Digital Halftoning: Synthesis of Binary Images

Bryngdahl, Olof; Scheermesser, Thomas; Wyrowski, Frank

doi:10.1016/s0079-6638(08)70518-3

Cited by 11 publications

(7 citation statements)

References 75 publications

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“…In one of many techniques for halftone binarization [15], the various tone levels are translated to the area of binary dots. This method, termed binarization by a carrier [16], is related to the pulse-width modulation in communication theory.…”

Section: Concealogram: An Image Within An Imagementioning

confidence: 99%

“…The locations of the dots inside their cells in the halftone picture usually do not represent any information. When the positions of the dots are not uniform from cell to cell, the nonuniformity is actually used to reduce the difference between the original gray-tone image and the resultant binary image as viewed by the detection system [15].…”

Section: Concealogram: An Image Within An Imagementioning

confidence: 99%

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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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Section: Concealogram: An Image Within An Imagementioning

confidence: 99%

Section: Concealogram: An Image Within An Imagementioning

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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“…In one of many techniques for halftone binarization 1 the various tone levels are translated to the area of binary dots. This method, termed binarization by a carrier, 2 is related to the pulse-width modulation in communication theory.…”

Section: Introductionmentioning

confidence: 99%

“…When the positions of the dots are not uniform from cell to cell, the nonuniformity is actually used to reduce the difference between the original gray-tone image and the resultant binary image as viewed by the detection system. 1 We propose a method of encoding visual information in a halftone image by the locations of the dots inside their cells. The algorithm puts together two data files for two images, one that we want to print as an observable picture and the other that we want to conceal within the observable picture.…”

Section: Introductionmentioning

confidence: 99%

Concealogram: an image within an image

Rosen

Javidi²,

Goldenfeld

et al. 2002

SPIE Proceedings

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“…When the positions of the dots are not uniform from cell to cell, the nonuniformity is actually used to reduce the difference between the original gray-tone image and the resultant binary image as viewed by the detection system. 1 However, from communication theory we know that pulse-position modulation is a common method of representing information that is similar to pulse-width modulation. We propose a different method of encoding visual information in a halftone image independently of the common DAM coding in a way that is similar to pulse-position modulation.…”

Section: Introductionmentioning

confidence: 99%

Hidden images in halftone pictures

Rosen¹,

Javidi²

2001

Appl. Opt.

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A method of concealing an image in a different halftone image is proposed. Continuous-tone levels of the visible images are represented by the area of the halftone dots. However, the hidden image is encoded by the dots' positions inside their cells. Only a spatial correlator with a unique filter function can reveal the hidden image from the halftone picture. The technique and its robustness to noise and distortions are demonstrated.

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Digital Halftoning: Synthesis of Binary Images

Cited by 11 publications

References 75 publications

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

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

Concealogram: an image within an image

Hidden images in halftone pictures

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