A dual channel Airborne Microwave Radiometric imaging system (AMRI) was designed and constructed for regional environment mapping. the system operates at 35GHz, which collects radiation at horizontal and vertical pola...
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A dual channel Airborne Microwave Radiometric imaging system (AMRI) was designed and constructed for regional environment mapping. the system operates at 35GHz, which collects radiation at horizontal and vertical polarized channels. It runs at mechanical conical scanning with 45° incidence angle. two Cassegrain antennas with 1.5° (3dB) beamwidth scan the scene alternately and two pseudo-color images of two channels are displayed on the screen of PC in real time. Simultaneously all parameters of flight and radiometric data are stored in hard disk for post-processing. the sensitivity of the radiometer Δt = 0.16K (integration time τ = 1s). A new displaying method, unequal size element arc displaying method, is used in image displaying. Several experiments on mobile tower were carried out and the images demonstrate thatthe AMRI is available to work steadily and accurately.
Recently, a variety of imaging devices are being used to representelectronic color images. the reproduced color, however, is different from the original color because of the difference of producible colors on the dev...
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Recently, a variety of imaging devices are being used to representelectronic color images. the reproduced color, however, is different from the original color because of the difference of producible colors on the devices. the range of producible colors offered by a device is referred to as its gamut. In this paper, a gamut-mapping algorithm (GMA) is proposed that can maintain device-independent color. Categorized as a parametric GMA, this algorithm utilizes variable anchor points (a center of gravity on the lightness axis) to both reduce a sudden color change on the gamut boundary of the printer and to maintain a uniform color change during the mapping process. Accordingly, the proposed algorithm can reproduce high quality images with low-cost color devices.
this paper describes a perceptual measure for still image compression systems. Considering the factthatthe conventional PSNR cannot sufficiently reflectthe result of subjective assessment, other quality measures ha...
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this paper describes a perceptual measure for still image compression systems. Considering the factthatthe conventional PSNR cannot sufficiently reflectthe result of subjective assessment, other quality measures have been considered to design the variable bit-rate coders. Indeed, there is a growing interest for perceptual quality measure. Some works have been carried out in the field of still picture quality evaluation while trying to introduce some properties of the human visual system. In the recent literature there are roughly three properties that are identified as being useful. the best known, and generally most widely used properly, is the modulation transfer function (MtF) of the human visual system (HVS). the other two properties can be described as luminance masking and texture masking. A large number of image quality measures of this kind have been developed, with different degrees of success. In previous works, we provided a rigorous evaluation of metrics which take into account artifacts generated by compression method like JPEG. the results show thatthese metrics are highly correlated with the subjective quality grading but also depend on the complexity of the images under study. then, we propose a new perceptual metric for still image compression based on multiresolution decomposition. It allows characterize imagetexture, better takes into account masking effect and don't depend on compression method.
Blue noise dither halftoning methods have been found to produce images with pleasing visual characteristics. Results similar to those generated by error-diffusion algorithms can be obtained using an imageprocessing a...
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Blue noise dither halftoning methods have been found to produce images with pleasing visual characteristics. Results similar to those generated by error-diffusion algorithms can be obtained using an imageprocessing algorithm that is comparatively much simpler to implement. the blue noise dither matrix design method used in this study is based on minimization of a visual cost function. the visual cost function combines the frequency spectrum of the spatial modulation of the halftone pattern with the frequency response of the human visual system to define a visual cost metric. A sequential optimization approach using stochastic annealing is used. the design parameters associated with this method are viewing distance, print resolution, size of the dither matrix, and form of visual cost function. the effect of these design parameters on the resulting image quality of halftone prints is the topic of this paper. Blue noise dither matrices were designed using a variety of viewing distances for a 200 dpi printing system. testimages were generated and the prints were visually examined for texture artifacts. A preferred viewing distance parameter value of 10-20 inches was indicated. the effect of the dither matrix size and the form of the visual cost function will be reported sometime in future.
the growth of digital video has given rise to a need for computational methods for evaluating the visual quality of digital video. We have developed a new digital video quality metric, which we call DVQ (Digital Video...
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the growth of digital video has given rise to a need for computational methods for evaluating the visual quality of digital video. We have developed a new digital video quality metric, which we call DVQ (Digital Video Quality). Here we provide a brief description of the metric, and give a preliminary report on its performance. DVQ accepts a pair of digital video sequences, and computes a measure of the magnitude of the visible difference between them. the metric is based on the Discrete Cosine transform. It incorporates aspects of early visual processing, including light adaptation, luminance and chromatic channels, spatial and temporal filtering, spatial frequency channels, contrast masking, and probability summation. It also includes primitive dynamics of light adaptation and contrast masking. We have applied the metric to digital video sequences corrupted by various typical compression artifacts, and compared the results to quality ratings made by human observers.
