Enhanced Visual Cryptographic Schemes with Essential Access Structures and Pixel-Wise Operations

With fast growth in Internet and digital imaging knowledge, there are progressive customs to simply generate, distribute and allocate the images. Measured the association among digital imaging and privacy fortification, Visual Cryptography and Secret Image Sharing is an inclusive preamble to original security methods. The secret sharing control system is used to guard unauthorized data access and to secure distribution of responsive information. An efficient color image visual cryptic filtering scheme is to improve the image quality on restored original image from visual cryptic shares. The color image visual cryptic filtering scheme presents a deblurring effect on the non-uniform distribution of visual cryptic share pixels. Fourier transformation and texture overlapping is applied to normalize the unevenly transformed share pixels on the original restored image. This in turn improves the quality of restored visual cryptographic image to its optimality. The privacy preservation in visual cryptography plays a major role to provide an efficient secure communication for the users. To address data sharing issues more sensitively, a privacy preservation achieved by using cache-cache mechanism. The cache-cache mechanism maintains a cache inside a cache to preserve the details about the users who shared the secret parts of digital document, which has been splitted in a scheme of visual cryptography. In this work, the binary spanning trees are used to enhance the progress of secure distributed file sharing in visual cryptography. Privacy of file sharing is done with file block id relating to the participant id using binary trees. Group dynamics is handled effectively with distributed key exchange model, based on the principal operation of minimum spanning tree variants. Experimentation carried out with bench mark data sets of real and synthetically generated data sets to estimate the performance of the proposed controlled adaptable distributed file sharing with multiple participants in visual cryptography in terms of group dynamic rate, tree spanning length and privacy overhead.

Visual cryptography (VC) schemes provide a distinguished image encryption technique to protect image security since it can visually decrypt the secret image by superimposing the encrypted shadows. VC schemes for both threshold access structures and general access structures are generally constructed based on the OR operation to minimize the pixel expansion. However, VC schemes with optimal pixel expansion typically have low contrast. Stacking operation OR frequently produces recovered images with poor visual quality and are never able to deliver flawless recovery for secret images. Therefore, we studied XOR-based VC (XVC) schemes that employ linear programming to maximize their contrast. Three schemes for general access structures and three schemes for threshold access structures are designed to maximize their contrast. The proposed schemes’ construction is reduced to a linear programming to maximize the contrast by determining the ideal combinations of basis matrices in terms of primary column matrices and unit matrices, respectively. The comparison study and experimental results demonstrate that the contrast of the previous VC and XVC schemes can be further improved.

Visual Cryptography for General Access Structures

For preserving the security of data there has been tremendous research areas evolved and explored since few years. Cryptography is seen to be the dominant strategy in the information security domain. To differentiate security of multimediadata, visual cryptography is seen as the prominent way for data confidentiality and secrecy of information being distributed. The mechanism of visual cryptography is widely used approach which encrypts the secrete image into the many meaningless share images and decodes by stacking some or all shares by human visual system. There are many methods presented for visual cryptography with their own advantages and disadvantages.. Over the years , in visual cryptography the scope of research mainly focused on developing techniques on grayscale , halftone , color visual cryptography, region incrementing visual cryptography, minimization of pixel expansion , multiple secret sharing and cheating prevention in visual cryptography. Recently new cheating–preventing scheme has been found whichis advantageous over a combined approach of two general VC codebooks. This method resulted into number of advantages such as computation cost is low; multi factor cheating detection is involved etc. However, we identified two research problems such as 1) there is no efficient generic method of generating (k,n) codebooks with minimizing the pixel expansion, 2) it is impractical and time-consuming to stack three or four shares. Therefore in this project our aim is to extend this hybrid codebook based method with goal of overcoming above two listed limitations. We are presenting the efficient approach for codebooks generation with less timing consuming while decryption. Keywords—Contrast,Share,Stacking,Pixel expansion.

