Motion-compensated coding, which exploits the temporal redundancies in the moving images, is one of the most popular techniques currently used. Recently, a variable block size (VBS) motion estimation technique has bee...
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Motion-compensated coding, which exploits the temporal redundancies in the moving images, is one of the most popular techniques currently used. Recently, a variable block size (VBS) motion estimation technique has been proposed to improve the performance of the motion-compensated transform coding (MCTC). This technique allows larger blocks to be used when smaller blocks provide little gain, saving the bit rates especially for areas containing more complex motion. However, there have been few efforts to investigate an efficient VBS motion structure for reducing the motion vector coding rates further. Hence, a new VBS motion estimation technique based on a hierarchical structure is proposed that improves the motion vector encoding efficiency and reduces the number of motion vectors to be transmitted as well. Specifically, the gain/cost motion estimation technique with the selective motion prediction is utilized for the topmost level motion vector search, exploiting the redundancies among the neighboring motion vectors. Also, a restricted search with respect to the topmost level motion vector enables more flexible and efficient motion vector encoding for the remaining lower level blocks. Intensive simulations on several moving image sequences show that the MCTC employing the VBS motion estimation provides a performance improvement of 0.7 to 1.0 dB, in terms of peak SNR, compared with the fixed block size motion estimation.
This paper describes the coding methods of the motion vector in the block matching algorithm (BMA). The six entropy coding methods are applied to the original motion vector or to the smoothed motion vector, which is o...
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This paper describes the coding methods of the motion vector in the block matching algorithm (BMA). The six entropy coding methods are applied to the original motion vector or to the smoothed motion vector, which is obtained by considering neighboring motion vectors. Here to increase the coding efficiency of the motion vector, we propose the conditional transmission of the smoothed motion vector by considering the corresponding prediction error. In the proposed coding method, we transmit the image by using entropy coding of the smoothed motion vector and DCT coding of the prediction error for various threshold values. The computer simulation shows that by using the proposed conditional transmission method of the smoothed motion vector, we can compress the motion vector efficiently with a slight degradation in the reconstructed image. Dieser Beitrag beschreibt Verfahren zur Kodierung eines Bewegungsvektors im sogenannten block-matching-algorithmus (BMA). Eine Entropie-Kodierung kann auf den ursprünglichen Bewegungsvektor angewandt werden oder auf eine geglättete Version davon, die man bei Berücksichtigung benachbarter Bewegungsvektoren erhält. Zur Steigerung der Wirksamkeit der Bewegungsvektor-Kodierung schlagen wir die Übertragung des geglätteten Vektors unter bestimmten Bedingungen vor, welche die Betrachtung des entspechenden Vorhersagefehlers betreffen. In der vorgeschlagenen Kodiermethode übertragen wir das Bild, indem wir eine Entropie-Kodierung des geglätteten Bewegungsvektors vornehmen und den Vorhersagefehler nach einer DCT für verschiedene Schwellwerte kodieren. Rechnersimulationen zeigen, daß das vorgeschlagene Verfahren zu einer effizienten Kompression des Bewegungsvektors bei geringfügiger Beeinträchtigung des rekonstruierten Bildes führt. Ce texte décrit les méthodes de codage d'un vecteur de mouvement dans le cas d'utilisation de l'algorithme d'appariement de blocs (en anglais block matching algorithm (BMA)). Les six méthodes de codage par entropie ont
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