [17] ....

....16, 17] has a different flavor from what is to be discussed in this paper. Its purpose is to embed some ownership or authentication information in an image. It is usually desirable to make a watermark visible to a certain degree, instead of completely hidden, to claim the ownership of an artwork [17]. The rest of this paper is organized as follows. Section 2 reviews the scheme of [18] Our data hiding scheme is pre1 sented in Section 3. Analysis and experimental results are in Section 4. Section 5 draws our conclusions. 2 Reviews and Motivations Below, we review the data hiding scheme ....

P. W. Wong. A Watermark for Image Integrity and Ownership Verification. In Proceedings of IS&T PIC Conference, Portland, Oregon, USA, May 1998.

....has not been modified. Early fragile watermarking systems embedded checksums [5] or pseudo random sequences [6, 7] in the least significant bit (LSB) plane of an image while more recent systems apply more sophisticated embedding mechanisms [8] including the use of cryptographic hash functions [9] to detect changes to a watermarked image. Robust and fragile watermarks are not ideal when considering information preserving transformations (such as compression) which preserve the meaning or expression of the content and information altering transformations (such as feature replacement) ....

P. Wong, "A watermark for image integrity and ownership verification," Final Program and Proceedings of the IS&T PICS 99, pp. 374-379, Savanna, Georgia, April 1999.

....a media object unless an unreasonable amount of damage has been inflicted upon it, or unless an unreasonable amount of time is spent; have been aimed at both theft detection (i.e. Digimarc s MarcSpider service) and at resolving ownership in a court of law. Fragile watermarks, such as described in [13] and [14] designed to break (but break intelligently) when an image is inappropriately altered, have been proposed for authentication of recorded media and tamper proofing documents. Robust watermarking, which is the focus of this paper, is subdivided into application domains depending on the ....

P. Wong, "A Watermark for Image Integrity and Ownership Verification." In Proceedings of IS&T PIC Conference (Portland, OR, May.). 1998.

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P.W.Wong, "A watermark for image integrity and ownership verification", in Proc IS&T PIC, Portland, Oregon, 1998.

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P. Wong, A watermark for image integrity and ownership verification, In Procs. of IS&T PIC Conference, Portland, OR. 1998.

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P. Wong, "A Watermark for Image Integrity and Ownership Verification", Proc. IS&T PIC Conference, Portland, Oregon, 1998.

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P. Wong, "A Watermark for Image Integrity and Ownership Verification", Proc. IS&T PIC Conference, Portland, Oregon, 1998.

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