With the advent of the widespread use of Internet for communication, there is an increase in exchange of personal secured information via the Internet wherein a large variety of sensitive information is exchanged between the end users which affect the privacy and safety of the data during storage and communication. Visual cryptography, an example of a secret sharing scheme encrypts the secret digital information into a number of shares wherein the decryption is performed by overlaying the shares generated and by utilizing the HVS (Human Visual System). General access structures efficiently hides the data by defining an access structure of qualified sets which only can produce the hidden information. Since no transmission is noise free, quantum neural network is used to extract the original information even when the information is not clearly visible to the human eye. The paper proposes a methodology to conceal multiple secret in a pair of shares and the Q’tron network to improve the security of information systems.

The rapid progress in digital transmission technology has spurred demand for developing a technology that supports monitoring of video transmissions. Automating the picture quality assessment process is in particular demand because it currently depends on subjective assessments by human operators and places a heavy burden on them. The authors therefore propose an objective picture quality measurement method that works without reference pictures. In this proposed method, invisible markers are embedded into original pictures by use of the spread spectrum data hiding method. Since the markers are widely spread over the frequency domain, the degradation caused by MPEG compression can be estimated by detecting the extent of marker degradation. Our method is usable regardless of the kind of picture, bitrate, and number of stages of tandem codec connections. The degradation in picture quality caused by the embedded markers is quite small and not perceivable by the human eye. The proposed method is therefore applicable to a wide range of visual transmission services.

Related to the growth of data sharing on the Internet and the wide - spread use of digital media, multimedia security and copyright protection have become of broad interest. Visual cryptography () is a method of sharing a secret image between a group of participants, where certain groups of participants are defined as qualified and may combine their share of the image to obtain the original, and certain other groups are defined as prohibited, and even if they combine knowledge of their parts, they can’t obtain any information on the secret image. The visual cryptography is one of the techniques which used to transmit the secrete image under the cover picture. Human vision systems are connected to visual cryptography. The black and white image was originally used as a hidden image. In order to achieve the owner’s copy right security based on visual cryptography, a watermarking algorithm is presented. We suggest an approach in this paper to hide multiple images in video by meaningful shares using one binary share. With a common share, which we refer to as a smart key, we can decrypt several images simultaneously. Depending on a given share, the smart key decrypts several hidden images. The smart key is printed on transparency and the shares are involved in video and decryption is performed by physically superimposing the transparency on the video. Using binary, grayscale, and color images, we test the proposed method.

Due to light scattering by air particles, images taken under bad lighting conditions (such as haze, fog, mist, or smog) have a reduced level of visibility. One blurry image can be made visible again using single image dehazing techniques. Due to the ill-posedness of the Single image dehazing problem, it is difficult to solve. Even though, the Dark channel prior (DCP) has been the most prevalent method for image dehazing algorithms, but it suffers from huge computational time and picture quality. The accurate transmission map estimation is one of the best preferred ways to achieve the least computational time and high picture quality in DCP. Hence, this work is focused on constructing transmission map of a hazy image based on feed forward artificial neural network. The recommended method uses a feed forward ANN to conduct the transmission map straight from the minimum channel and a normalizing procedure to increase the re-covered image information. With a training set of eighty images, the network is trained by means of mean square error (MSE). The proposed method utilizing peak signal to noise ratio (PSNR) and structural similarity (SSIM) index measures are used to assess the restoration quality. The investigational conclusions have demonstrated that, the suggested method outperforms the dehazing of an input image without degrading visible quality (PSNR = 69.16, SSIM index = 0.8913). In addition, the proposed method is suited for real-time applications given the average computing time it achieves is 1.03 s.

Peak signal-to-noise ratio (PSNR) is commonly used as a measure for the quality of the reconstructed picture where the original picture is used as reference data. Since the original picture is not available in the video decoder, the receiver cannot evaluate the quality of the reconstructed image from the viewpoint of PSNR. Proposed is an efficient method to estimate PSNR using the statistical distribution of the integer transform coefficient in an H.264 decoder.

