Browsing by Author "Lin, Ja-Chen"

Now showing 1 - 20 of 33

A Sharing-Based Fragile Watermarking Method for Authentication and Self-Recovery of Image Tampering
(2008)
Chang, Yu-Jie
;
Wang, Ran-Zan
;
Lin, Ja-Chen
;
資訊工程學系
;
Department of Computer Science
This study presents an authentication method with self-recovery ability. The hidden watermark in the proposed method not only detects and locates the tampered portion of an image, but also self-recovers the tampered portion. To increase the ability to recover from tampering, the recovery data are shared by using an (r, n) threshold scheme and then scattered all over the image. Experimental results indicate that the visual quality of the watermarked image is acceptable, and that the positions of the tampered portions can be identified. Most importantly, the self-recovery result is very competitive. Copyright (C) 2008 Yu-Jie Chang et al.
All-in-one visual and computer decoding of multiple secrets: translated-flip VC with polynomial-style sharing
(2017-06-01)
Wu, Chia-Hua
;
Lee, Suiang-Shyan
;
Lin, Ja-Chen
;
資訊工程學系
;
Department of Computer Science
This all-in-one hiding method creates two transparencies that have several decoding options: visual decoding with or without translation flipping and computer decoding. In visual decoding, two less-important (or fake) binary secret images S1 and S2 can be revealed. S1 is viewed by the direct stacking of two transparencies. S2 is viewed by flipping one transparency and translating the other to a specified coordinate before stacking. Finally, important/true secret files can be decrypted by a computer using the information extracted from transparencies. The encoding process to hide this information includes the translated-flip visual cryptography, block types, the ways to use polynomial-style sharing, and linear congruential generator. If a thief obtained both transparencies, which are stored in distinct places, he still needs to find the values of keys used in computer decoding to break through after viewing S1 and/or S2 by stacking. However, the thief might just try every other kind of stacking and finally quit finding more secrets; for computer decoding is totally different from stacking decoding. Unlike traditional image hiding that uses images as host media, our method hides fine gray-level images in binary transparencies. Thus, our host media are transparencies. Comparisons and analysis are provided. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)
An accelerated K-means clustering algorithm using selection and erasure rules
(2012-10-01)
Lee, Suiang-Shyan
;
Lin, Ja-Chen
;
資訊工程學系
;
Department of Computer Science
The K-means method is a well-known clustering algorithm with an extensive range of applications, such as biological classification, disease analysis, data mining, and image compression. However, the plain K-means method is not fast when the number of clusters or the number of data points becomes large. A modified K-means algorithm was presented by Fahim et al. (2006). The modified algorithm produced clusters whose mean square error was very similar to that of the plain K-means, but the execution time was shorter. In this study, we try to further increase its speed. There are two rules in our method: a selection rule, used to acquire a good candidate as the initial center to be checked, and an erasure rule, used to delete one or many unqualified centers each time a specified condition is satisfied. Our clustering results are identical to those of Fahim et al. (2006). However, our method further cuts computation time when the number of clusters increases. The mathematical reasoning used in our design is included.
An improved module-based substitution method for image hiding
(2008)
Chen, Shang-Kuan
;
Lin, Ja-Chen
;
Fu, Hung-Lin
;
應用數學系
;
資訊工程學系
The paper proposes an improved module-based substitution method for image hiding. The method has the following characteristics: (1) The extracted data are lossless. (2) Each k-bit datum is hidden in a pixel of the host image, and the gray-value distortion is not larger than 2(k-1) for most of the pixels. (3) If it is compared with reported lossless Least-Significant-Bits (LSB) or module-based methods, the proposed method is often with better stego-image quality, unless the hidden data are with very strong randomness. (4) The time complexity is also competitive.
Authentication and cross-recovery for multiple images
(2008-10-01)
Chang, Yu-Jie
;
Lin, Sian-Jheng
;
Lin, Ja-Chen
;
資訊工程學系
;
Department of Computer Science
We propose a system with image authentication and cross-recovery ability to protect a group of n given digital images. The system is a (r, n) threshold scheme (r is a prespecified threshold satisfying 2 <= r < n). Any r of these images can reconstruct the whole group of n images, but less than r images cannot. Therefore the system has cross-recovery ability because if some [up to (n-r)] images in the group are destroyed or lost in a distributed storage scheme or transmission mission, the destroyed or lost can be rebuilt vividly by the mutual support of r survived members. The design is composed of compression, a two-layer sharing, cryptographic hash function, and information hiding. (C) 2008 SPIE and IS&T.
