The two-dimensional method of Langdon and Rissanen for compression of black and white images is extended to handle the exact lossless compression of grey-wale images. Neighbouring pixel values are used to define conte...
The two-dimensional method of Langdon and Rissanen for compression of black and white images is extended to handle the exact lossless compression of grey-wale images. Neighbouring pixel values are used to define contexts and probabilities associated with these contexts are used to compress the image. The problem of restricting the number of contexts, both to limit the storage requirements and to be able to obtain sufficient data to generate meaningful probabilities, is addressed. Investigations on a variety of images are carried out using the JPEG lossless mode predictors. Results indicate that a one pass arithmetic encoder using restricted contexts can lead to effective lossless image compression algorithms.
In this paper, we present an image watermarking scheme based on discrete wavelet transform and singular value decomposition (SVD) for color images. This scheme embeds the watermark into the luminance (Y) channel of YC...
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ISBN:
(纸本)9780889869264
In this paper, we present an image watermarking scheme based on discrete wavelet transform and singular value decomposition (SVD) for color images. This scheme embeds the watermark into the luminance (Y) channel of YC bCR color space of the host image. The luminance image is decomposed up to four DWT levels. SVD is applied on the HL1-4 and LH1-4sub-bands of each level and pseudo random number (PRN) sequence is added to the singular values of their coefficients to produce what we call modified singular values. To obtain the modified HL and LH coefficients, we take the inverse of the SVD of the modified SVs. Finally, we perform the IDWT on the modified HL & LH coefficients as well as HH and LL coefficients to produce the watermarked Y channel image. Then, the modified luminance, Cb and Cr are combined to get the watermarked color image. Simulation results show that our watermark is robust against high JPEG compression, filtering, Gaussian-noise, resizing and other imageprocessing attacks. In addition, this watermark is not susceptible to any false positive or detection of false reference watermark.
Optical Coherence Tomography (OCT) has become a basic non-invasive tool in diagnosing and following different types of eye diseases. This technique can produce high-resolution cross-sectional images of retinal layers....
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The problem of the reconstruction of binary matrices from their fan-beam projections is investigated here. A fan-beam projection model is implemented and afterwards employed in systematic experiments to determine the ...
The problem of the reconstruction of binary matrices from their fan-beam projections is investigated here. A fan-beam projection model is implemented and afterwards employed in systematic experiments to determine the optimal parameter values for a data acquisition and reconstruction algorithm. The fan-beam model, the reconstruction algorithm which uses the optimization method of Simulated Annealing, the simulation experiments, and the results are then discussed in turn.
Pupillometry is a non-invasive technique that can be used to objectively characterize pathophysiological changes involving the pupillary reex. It is essentially the measurement of the pupil diameter over time. Here, s...
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Pupillometry is a non-invasive technique that can be used to objectively characterize pathophysiological changes involving the pupillary reex. It is essentially the measurement of the pupil diameter over time. Here, specially designed computer algorithms provide fast, reliable and reproducible solutions for the analysis. These methods use a priori information about the shape and color of the pupil. Our study focuses on measuring the diameter and dynamics of the pupils of rats with schizophrenia using videos recorded with a modified digital camera under infrared (IR) illumination. We developed a novel, robust method that measures the size of a pupil even under poor circumstances (noise, blur, reections and occlusions). We compare our results with measurements obtained using manual annotation.
Segmentation is one of the key problems in remote sensing imageprocessing, and a cluster hierarchy is a powerful tool to analyze data on multiple scales. In this paper, we present an optimal hierarchical remote sensi...
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The paper presents a general non-rigid body representation for physically-based modeling of dynamic behaviour of heterogeneous objects and its application in a development of a new heterogeneous morphing technique to ...
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images of the eye ground not only provide an insight to important parts of the visual system but also reflect the general state of health of the entire human body. Automatic retina image analysis is becoming an import...
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Our aim was to estimate the volumes of homogeneous structures whose contrast / intensity was changing with time, using only few (here 4) projections of the structures. Each projection was recorded over a period of tim...
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This paper describes a method to smoothen the surface of a Medical object's 3D model. This method is intended to be used on model that was obtained by a triangulation algorithm, but it also can be used on a model ...
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