Understanding what the problems are in robot-vision architecture, requires a better comparison of major features. But a zoology of vision machines is questioned when, aiming for a well informed architectural feature c...
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Understanding what the problems are in robot-vision architecture, requires a better comparison of major features. But a zoology of vision machines is questioned when, aiming for a well informed architectural feature choice, a rapid presentation of technological trends in the field is proposed. Then an approach closer to physics prompts to a classification from a control point of view: it reveals some duality between operations and communications. A few visual operations are distinguished provided technology is not trailing behind. But emphasis should be put on communication networks, although they do not show any imageprocessing specificity currently, and the conclusion addresses some limits in that respect.< >
We propose codec designs for image browsing. image/video browsing is an important requirement in many multimedia applications. In image browsing, a lower resolution version of the image is first viewed. Upon request, ...
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We propose codec designs for image browsing. image/video browsing is an important requirement in many multimedia applications. In image browsing, a lower resolution version of the image is first viewed. Upon request, the resolution is further enhanced until an acceptable fidelity is obtained. Recently, many new codecs have been designed for image/video compression. However these codecs are not directly applicable for image browsing as they cannot interact with the user. In this paper, we propose a codec design based on Gabor decomposition which is well adapted for image browsing applications. However we note that the generic design can be implemented with any compression algorithm. Gabor decomposition is a promising approach for image browsing. The Gabor basis functions match the human visual profiles and hence result in better subjective quality compared to JPEG. For example, Gabor decomposition does not suffer from the blocking artifacts prevalent in JPEG-DCT. The proposed codec can achieve real-time performance, is simple and modular and hence can be implemented in VLSI.< >
The quality of visualcommunications has greatly improved with HDTV. Due to the advantages of digital communications, and the trend towards it, it is desirable to develop a cost effective digital codec for HDTV signal...
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The quality of visualcommunications has greatly improved with HDTV. Due to the advantages of digital communications, and the trend towards it, it is desirable to develop a cost effective digital codec for HDTV signals. One of the criteria in the transmission of digital signals via satellites is the transmission bandwidth which dictates the transmission costs. Apart from development of good compression schemes, due consideration should also be given to the ease of hardware implementation, which is crucial in deciding factors like processing delay and the level of encoder/decoder complexity. With the above mentioned factors in mind a cost-effective HDTV codec is proposed. Few US organizations have addressed the problem of HDTV distribution via communication satellites. The majority of efforts in the development of an HDTV codec have been aimed at the 100 to 140 Mbits/sec data rate. To facilitate cost effective satellite transmission, the DS3 rate of 45 Mbits/sec, is desirable. The purpose of the present research is to compress the HDTV signals to around 20 Mbits/sec so that 2 HDTV channels can be transmitted through the DS3 rate channel. To achieve this degree of compression a new scheme is proposed. First subband coding is used to decompose the image into different frequency bands. Next motion compensation is applied to the low band, and the resulting interframe difference is discrete cosine transform (DCT) coded. The high bands are also DCT coded. The DCT coefficients of the difference signal of the low band and the DCT coefficients of the high band are then vector quantized.< >
We present a computational model of contour processing that was suggested by neurophysiological recordings from the monkey visual cortex. The model employs convolutions and nonlinear operations, but no feedback loops....
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We present a computational model of contour processing that was suggested by neurophysiological recordings from the monkey visual cortex. The model employs convolutions and nonlinear operations, but no feedback loops. Contours are defined by the local maxima of the responses of a contour operator that sums a representation of contrast borders and a "grouping signal". The grouping consists in convolving a representation of "key points", such as T-junctions, corners, and line ends, with a set of orientation selective kernels, and a nonlinear pairing operation. The grouping scheme is selective according to whether the configuration of key points is consistent with the interpretation of occlusion. The resulting contour representation includes an indicator of figure ground direction. We show: that the model reproduces illusory contours in accurate agreement with perception; and generates representations of occluding contours on images of natural scenes that are more complete and less cluttered by spurious connections of foreground and background than those obtained by conventional edge detection operators.
In this work, we present a technique which suggests the use of symmetry to reduce the redundancy in images. A symmetry-based image segmentation and coding scheme is described. A segmentation technique is analyzed, and...