In order to establish a synergy between the compression scheme and the intended processing of the compressed image, we develop a family of compression algorithmsthat can adaptto the specialized requirements imposed ...
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In order to establish a synergy between the compression scheme and the intended processing of the compressed image, we develop a family of compression algorithmsthat can adaptto the specialized requirements imposed by the application. the focus of this work is on wavelet-based compression for still images. A family of eight compression schemes is proposed to address specialized multimedia requirements such as (i) partial evaluation of wavelet coefficients, (ii) asymptotic losslessness of the algorithms, (iii) tree-structure in the selected coefficients, and (iv) optimization of either energy compaction or coefficient retention. Experimental results, including fraction of coefficients evaluated, rate-distortion performance, and coefficient retention are presented. (C) 1998 spie and IS&t. [S1017-9909(98)00503-0].
We presentalgorithms for automatic image annotation and retrieval based on color, shape, texture, and any combination of two or more of these features. Pixel- or region (object)-based color. region-based shape;and bl...
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We presentalgorithms for automatic image annotation and retrieval based on color, shape, texture, and any combination of two or more of these features. Pixel- or region (object)-based color. region-based shape;and block- or region-based texture features have been considered. Automatic region selection has been accomplished by integrating color and spatial edge features. Color, shape, and texture indexing may be knowledge based (using appropriate training sets) or by example. the multifeature integration algorithms are designed to: (i) offer the user a wide range of options and flexibilities in order to enhance the outcome of the search and retrieval operations, and (ii) provide a compromise between accuracy and computational complexity, and vice versa. We demonstrate the performance of the proposed algorithms on a variety of images. (C) 1998 spie and IS&t. [S1017-9909(98)02603-8].
An emerging trend in the banking industry is to digitize checks for storage and transmission. An immediate requirement for efficient storage and transmission is check image compression. General purpose compression alg...
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An emerging trend in the banking industry is to digitize checks for storage and transmission. An immediate requirement for efficient storage and transmission is check image compression. General purpose compression algorithms such as JPEG and wavelet-based methods produce annoying ringing or blocking artifacts at high compression ratios, in this paper, a layered approach to check image compression is proposed in which a check image is represented in several layers. the first layer describes the foreground map;the second layer specifies the gray levels of foreground pixels;the third layer is a lossy representation of the background image;and the fourth layer describes the error between the original and the reconstructed image of the firstthree layers. the layered coding approach produces images of better quality than traditional JPEG and wavelet coding methods, especially in the foreground, i.e., the text and graphics, in addition, this approach allows progressive retrieval or transmission of differentimage layers. (C) 1998 spie and IS&t. [S1017-9909(98)01403-2].
In this article a method to classify digital images into three categories based on a provisional analysis of the image content and a subsequent compression with the help of a suitable algorithm of compression is propo...
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ISBN:
(纸本)0819428612
In this article a method to classify digital images into three categories based on a provisional analysis of the image content and a subsequent compression with the help of a suitable algorithm of compression is proposed. to classify the images two parameters are used. the first parameter carries the frequency information aboutthe image. It represents the mean of the absolute amplitude of the Wavelet coefficients in the high frequency parts of the spectrum. the second parameter is an indicator concerning information aboutthe structure of the image. the second parameter is constituted through the entropy of the length of the segments in one line and the entropy of the length of the segments in one column. In this article the results for the check of those classification rules for DICOM images are given as a confirmation of the effectivness of the method proposed. the implementation of the image classification algorithm an the compression algorithms in the modelling process is performed in JAVA.
the exchange of visual information in heterogeneous networks requires image compression algorithmsthat provide high quality images at several spatial resolutions and bit rates. Scalable coding provides images at seve...
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the exchange of visual information in heterogeneous networks requires image compression algorithmsthat provide high quality images at several spatial resolutions and bit rates. Scalable coding provides images at several resolutions and bit rates, while perceptual coding incorporates human visual system characteristics. this paper presents an image compression algorithm that provides both scalable and perceptual coding to produce an embedded stream suitable for transmission over packet networks. Scalable and perceptual coding are combined through intraband coding of perceptually significantimage regions. images are segmented into smooth, edge, and detailed regions, and these regions are then independently intraband coded and included in the stream in decreasing order of visual importance with respectto both region type and scale. Visual importance is based on the results of two psychophysical studies analyzing sensitivity to noise in differentimage regions and their roles in recognition. Locally adaptive quantization, based on study results, is also included in the compression algorithm. the resulting embedded stream provides spatial sealability and region-selective coding and performs well in the presence of packet loss. (C) 1998 spie and IS&t. [S1017-9909(98)00403-6].
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