AUTHENTICATION AND CROSS-RECOVERY OF MULTIPLE IMAGES
(2011-07-01)
Chen, Lee Shu-Teng
;
Chen, Shang-Kuan
;
Lin, Ja-Chen
;
資訊工程學系
;
Department of Computer Science
This work presents an authentication and cross-recovery scheme to protect a group of n JPEG images. Given n images, the images are scaled down and then encoded using JPEG to create n recovery data. Based on a pre-determined threshold t, 2 <= t < n, the n recovery data are shared to create n shadows. Next, n authentication data are generated to identify malicious attacks on the system. Additionally, the n shadows and the n authentication data are embedded in the n JPEG codes of the n original images to form n JPEG stego codes, which can be stored in a distributed storage system. Moreover, in the daily maintenance of the storage system, the authentication data concealed inside these n JPEG stego codes are used to verify which ones have been attacked. If some (up to n - t) of the n JPEG stego codes are corrupted, the corrupted JPEG images can be recovered approximately using any t survived JPEG stego codes. Experimental results demonstrate the effectiveness of the proposed method. Comparisons with other image recovery methods are also included.
Authentication and recovery of an image by sharing and lattice-embedding
(2010-10-01)
Lin, Sian-Jheng
;
Lin, Ja-Chen
;
資訊工程學系
;
Department of Computer Science
Based on sharing and lattice-embedding techniques, we present an authentication-recovery method for an image. The recovery data are shared among many shadows, then lattice-embedding is utilized to embed each shadow in the discrete cosine transform domain of an 8x8 block. The proposed method can resist certain content-preserving operations such as JPEG compression, Gaussian noise, and brightness adjustment, up to a tolerance level controlled by a quantization parameter value. The method can also resist certain security attacks such as a cut-and-paste attack, a collage attack, and a vector quantization attack. Compared with previous works, the proposed method has following major advantages and novelty: (1) the method does not require prediction of the tampering trace, and the tampered blocks are always recovered as long as the number of valid blocks reaches a threshold and (2) lattice-embedding yields smaller distortion than does parity-check quantization, and the latter was often used in reported works. (C) 2010 SPIE and IS&T. [DOI: 10.1117/1.3500799]
Data hiding using VQ index file
(2008)
Chang, Yu-Jie
;
Lin, Ja-Chen
;
資訊工程學系
;
Department of Computer Science
This paper modifies an elegant data hiding method of Chang et al's [Pattern Recog. Lett. 2004, vol. 25, no. 11, 1253-1261]. The embedding employs a modified search-order coding (SOC) technique to hide binary secret data in the vector quantization (VQ) index file of a host image. The recovered host image is identical to the one recovered by traditional VQ; the compression rate is competitive to traditional VQ's (often better than traditional VQ's if we use t = 1 mode); while the hidden binary data is revealed in the decompression procedure as a bonus. The compression rate and hiding capacity are also better than those in Chang et al's.
Error Correction of Secret Images by Search Order Coding
(2009)
Su, Wei-Kai
;
Chen, Lee Shu-Teng
;
Lin, Ja-Chen
;
資訊工程學系
;
Department of Computer Science
In this paper, an image recovery method based on search-order coding (SOC) is proposed. By using SOC, a SOC-image of the secret image can be generated. If the secret Image is damaged, people can still obtain a version of the secret image that looks not bad by referring to the SOC-image. Also, the information of the secret image cannot be retrieved from the SOC-image alone.
Fast-weighted secret image sharing
(2009-07-01)
Lin, Sian-Jheng
;
Chen, Lee Shu-Teng
;
Lin, Ja-Chen
;
資訊工程學系
;
Department of Computer Science
Thien and Lin [Comput. and Graphics 26(5), 765-770 (2002)] proposed a threshold scheme to share a secret image among n shadows: any t of the n shadows can recover the secret, whereas t-1 or fewer shadows cannot. However, in real life, certain managers probably play key roles to run a company and thus need special authority to recover the secret in managers' meeting. (Each manager's shadow should be more powerful than an ordinary employee's shadow.) In Thien and Lin's scheme, if a company has less than t managers, then manager's meeting cannot recover the secret, unless some managers were given multiple shadows in advance. But this compromise causes managers inconvenience because too many shadows were to be kept daily and carried to the meeting. To solve this dilemma, a weighted sharing method is proposed: each of the shadows has a weight. The secret is recovered if and only if the total weights (rather than the number) of received shadows is at least t. The properties of GF(2(r)) are utilized to accelerate sharing speed. Besides, the method is also a more general approach to polynomial-based sharing. Moreover, for convenience, each person keeps only one shadow and only one shadow index. (C) 2009 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3168644]
Fault-tolerant VQ-style Secret Image Sharing
(2009)
Su, Wei-Kai
;
Chen, Lee Shu-Teng
;
Lin, Ja-Chen
;
資訊工程學系
;
Department of Computer Science
In this paper, we propose a fault-tolerant secret image sharing scheme based on vector quantization (VQ). The proposed method uses some of the n host images to generate the codebooks for VQ, and compresses the secret image by VQ with the generated codebooks. The VQ indices are thus created and then shared among n shadows. After obtaining the n shadows, they are embedded together with the mixed information of the generated codebooks into the n host images to form the n stego-images. When collecting any r (r <= n) of the n stego-images, the VQ indices and codebooks can be retrieved to recover the secret image. However, no information about the secret image can be revealed if obtaining less than r stego-images. Because of using VQ, the secret image is compressed to the VQ indices, and thus easier to be hidden than the non-compressed one. The quality of the recovered image is the same as the one of the ordinary VQ.
