"A picture is worth one thousand words". This proverb comes from Confucius a Chinese philosopher before about 2500 years ago. Now, the essence of these words is universally understood. A picture can be magical in its ability to quickly communicate a complex story or a set of ideas that can be recalled by the viewer later in time. Visual information plays an important role in our society, it will play an increasingly pervasive role in our lives, and there will be a growing need to have these sources processed further. The pictures or images are used in many application areas like architectural and engineering design, fashion, journalism, advertising, entertainment, etc. Thus it provides the necessary opportunity for us to use the abundance of images. However, the knowledge will be useless if one can't _nd it. In the face of the substantive and increasing apace images, how to search and to retrieve the images that we interested with facility is a fatal problem: it brings a necessity for image retrieval systems. As we know, visual features of the images provide a description of their content. Content-based image retrieval (CBIR), emerged as a promising mean for retrieving images and browsing large images databases. CBIR has been a topic of intensive research in recent years. It is the process of retrieving images from a collection based on automatically extracted features.

/pdf/a-survey-of-shape-feature-extraction-techniques-3qmkhziio7.pdf

A Survey of Shape Feature Extraction Techniques

Image encryption using 2D Logistic-adjusted-Sine map

Over the years extensive studies have been carried out to apply coherent optics methods in real-time communications and image transmission. This is especially true when a large amount of information needs to be processed, e.g., in high-resolution imaging. The recent progress in data-processing networks and communication systems has considerably increased the capacity of information exchange. However, the transmitted data can be intercepted by nonauthorized people. This explains why considerable effort is being devoted at the current time to data encryption and secure transmission. In addition, only a small part of the overall information is really useful for many applications. Consequently, applications can tolerate information compression that requires important processing when the transmission bit rate is taken into account. To enable efficient and secure information exchange, it is often necessary to reduce the amount of transmitted information. In this context, much work has been undertaken using the principle of coherent optics filtering for selecting relevant information and encrypting it. Compression and encryption operations are often carried out separately, although they are strongly related and can influence each other. Optical processing methodologies, based on filtering, are described that are applicable to transmission and/or data storage. Finally, the advantages and limitations of a set of optical compression and encryption methods are discussed.

https://hal.archives-ouvertes.fr/docs/00/51/69/80/PDF/20.pdf

Optical image compression and encryption methods

Information security with optical means, such as double random phase encoding, has been investigated by various researchers. It has been demonstrated that optical technology possesses several unique characteristics for securing information compared with its electronic counterpart, such as many degrees of freedom. In this paper, we present a review of optical technologies for information security. Optical security systems are reviewed, and theoretical principles and implementation examples are presented to illustrate each optical security system. In addition, advantages and potential weaknesses of each optical security system are analyzed and discussed. It is expected that this review not only will provide a clear picture about current developments in optical security systems but also may shed some light on future developments.

Advances in optical security systems

Information security and authentication are important challenges facing society. Recent attacks by hackers on the databases of large commercial and financial companies have demonstrated that more research and development of advanced approaches are necessary to deny unauthorized access to critical data. Free space optical technology has been investigated by many researchers in information security, encryption, and authentication. The main motivation for using optics and photonics for information security is that optical waveforms possess many complex degrees of freedom such as amplitude, phase, polarization, large bandwidth, nonlinear transformations, quantum properties of photons, and multiplexing that can be combined in many ways to make information encryption more secure and more difficult to attack. This roadmap article presents an overview of the potential, recent advances, and challenges of optical security and encryption using free space optics. The roadmap on optical security is comprised of six categories that together include 16 short sections written by authors who have made relevant contributions in this field. The first category of this roadmap describes novel encryption approaches, including secure optical sensing which summarizes double random phase encryption applications and flaws [Yamaguchi], the digital holographic encryption in free space optical technique which describes encryption using multidimensional digital holography [Nomura], simultaneous encryption of multiple signals [Perez-Cabre], asymmetric methods based on information truncation [Nishchal], and dynamic encryption of video sequences [Torroba]. Asymmetric and one-way cryptosystems are analyzed by Peng. The second category is on compression for encryption. In their respective contributions, Alfalou and Stern propose similar goals involving compressed data and compressive sensing encryption. The very important area of cryptanalysis is the topic of the third category with two sections: Sheridan reviews phase retrieval algorithms to perform different attacks, whereas Situ discusses nonlinear optical encryption techniques and the development of a rigorous optical information security theory. The fourth category with two contributions reports how encryption could be implemented at the nano- or micro-scale. Naruse discusses the use of nanostructures in security applications and Carnicer proposes encoding information in a tightly focused beam. In the fifth category, encryption based on ghost imaging using single-pixel detectors is also considered. In particular, the authors [Chen, Tajahuerce] emphasize the need for more specialized hardware and image processing algorithms. Finally, in the sixth category, Mosk and Javidi analyze in their corresponding papers how quantum imaging can benefit optical encryption systems. Sources that use few photons make encryption systems much more difficult to attack, providing a secure method for authentication.

http://diposit.ub.edu/dspace/bitstream/2445/118388/1/664334.pdf

Roadmap on optical security

Optical techniques have been widely studied for securing and validating information, which is one of the most important challenges of the present time. In this work, we study simultaneous authentication of multiple input encrypted images which have been multiplexed in a single plane. The interference-based encryption architecture is used to generate two phase masks for each distinct image, which would serve as the phase lock and the phase key. The phases are made sparse by randomly retaining few pixels of the phase values. The phase locks corresponding to different images are then multiplexed in a single plane. For authenticating the phase masks, the concept of nonlinear correlation has been applied, which offer better correlation peaks than the conventional joint transform correlators. The proposed idea aims to achieve simultaneous encryption and authentication of multiple images and overcomes the constraints of storage issue.

Simultaneous authentication verification of multiple secured images using joint transform correlation approach

Three-dimensional (3D) object recognition using phase-only computer-generated Fresnel hologram (PCGFH) has been presented. The hologram is obtained with the help of symmetrical 3D Gerchberg-Saxton algorithm. The obtained PCGFHs of multi-plane object are compared to obtain the correlation outputs. The joint fractional transform correlation scheme is used to compare the holograms.

three-dimensional object recognition using phase-only computer-generated Fresnel hologram

This work aims to study the vulnerability of the phase-truncated Fourier transform (PTFT) based cryptosystem towards single key attack analysis. The existing attack algorithms aimed at retrieving the input information from the PTFT cryptosystems require the knowledge of both the encryption keys. In this work, we aim to retrieve the plaintext through phase retrieval algorithm that uses only one of the keys as its constraints. The proposed method is supported by simulation results.

Single Public Key Dependent Attack on Optical Asymmetric Cryptosystem

Three-dimensional (3D) object recognition using digital holography under varying light illumination has been demonstrated. The 3D reconstructed images obtained from digital hologram (DH) and photon limited DH are compared using nonlinear joint transform correlator.

Digital holography based 3D object recognition under varying light illumination using photon counting imaging

We propose collision in asymmetric cryptosystem based on phase-truncated Fresnel transform. An arbitrary image can be generated from ciphertext or watermark embedded in a host image with the help of phase retrieval algorithm. Computer simulation results support the idea of the proposed collision.

Naveen K. Nishchal

Papers

Simultaneous authentication verification of multiple secured images using joint transform correlation approach

three-dimensional object recognition using phase-only computer-generated Fresnel hologram

Single Public Key Dependent Attack on Optical Asymmetric Cryptosystem

Digital holography based 3D object recognition under varying light illumination using photon counting imaging

Collision in phase truncation based asymmetric cryptosystem in Fresnel domain