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ISBN:
(纸本)0819412236
In this work, we present a technique which suggests the use of symmetry to reduce the redundancy in images. A symmetry-based image segmentation and coding scheme is described. A segmentation technique is analyzed, and applied on natural images, performing their efficient partition. In order to find symmetries in regions of any shape, the concept of axes of symmetry is generalized to skeletons of symmetry, dividing the regions into two symmetric subparts by the introduction of the Medial Axis Transformation of the regions. Each subpart of the regions is then linearly predicted with respect to the skeletons. An efficient coding strategy specifying the shape and the luminance of the regions is described. Results on natural images show that the described technique outperforms the more classical second generation image coding methods in terms of visual quality.
Progressive transmission of images based on lapped orthogonal transform (LOT), adaptive classification and human visual sensitivity (HVS) weighting is proposed. HVS weighting for LOT is developed using a general techn...
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ISBN:
(纸本)0780309510
Progressive transmission of images based on lapped orthogonal transform (LOT), adaptive classification and human visual sensitivity (HVS) weighting is proposed. HVS weighting for LOT is developed using a general technique that can be applied to any orthogonal transform. The method is compared with discrete cosine transform (DCT) based progressive image transmission (PIT). It is shown that the LOT based PIT yields subjectively improved images compared to those based on DCT.
The objective of the paper is to present a new object based image coding technique using morphological segmentation. These are the first results of a final objective of proposing a completely new coding/decoding schem...
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ISBN:
(纸本)0819412236
The objective of the paper is to present a new object based image coding technique using morphological segmentation. These are the first results of a final objective of proposing a completely new coding/decoding scheme for storage and transmission applications based on Mathematical Morphology. The paper presents a new object based image coding algorithm that involves three main processing steps: segmentation, coding of contours and coding of the inside. The three fundamental coding steps of our approach work on a multiscale representation of the data. The coding of contours represents the shape and location of the region and is based on techniques relying on chain codes. The coding of inside consists in modeling the gray level function of the image and in filling each region with this model. Orthogonal polynomials are used for inside coding and bit allocation techniques are developed such that efficient compression rates are obtained. Several computer generated images are presented that show good visual results for a variety of different compression ratios. The techniques can also be applied to image sequences. Current research is under way to propose new coding techniques for both the contour and the inside coding using Mathematical Morphology.
In standard DCT coding schemes like MPEG, the sequences compression is achieved by motion compensation, transformation, quantization, and entropy coding. In this paper, we have followed the same path by adapting to th...
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ISBN:
(纸本)0819413690
In standard DCT coding schemes like MPEG, the sequences compression is achieved by motion compensation, transformation, quantization, and entropy coding. In this paper, we have followed the same path by adapting to the image signal the elements of the coding scheme. The motion compensation is achieved by a block-matching method, where the size of the blocks is adapted to the signal. Great attention has been paid to the relevance of the motion field. Combined with the motion compensation, the two fields of each frame are merged, taking into account the measured motion vectors, to compose a pseudo-progressive frame. The encoding is applied to this `motion-compensated progressive' frame. A wavelet decomposition is then applied on each (inter or intra) frame. Such a transform, intrinsically owning linear- phase and perfect reconstruction properties, has been optimized for maximizing a perceptually weighted coding gain. The wavelet coefficients are thereafter vector-quantized, in order to reach the maximum perceptual SNR : frequency weighting is taken into account. The relevance of the measured vector field allows a precise spatio-temporal quantization optimization. The vectors are entropy coded taking into account the remaining inter-band dependence, by an adapted entropy code. Results obtained from 1 Mbit/s to 8 Mbit/s are shown for moving sequences at the conference.
Picture archiving and communication systems (PACS) have to handle a lot of moving or still images services with different resolution levels (HDTV-like, TV-like and lower resolutions), quality requirements (from accept...
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ISBN:
(纸本)0819412236
Picture archiving and communication systems (PACS) have to handle a lot of moving or still images services with different resolution levels (HDTV-like, TV-like and lower resolutions), quality requirements (from acceptable visual quality to lossless) and different priorities. In this paper we present a new system for the integration of hierarchical images transmission in a broadband network based on the DQDB protocol (IEEE 802.6 standard). This system is based on the combination of two new tools. First we have designed a multiresolution/multiquality image coding scheme based on wavelet transforms. The main original feature of the algorithm is that it allows a multiresolution lossless access to images. A greater compression ration is possible at the price of graceful degradations. Secondly, we have implemented an improved priority mechanism in the DQDB protocol. The aim was that, in case of network overload, the emissions lose quality but are always maintained. A simulation of the implementation of such a system for the handling of the communications inside a hospital is also presented.
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