Flip visual cryptography (FVC) with perfect security, conditionally-optimal contrast, and no expansion
(2010-11-01)
Lin, Sian-Jheng
;
Chen, Shang-Kuan
;
Lin, Ja-Chen
;
資訊工程學系
;
Department of Computer Science
This paper proposes a flip visual cryptography (FVC) scheme with perfect security, conditionally optimal contrast, and no expansion of size. The proposed FVC scheme encodes two secret images into two dual-purpose transparencies. Stacking the two transparencies can reveal one secret image. Flipping one of the two transparencies and then stacking with the other transparency can reveal the second secret image. The proposed scheme is proved to have conditionally optimal contrast: its contrast is optimal if the double-secrets non-expanded FVC scheme is required to have perfect security. The perfect security is also proved. (c) 2010 Elsevier Inc. All rights reserved.
Flip visual cryptography (FVC) with perfect security, conditionally-optimal contrast, and no expansion
(2010-11-01)
Lin, Sian-Jheng
;
Chen, Shang-Kuan
;
Lin, Ja-Chen
;
資訊工程學系
;
Department of Computer Science
This paper proposes a flip visual cryptography (FVC) scheme with perfect security, conditionally optimal contrast, and no expansion of size. The proposed FVC scheme encodes two secret images into two dual-purpose transparencies. Stacking the two transparencies can reveal one secret image. Flipping one of the two transparencies and then stacking with the other transparency can reveal the second secret image. The proposed scheme is proved to have conditionally optimal contrast: its contrast is optimal if the double-secrets non-expanded FVC scheme is required to have perfect security. The perfect security is also proved. (c) 2010 Elsevier Inc. All rights reserved.
HIDING IMAGES USING MODIFIED SEARCH-ORDER CODING AND MODULUS FUNCTION
(2008-09-01)
Chang, Yu-Jie
;
Wang, Ran-Zan
;
Lin, Ja-Chen
;
資訊工程學系
;
Department of Computer Science
This paper proposes a method for hiding an important image in a cover image whose size is limited. In this method, in order to save space, a modified search-order coding (MSOC) technique first transforms the important image, then, a randomization procedure permutes the transformed image to further increase the security. Finally, a modulus function embeds the permuted code in a cover image; notably, in the modules function, the modulus base used for a pixel is determined according to the variance of its neighboring pixels. Experimental results show that the images are of high quality. Comparisons with reported methods are provided.
Image hiding by base-oriented algorithm
(2006-11-01)
Yang, Ching-Yu
;
Lin, Ja-Chen
;
資訊工程學系
;
Department of Computer Science
We propose a method called the base-oriented algorithm for image hiding. The method classifies each block of the host image H according to the base value (BV) that represents the block's variation. The classified blocks then either uses BV embedding or module substitution to hide data. The hiding capability of the proposed method is high, whereas the visual performance is also good. The lossless extraction of the confidential image from the mixed image is simple and uses no look-up table. The method can be used as an economic tool to hide and store confidential data in images. (c) 2006 Society of Photo-Optical Instrumentation Engineers.
Image hiding by LSB matching of higher payload
(2012)
Chen, Shang-Kuan
;
Lin, Ja-Chen
;
交大名義發表
;
National Chiao Tung University
LSB (Least significant bit) matching is a data hiding method that embeds message bits into a cover image by adding 0 or 1 or -1 to every cover pixel. Previous LSB matching methods were designed with 1 bpp (bits per pixel) as payload. By equalizing two values of distinct bases, the proposed LSB matching method can have a payload which is adjustable by the users, and the range is between 0 and 1.5849 bpp. Experimental results show that the quality of our stego-images is also competitive.
