Hidden images in halftone pictures

Rosen, Joseph; Javidi, Bahram

doi:10.1364/ao.40.003346

Cited by 63 publications

(28 citation statements)

References 9 publications

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“…However, this process does not play an important role in the security of the system. In a more recent paper, in which this algorithm is used for image hiding [11], it is simply represented using a random phase distribution.…”

Section: B LI Et Al Methodsmentioning

confidence: 99%

“…Various algorithms have been proposed for data encryption [1][2][3][4][5][6][7][8][9][10], information hiding [11][12][13][14], watermarking [15,16], and verification [17][18][19][20][21][22][23]. These algorithms can be implemented optically by taking advantage of both the natural two-dimensional imaging capabilities of optics and the parallelism achievable with optical processing.…”

Section: Introductionmentioning

confidence: 99%

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Cryptanalysis of optical security systems with significant output images

et al. 2007

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The security of the encryption and verification techniques with significant output images is examined by a known-plaintext attack. We introduce an iterative phase-retrieval algorithm based on multiple intensity measurements to heuristically estimate the phase key in the Fourier domain by several plaintextcyphertext pairs. We obtain correlation output images with very low error by correlating the estimated key with corresponding random phase masks. Our studies show that the convergence behavior of this algorithm sensitively depends on the starting point. We also demonstrate that this algorithm can be used to attack the double random phase encoding technique.

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Section: B LI Et Al Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cryptanalysis of optical security systems with significant output images

et al. 2007

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“…This section is devoted to a new development in our general concept [3]. Not only the output but also the input signal contains a meaningful image.…”

Section: Concealogram: An Image Within An Imagementioning

confidence: 99%

“…The next generation of these security systems should offer a higher level of security and more sophisticated services than the simple verification offered by the existing systems. In this chapter, we survey three optical security systems [1][2][3] that are based on existing spatial correlators but have some additional benefits over those of the first generation. The common feature of all three systems is meaningful images on the output plane of the correlators.…”

Section: Introductionmentioning

confidence: 99%

Steganography and Encryption Systems Based on Spatial Correlators with Meaningful Output Images

Rosen

Javidi

2005

Optical and Digital Techniques for Information Security

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Summary. Three different optical security systems are surveyed in this chapter. Their common feature is the appearance of meaningful images on the system's output. In the first system, two phase-only transparencies are placed in a 4f correlator such that a known output image is received. In the second system, two phase-only transparencies are placed together in a joint-transform correlator for the same purposes. In both cases, the two phase masks are designed with an iterative optimization algorithm with constraints in the input and the output domains. In addition to simple verification, these security systems are capable of identifying the type of input mask according to the corresponding output image it generates. The third system is different from the two others in the sense that the system's input signal also is a meaningful image. This last system can offer various solutions for steganography, watermarking, and information coding. This chapter summarizes research first published in [1-3]. IntroductionOptical technologies have recently been employed in data security [4][5][6][7]. Compared with traditional computer and electrical systems, optical technologies offer primarily two types of benefits. (1) Optical systems have an inherent capability for parallel processing; that is, rapid transmission of information. (2) Information can be hidden in any of several dimensions, such as phase or spatial frequency; that is, optical systems have excellent capability for encoding information.In several pioneering studies [4][5][6], the authors demonstrated different optical verification systems for information security applications based on optical correlations. These systems correlate two functions: one, the lock, is always inside the correlator, and the other, the key, is presented to the system by the user in the verification stage. Mostly, the systems determine whether the input is true or false by detecting the correlation peak in the output plane. The next generation of these security systems should offer a higher level of security and more sophisticated services than the simple verification offered by

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“…Watermarking is an attractive information security technique, [1][2][3] which can hide authorized mark information in a cover image to achieve perceptual invisibility. The hidden watermark can be retrieved or detected for verification and authentication.…”

Section: Introductionmentioning

confidence: 99%

Correlation-based watermarking by a digital holographic technique

Cheng

2005

Opt. Eng

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Abstract. We propose and demonstrate an optical watermarking scheme using a digital holographic technique. The holographic watermark is constructed by an off-axis diffusetype hologram and embedded into a cover image with appropriate weighting. Detection of the hidden mark is optically implemented using a VanderLugt correlator with the watermarked matched filter. Detected correlation is spatially separable and avoids interference from the cover image. © 2005Society of Photo-Optical Instrumentation Engineers.

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Hidden images in halftone pictures

Cited by 63 publications

References 9 publications

Cryptanalysis of optical security systems with significant output images

Cryptanalysis of optical security systems with significant output images

Steganography and Encryption Systems Based on Spatial Correlators with Meaningful Output Images

Correlation-based watermarking by a digital holographic technique

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