Wyniki wyszukiwania - BazTech

1

Fine-tuned spot detection on ELISPOT images

Bieniecki W., Gonzalez V.M.M., Grabowski S.

Automatyka / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie

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2009

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T. 13, z. 3/1

781-791

EN

Enzyme linked immunospot assay (ELISPOT) is a powerful technique used for detection and quantification of antigen specific immunological responses at the single cell level, which could have a prognostic value to diagnose the long-term graft outcome (i.e., kidney) and to evaluate the level of immunosuppression therapy needed. Basically, ELISPOT image contains round spots of different color, intensity and size. The image analysis should include accurate measurements of spot properties, like area and color. We propose a new approach to spot detection and measurement on ELISPOT microscope images, combining the Canny operator and a circle-fitting routine that we previously used (in somewhat different context) for that class of images. Good edge detection algorithms, like the Canny one, yield locally accurate spot contour arcs but their drawback is that the found arcs are not connected, i.e., do not constitute full contours. We solved the problem, fitting arcs belonging to the same spot contour. For each arc, a circle to each it belongs was approximated and then circle clus-tering was performed not to produce too many (false) contours.

PL

ELISPOT (enzyme linked immunospot assay) jest metodą pozwalającą na ocenę natężenia odpowiedzi immunologicznej wobec określonych antygenów na poziomie pojedynczych komórek. Badanie tej odpowiedzi pozwala na monitorowanie ryzyka przewlekłego odrzutu przeszczepu (np. nerki) i zastosowania odpowiedniej terapii immunosupresyjnej. Obraz w badaniu ELISPOT zawiera okrągłe plamki różniące się zabarwieniem, wielkością i intensywnością. Celem analizy komputerowej obrazu jest precyzyjny pomiar parametrów plamek, takich jak pole powierzchni i kolor. W pracy zaproponowano nowy algorytm detekcji i określenia konturów plamek łączący operator Canny'ego z procedurą aproksymacji średniokwadratowej okręgiem konturu. Podobna metoda została przez nas sprawdzona w innym kontekście (wykrywanie całkowitego obszaru zainteresowania). Algorytmy detekcji krawędzi (m.in. Canny) dobrze lokalnie oddają fragmenty rozmytych konturów, ale zwykle zwracają łuki, a nie zamknięte krzywe. Rozwiązaliśmy ten problem, dopasowując do siebie łuki należące do tego samego konturu. Dla każdego łuku znajdowane było koło, a następnie w procesie grupowania usuwaliśmy fałszywe (nadmiarowe) kontury.

2

Some FFT-like algorithms for RGB-spectra calculation

Chernov V. M.

Machine Graphics and Vision

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2002

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Vol. 11, No. 2/3

139-151

EN

The paper deals with some new algorithms for "overlapped" calculation of 1D and 2D DFT spectra of a multi-channel sognal. The algorithms' computational complexity is decreased via a fast calculation of an auxiliary transform that takes values in special algebraic structures: the group algebra of a quaternion units group and the algebra associated with integral Hurwitz quaternions.

3

Optimised directional distance filter

Lukac R.

Machine Graphics and Vision

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2002

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Vol. 11, No. 2/3

311-326

EN

In this paper, a new adaptive directional distance filter especially for the impulse noise suppression in color images is provided. The proposed method takes advantage from the optimal filtering situation when only the affected samples are estimated, whereas noisy image points are passed to a filter output without change. For that reason, the proposed method is based on switching between the indentity filter (no smoothing) and the directional distance filter that provides a maximum amount of the smoothing. In order to achieve the most precise control of the proposed method, three center-weighted directional distance filters are utilised to determine a parameter compared with a threshold value. This simple comparison serves as a switching control. After the optimisation of the threshold, it will be shown that the proposed method achieves a significant improvement of the filter performance in comparison with standard vector filter classes for a wide range of impulse noise corruption.

4

A classified vector quantization scheme for color image coding perceptually tuned

Charrier C., Cherifi H.

Image Processing & Communications

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2001

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Vol. 7, no 1-2

17-29

EN

Edges are of fundamental importance in the analysis of images, and of course in the field of image quality. To incorporate the edgy: information as coded by the Human Visual System (HVS) in a vector quantization scheme, we have developed a classification strategy to separate edge vectors from non-edge vectors. This strategy allows the generation of different sets of codewords different size for each kind of vectors. For each one of the "edge" sets, the final size is perceptually tuned. Finally, when an image is encoded, its associated edge map is generated. Then the selection of the appropriate "edge" set is made in respect with the edge amount present in the image. Then the second set of non-edge vectors is performed in order to respect the required compression rate. Statistical measure and psychophysical experiments have been performed to judge the quality of reconstructed images.