Multithreshold progressive image sharing with compact shadows
(2010-01-01)
Chen, Lee Shu-Teng
;
Lin, Ja-Chen
;
資訊工程學系
;
Department of Computer Science
We propose a multithreshold progressive reconstruction method. The image is encoded three times using Joint Photographic Experts Group (JPEG): first with a low-quality factor, then with a medium-quality factor, and last with a high-quality factor. Huffman coding is employed to encode the difference between the important image and the high-quality JPEG decompressed image. The three JPEG codes and the Huffman code are shared, respectively, according to four prespecified thresholds. The n-generated equally important shadows can be stored or transmitted using n channels in parallel. Cooperation among these generated shadows can progressively reconstruct the important image. The reconstructed image is loss-free when the number of collected shadows reaches the largest threshold. Each shadow is very compact and so can be hidden successfully in the JPEG codes of cover images to reduce the probability of being attacked when transmitted in an unfriendly environment. Comparisons with other image sharing methods are made. The contributions, such as easiness to apply to scalable Moving Picture Experts Group (MPEG) video transmission or resistance to differential attack, are also included. (C) 2010 SPIE and IS&T. [DOI: 10.1117/1.3295710]
Progressive sharing of an image
(2008-04-01)
Hung, Kuo-Hsien
;
Chang, Yu-Jie
;
Lin, Ja-Chen
;
資訊工程學系
;
Department of Computer Science
We propose a sharing method to progressively reveal a given important image in the recovery phase. In the encoding phase, the distributor utilizes the three frequency bands (low, middle, and high) of the given image to generate shadows according to three prespecified thresholds. In the recovery phase, the secret image cannot be revealed if the number of shadows a team collects is less than the lowest threshold. However, when the number of collected shadows reaches the prespecified low (or middle- or high) threshold, the team can reconstruct a low- (or middle- or high-) quality version of the secret image. In other words, the quality of the reconstructed image depends only on the number of shadows being received, rather than on which of the generated shadows are received. Each noise-like shadow is so small that it can be hidden in an ordinary image that is still several times smaller than the original image. (C) 2008 Society of Photo-Optical Instrumentation Engineers.
Progressive sharing of multiple images with sensitivity-controlled decoding
(2015-02-14)
Chang, Sheng-Yu
;
Lee, Suiang-Shyan
;
Yeh, Tzu-Min
;
Chen, Lee Shu-Teng
;
Lin, Ja-Chen
Secure sharing of digital images is becoming an important issue. Consequently, many schemes for ensuring image sharing security have been proposed. However, existing approaches focus on the sharing of a single image, rather than multiple images. We propose three kinds of sharing methods that progressively reveal n given secret images according to the sensitivity level of each image. Method 1 divides each secret image into n parts and then combines and hides the parts of the images to get n steganographic (stego) JPEG codes of equal importance. Method 2 is similar; however, it allocates different stego JPEG codes of different 'weights' to indicate their strength. Method 3 first applies traditional threshold-sharing to the n secret images, then progressively shares k keys, and finally combines the two sharing results to get n stego JPEG codes. In the recovery phase, various parameters are compared to a pre-specified low/middle/high (L/M/H) threshold and, according to the respective method, determine whether or not secret images are reconstructed and the quality of the images reconstructed. The results of experiments conducted verify the efficacy of our methods.
Protection of 3D models using cross recovery
(2017-01)
Lee, Suiang-Shyan
;
Huang, Yi-Jheng
;
Lin, Ja-Chen
;
資訊工程學系
;
Department of Computer Science
This paper proposes a cross recovery scheme to protect a group of 3D models. The lost or damaged models can be reconstructed using the mutual support of the survived authenticated models. In the encoding phase, we convert a group of n given models (called host models) into n stego* models. The n stego* models would still preserve the appearance of the n host models. In the decoding phase, we divide the received models into two groups: authenticated vs. non-authenticated. Then, we rebuild the recovered models of the non-authenticated group by the mutual support of any t authenticated models (t < n is a given parameter). The experimental results show that the visual quality of our stego* models is very similar to that of the host models, and the size of the stego* models is also very similar to that of the host models. Moreover, after hacker\'s attack or disk crash, if the number of attacked or crashed stego* models is not larger than n - t, then the damaged or lost models can be recovered, and the recovered models still have acceptable quality. We also provide an equation which can estimate the suitable size of the recovered model in advance.