Wyniki wyszukiwania - Biblioteka Nauki

1

Combined achromatic and chromatic correction of color images

100%

Lucchese L. , Mitra S. K.

Zeszyty Naukowe. Telekomunikacja i Elektronika / Akademia Techniczno-Rolnicza w Bydgoszczy

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2006

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tom z. 9

25-35

EN

This paper advances a new algorithm for determining the color mapping between two images of the same object or scene taken under different illumination conditions. Yhe proposed algorithm compensates for differences in colors by separately equalizing their achromatic and chromatic components. The eqialization of the 1-D achromatic channel is carried out with a standard technique for gray-level images whereas the equalization of the 2-D chromatic channel is considered as a problem of image warping. This method can also be used to color calibrate a trichromatic sensing device, provided that a color chart is available.

PL

W artykule przedstawiono nowy algorytm służący do określenia odwzo-rowania kolorów pomiędzy dwoma obrazami tego samego obiektu lub sceny, uzyskanymi w różnych warunkach oświetleniowych. Działanie zaproponowa-nego algorytmu oparte jest na zasadzie kompensacji różnic kolorów, co wyko-nuje się niwelując różnice oddzielnie dla składowej achromatycznej i chroma-tycznej. Wyrównanie (niwelacja różnic) w achromatycznym kanale l-D jest dokonywane poprzez wykorzystanie standardowej techniki używanej w przy-padku obrazów czarno-białych, natomiast operacja wyrównania w chroma-tycznym kanale 2-D jest rozpatrywana jako problem deformacji obrazu. Przed-stawiona metoda może być również zastosowana do kalibracji kolorów czujni-ków kolorów, przy założeniu, że referencyjny rozkład kolorów jest znany.

2

A novel method for detecting light source for digital images forensic

80%

Roy A. K. , Mitra S. K. , Agrawal R.

Opto-Electronics Review

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2011

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tom Vol. 19, No. 2

211-218

EN

Manipulation in image has been in practice since centuries. These manipulated images are intended to alter facts - facts of ethics, morality, politics, sex, celebrity or chaos. Image forensic science is used to detect these manipulations in a digital image. There are several standard ways to analyze an image for manipulation. Each one has some limitation. Also very rarely any method tried to capitalize on the way image was taken by the camera. We propose a new method that is based on light and its shade as light and shade are the fundamental input resources that may carry all the information of the image. The proposed method measures the direction of light source and uses the light based technique for identification of any intentional partial manipulation in the said digital image. The method is tested for known manipulated images to correctly identify the light sources. The light source of an image is measured in terms of angle. The experimental results show the robustness of the methodology.

3

Hybrid data gathering scheme in wireless sensor networks

80%

Mitra S. K. , Chakraborty A. , Naskar M. K.

Journal of Applied Computer Science

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2011

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tom Vol. 19, nr 2

73-88

EN

For time-sensitive applications from a remote wireless sensor network, demands to design an efficient routing scheme that can enhance network lifetime and also offer an optimized performance in energy efficiency and reduced delay. In this paper, we propose an improved clustered-hop data gathering scheme which is a amalgamation of clustering and nearest neighborhood selection of the sensor nodes in each hop. The cluster heads and the super leader are altered every round for ensuring an uniformly distributed energy consumption among all the nodes. We have implemented the proposed scheme in nesC and performed simulations in TOSSIM. Successful packet transmission rates have also been analyzed using the interference-model. Compared with the existing popular schemes such as PEGASIS, BINARY, LBEERA and SHORT, our scheme offers an improved "energy delay" performance and has the capability to achieve a very good symmetry among different performance metrics.

4

A study on Partitioned Iterative Function Systems for image compression

80%

Mitra S. K. , Murthy C. A. , Kundu M. K.

Fundamenta Informaticae

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1998

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tom Vol. 34, nr 4

413-428

EN

The technique of image compression using Iterative Function System (IFS) is known as fractal image compression. An extension of IFS theory is called as Partitioned or local Iterative Function System (PIFS) for coding the gray level images. The theory of PIFS appears to be different from that of IFS in the sense of application domain. Assuming the theory of PIFS is the same as that of IFS, several techniques of image compression have been developed. In the present article we have studied the PIFS scheme as a separate one and proposed a mathematical formulation for the existence of its attractor. Moreover the results of a Genetic Algorithm (GA) based PIFS technique is presented. This technique appears to be efficient in the sense of computational cost.

5

A New Probabilistic Approach for Fractal Based Image Compression

70%

Mitra S. K. , Kundu M. K. , Murthy C. A. , Bhattacharya B. B. , Acharya T.

Fundamenta Informaticae

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2008

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tom Vol. 87, nr 3-4

417-433

EN

Approximation of an image by the attractor evolved through iterations of a set of contractive maps is usually known as fractal image compression. The set of maps is called iterated function system (IFS). Several algorithms, with different motivations, have been suggested towards the solution of this problem. But, so far, the theory of IFS with probabilities, in the context of image compression, has not been explored much. In the present article we have proposed a new technique of fractal image compression using the theory of IFS and probabilities. In our proposed algorithm, we have used a multiscaling division of the given image up to a predetermined level or up to that level at which no further division is required. At each level, the maps and the corresponding probabilities are computed using the gray value information contained in that image level and in the image level higher to that level. A fine tuning of the algorithm is still to be done. But, the most interesting part of the proposed technique is its extreme fastness in image encoding. It can be looked upon as one of the solutions to the problem of huge computational cost for obtaining fractal code of images.