The draft international standard ITU-T H.263 is closely related to the well known and widely used ITU-T Recommendation H.261. However, H.263 does provide the same subjective image quality at less than half the bit-rat...
The draft international standard ITU-T H.263 is closely related to the well known and widely used ITU-T Recommendation H.261. However, H.263 does provide the same subjective image quality at less than half the bit-rate. In this paper we investigate to what extend single enhancements of H.263 contribute to this performance gain, and consider the trade-off quality vs. complexity. Based on typical test sequences, H.263 with its various modes is compared to H.261 on the basis of rate distortion curves at bit-rates up to 128 kbps. At 64 kbps, the performance gain of H.263 in its default mode compared to H.261 is approximately 2 dB. This improvement is achieved with only little increase of complexity, and is mainly due to more accurate motion compensation with half-pel accuracy. Considering the trade-off quality vs. complexity, the combination of the optional coding-modes "Advanced prediction mode" and "PB-frames mode" is a good compromise, resulting in an additional performance gain of 1.5 dB PSNR at 64 kbps. The "Syntax-based arithmetic coding mode" on the other hand, offers only a very small performance gain (0.1 dB at 64 kbps) for its increased computational complexity. Results from profiling an H.263 software codec are presented in order to support complexity considerations of the optional coding-modes.
The authors carry out tests with two readily available automated matching algorithms in their application to (a) Magellan SAR stereo images, and (b) ERS-1 and X-SAR real-simulated images. The match points are examined...
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The authors carry out tests with two readily available automated matching algorithms in their application to (a) Magellan SAR stereo images, and (b) ERS-1 and X-SAR real-simulated images. The match points are examined visually, and an accuracy analysis on Magellan data is performed by comparison with manual measurements.
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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The relationship between the recognition rate of handwritten numerals and the normality of the distribution of their features has been investigated experimentally with a large amount of data in various combinations of...
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The relationship between the recognition rate of handwritten numerals and the normality of the distribution of their features has been investigated experimentally with a large amount of data in various combinations of quantized orientations and regions. The recognition method is based on the histogram of local orientation of contours of each numeral. To obtain a more accurate orientation quantization, the effectiveness of the orientation quantization using the gray-scale gradient has also been investigated. The results show that: (1) to increase the dimensionality of features, it is better to increase the number of quantized orientations, keeping the number of regions small (e.g., 4 x 4 or 5 x 5);(2) in the same dimensionality, the better the normality of a feature distribution, the higher the recognition rate;(3) a quantization of orientations using gray scales is effective for normalizing a feature distribution;and (4) the filter processing in reduction of the number of quantization scales improves the normality and recognition rate. The recognition of handwritten numerals collected from actual posts were carried out by using the gray-scale local-orientation histogram (400 dimensions). A correct recognition rate of 99.18 percent (mean value) has been obtained.
作者：
ROSENBAUM, J[&lowast]Jan Rosenbaum has worked in the imaging industry for 30 years
first as a newspaper photographer and assistant professor of photography then as a camera designer and image quality specialist in the medical and computer graphics industries. He holds a B.F.A. in art from Wayne State University an M.F.A. in photography from Cranbrook Academy of Art an M.S. in imaging and photographic science from Rochester Institute of Technology and an M.S. in management of technology from Polytechnic University of New York. Until recently he was head of the optical and color science group at a division of Agfa-Gevaert.
The medical imaging industry offers an example of what can happen when an industry ignores threats from new technologies and fails to respond to a change in the paradigm upon which it is based. The lessons learned fro...
The medical imaging industry offers an example of what can happen when an industry ignores threats from new technologies and fails to respond to a change in the paradigm upon which it is based. The lessons learned from these basic errors in management may help those in other industries that operate at technology's edge to avoid obsolescence. The company discussed is, or was, real. As of summer, 1993, the last remaining vestige of the company was sold off to a small group of employees and their backers. The number of employees, once 900, is now fewer than 100. Most of them are looking for a way to stay in business.
Possibilities and techniques for the combined use of SAR and high resolution optical satellite imagery are discussed. Differences in imaging geometry and scene illumination complicate the analysis of multi-sensor data...
Precise geometric description of river sediment trails in the sea may assist in a better understanding of the complex processes happening in this type of environment. By means of stereo restitution of a Space Shuttle ...
Precise geometric description of river sediment trails in the sea may assist in a better understanding of the complex processes happening in this type of environment. By means of stereo restitution of a Space Shuttle Large Format Camera photo pair it could be shown that a three-dimensional survey of the margins of individual sediment trails is possible. It turns out, however, that the positioning of the measuring mark is not always easy, and that this type of plotting needs a well-experienced operator. The bathymetric information obtained is brought in relation to sedimentological aspects.
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