Conventional visual secret sharing schemes generate noise-like random pixels on shares to hide secret images. It suffers a management problem, because of which dealers cannot visually identify each share. This problem is solved by the extended visual cryptography scheme (EVCS), which adds a meaningful cover image in each share. However, the previous approaches involving the EVCS for general access structures suffer from a pixel expansion problem. In addition, the visual cryptography (VC)-based approach needs a sophisticated codebook design for various schemes. In this paper, we propose a general approach to solve the above- mentioned problems; the approach can be used for binary secret images in noncomputer-aided decryption environments. The pro- posed approach consists of two phases. In the first phase, based on a given access structure, we construct meaningless shares using an optimization technique and the construction for conventional VC schemes. In the second phase, cover images are added in each share directly by a stamping algorithm. The experimental results indicate that a solution to the pixel expansion problem of the EVCS for GASs is achieved. Moreover, the display quality of the recovered image is very close to that obtained using conventional VC schemes.

The reconstructed image of the size-invariant visual cryptography (VC) is inevitably accompanied by the loss of secret image information and the degradation of perceptual quality. Here, the halftone technique comes to the forefront since it can realistically simulate the grayscale image from a discrete binary image. Thus, by combining VC sharing with grayscale image halftone technique, this paper proposes a size-invariant VC scheme for grayscale image underpinned by the efficient direct binary search (EDBS) algorithm, in which the multi-pixel encryption VC sharing is adopted into the EDBS halftone process. Through local optimizations and global iterations, the optimal reconstructed image is obtained. To further enhance the contrast of the reconstructed image with limited computational power, the image information is probabilistically extracted according to the inverse mapping in the codebook. It is theoretically proved that the proposed scheme is as secure as the traditional VC, while its effectiveness is validated through experiments and comparative analyses.

The reconstructed image of probabilistic visual cryptography (VC) is inevitably accompanied by the loss of secret image information and degradation of visual quality. Since halftone technique can realistically simulate grayscale continuous tone image with a binary image, in this paper, by combining VC sharing with grayscale image halftone technique, we propose a probabilistic VC scheme for grayscale image using EDBS (Efficient Direct Binary Search) to improve the quality of the reconstructed image. The probabilistic VC sharing is adopted into the EDBS halftone process, and the reconstructed image is taken as the optimization object. Through local optimizations and global iterations, the optimal reconstructed image is finally achieved under the established optimization strategy. Theoretically the proposed scheme possesses the same security strength as the traditional VC and experimentally the comparative analysis verifies the effectiveness of this scheme.

Visual cryptography is a powerful method for securely sharing and protecting visual data by splitting an image into multiple shares. Individual shares do not reveal any information, but when combined, they allow for the reconstruction of the original image. The survey categorizes different approaches based on pixel expansion, complexity, and the quality of the reconstructed image. It focuses specifically on color image encryption, an emerging field of interest because of its use in secure communication, digital media, and medical imaging. The paper provides a comprehensive review of recent advances in color visual cryptography, discussing the latest techniques and challenges in the field. his paper is a systematic review of color visual cryptography techniques. The contribution is threefold: (i) categorizing schemes by pixel expansion, complexity, and reconstruction quality, (ii) critically analyzing limitations and trade-offs, and (iii) identifying open research gaps and future directions.

Robust watermarking scheme for color image based on quaternion-type moment invariants and visual cryptography

The file size and picture quality are factors to be considered for streaming, storage and transmitting videos over networks. This work compares Cinepak, Intel, Microsoft Video and Indeo Codec for video compression. The peak signal to noise ratio is used to compare the quality of such video compressed using AVI codecs. The most widely used objective measurement by developers of video processing systems is Peak Signal-to-Noise Ratio (PSNR). Peak Signal to Noise Ration is measured on a logarithmic scale and depends on the mean squared error (MSE) between an original and an impaired image or video, relative to (2n-1)2. Previous research done regarding assessing of video quality has been mainly by the use of subjective methods, and there is still no standard method for objective assessments. Although it has been considered that compression might not be significant in future as storage and transmission capabilities improve, but at low bandwidths compression makes communication possible.