Perceptual hashing is conventionally used for content identification and authentication. In this work, we explore a new application of image hashing techniques. By comparing the hash values of original images and their compressed versions, we are able to estimate the distortion level. A particular image hash algorithm is proposed for this application. The distortion level is measured by the sig...

The goal of image steganography is to embed information in a cover image using modifications that are undetectable. In actual practice, however, most techniques produce stego images that are perceptually identical to the cover images but exhibit statistical irregularities that distinguish them from cover images. Statistical steganalysis exploits these irregularities in order to provide the best...

This paper presents a discrete cosine transform (DCT)-based locally adaptive perceptual image coder, which discriminates between image components based on their perceptual relevance for achieving increased performance in terms of quality and bit rate. The new coder uses a locally adaptive perceptual quantization scheme based on a tractable perceptual distortion metric. Our strategy is to exploi...

Bronchoscopy is a commonly used clinical tool that provides a direct image of the bronchial lumen. However, bronchoscopy has seen little use as a quantitative measurement tool, mainly because of the wide-angle lens which distorts the image. The present authors have tested the ability of numerical algorithms and commercial software to correct for this distortion. Test objects of known size were ...

It remains a challenge to simultaneously remove geometric distortion and space-time-varying blur in frames captured through a turbulent atmospheric medium. To solve, or at least reduce these effects, we propose a new scheme to recover a latent image from observed frames by integrating a new variational model and distortion-driven spatialtemporal kernel regression. The proposed scheme first cons...

INTRODUCTION AND OBJECTIVE Disadvantages associated with direct high b-value measurements may be avoided with use of computed diffusion-weighted imaging (cDWI). The purpose of this study is to assess the diagnostic performance of cDWI image sets calculated for high b-values of 1500, 2000, and 3000 s/mm(2). MATERIALS AND METHODS Twenty-eight patients who underwent multiparametric MRI of the pr...

Most wavelet-based image coders fail to model the joint coherent behavior of wavelet coefficients near edges. Wedgelets offer a convenient parameterization for the edges in an image, but they have yet to yield a viable compression algorithm. In this paper, we propose an extension of the zerotree-based Space-Frequency Quantization (SFQ) algorithm by adding a wedgelet symbol to its tree-pruning o...

Accurate biometric system for authentication is the need of the hour in today’s scenario. In face spoofing attack a person tries to pretend to be a valid user by using photo or video of an authorized person and gets illegitimate access. Hence it is essential to develop a robust and authentic face spoof detection system in order to protect the privacy about the person. Centre of attraction of th...

The paper presented a reversible image authentication scheme for VQ images using codebook clustering. The proposed method not only locates the alterations of VQ images but also recover the indexes of VQ image without any distortion from the marked VQ indexes after the hidden authentication bits have been extracted. The method uses the codebook clustering to generate four fixed-size small codebo...

In this paper, we develop a novel method for camera calibration and correction. The novel method first employs a rigidity constraint from the rigid rotation matrix and the radial alignment constraint from the pin-hole camera model to estimate both camera intrinsic and extrinsic parameters with a closed-form solution without considering the camera distortion. Then the well-known Levernburg-Marqu...