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.
the performance assessment of the EO-1 Advanced Land imager (ALI) requires software for processing data collected during sensor integration and test (I&t), ground calibration, and on-orbit operations. this paper d...
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ISBN:
(纸本)0819432369
the performance assessment of the EO-1 Advanced Land imager (ALI) requires software for processing data collected during sensor integration and test (I&t), ground calibration, and on-orbit operations. this paper describes the software developed for performance assessmentprocessing and analysis of data collected on the ground during ALI (I&t) and ground calibration. this involves various characterizations and calibrations of the ALI, including functional test, focus, MtF, radiometric response, spectral response, functional image reconstruction, and internal calibration lamp data processing. processing examples are given, including results. Also, each section describes the use of this software to supportthe analysis of data collected on-orbit during mission operations, as well as the types of data to be collected and processed. the interface between MIt Lincoln Laboratory and the EO-1 Mission Operations Center at NASA Goddard Space Flight Center is also described.
the classical approach in vision research - the derivation of basically linear filter models from experiments with simple artificial test stimuli - is currently undergoing a major revision. Instead of trying to keep t...
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ISBN:
(纸本)081943115X
the classical approach in vision research - the derivation of basically linear filter models from experiments with simple artificial test stimuli - is currently undergoing a major revision. Instead of trying to keep the dirty environment out of our clean labs we put it now right into the focus of scientific exploration. the new approach has a close relation to basic engineering strategies for electronicimageprocessing since its major concept is the exploitation of the statistical redundancies of the environment by appropriate neural transformations. the standard engineering methods are not sufficient, however. Even a basic biological feature like orientation selectivity requires the consideration of higher-order statistics, like cumulants or polyspectra. Furthermore, there exists an abundance of nonlinear phenomena in biological vision, for example the phase-invariance of complex cells, cortical gain control, or end-stopping, which make it necessary to consider unconventional modeling approaches like differential geometry or Volterra-Wiener systems. By use of such methods we cannot only gain a deeper understanding of the adaptation of the visual system to the complex natural environment, but we can also make the biological system an inspiring source for the design of novel strategies in electronicimageprocessing.
the U. S. Army Research Laboratory (ARL), as part of its mission-funded applied research program, has been evaluating the utility of a low-frequency, ultra-wideband (UWB) imaging radar to detecttactical vehicles conc...
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ISBN:
(纸本)0819431788
the U. S. Army Research Laboratory (ARL), as part of its mission-funded applied research program, has been evaluating the utility of a low-frequency, ultra-wideband (UWB) imaging radar to detecttactical vehicles concealed by foliage. Measurement programs conducted at Aberdeen Proving Ground and elsewhere have yielded a significant and unique database of extremely wideband and (in some cases) fully polarimetric data, Complementary efforts have been underway to develop high-performance algorithms as well as data visualization and assessmenttools to generate very high-quality, low-artifact-level imagery for use in target detection and exploitation studies. Prior reports have concentrated on discussions of emerging detection concepts. Key strategy has been to exploit frequency-dependent scattering to identify and locate likely targets-particularly the application of a "spatial affinity" technique between detection lists separately generated at VHF frequencies versus UHF. the utility of this approach is now being evaluated more broadly by the UWB radar community. A large quantity of appropriate data has been measured by two separate airborne radars-a VHF radar (Coherent Ali RAdio BAnd Sensing (CARABAS)) [1,2] and a UHF radar (the P-3 radar) [3,4]. In support of Defense Advanced Research Project Agency's (DARPA) national-scope initiative in foliage penetration, ARL is using tools and algorithms developed as part of our mission program to perform image formation and evaluate various spatial affinity concepts on this freshly measured data. the reader will find this paper is organized into three complementary sections. First, we define the research objectives ARL and other defense organizations share. We then report in detail on the signal processing/image formation techniques developed as part of our mission program. We conclude with a discusssion on the use of these algorithms and tools with the emerging data from major defense-wide collections. imaging concepts are disc
Visual telepresence systems which utilise virtual reality style helmet mounted displays have a number of limitations. the geometry of the camera positions and of the displays is fixed and is most suitable only for vie...
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Visual telepresence systems which utilise virtual reality style helmet mounted displays have a number of limitations. the geometry of the camera positions and of the displays is fixed and is most suitable only for viewing elements of a scene at a particular distance. In such a system, the operator's ability to gaze around without use of head movement is severely limited. A trade off must be made between a poor viewing resolution or a narrow width of viewing field. to address these limitations a prototype system where the geometry of the displays and cameras is dynamically controlled by the eye movement of the operator has been developed. this paper explores the reasons why it is necessary to actively adjust both the display system and the cameras and furthermore justifies the use of mechanical adjustment of the displays as an alternative to adjustment by electronic or imageprocessing methods. the electronic and mechanical design is described including optical arrangements and control algorithms. An assessment of the performance of the system against a fixed camera/display system when operators are assigned basic tasks involving depth and distance/size perception. the sensitivity to variations in transient performance of the display and camera vergence is also assessed.
We have developed a focused-procedure based upon a collection of imageprocessingalgorithmsthat serve to identify regions-of-interest, ROIs, over a digital image. the loci of these ROIs are quantitatively compared w...
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We have developed a focused-procedure based upon a collection of imageprocessingalgorithmsthat serve to identify regions-of-interest, ROIs, over a digital image. the loci of these ROIs are quantitatively compared with ROIs identified by human eye fixations or glimpses while subjects were looking atthe same digital images. the focused-procedure is applied to adjust and adaptthe compression ratio over a digital image: - high resolution and poor compression for ROIs;low resolution and strong compression for the major expanse of the entire image. In this way, an overall high compression ratio can be achieved, while atthe same time preserving, important visual information within particularly relevant regions of the image. We have bundled the focused-procedure with JPEG, so thatthe JPEG version allows the result of the compression to be formatted into a file compatible for standard JPEG decoding. thus, once the image has been compressed, it can be read without difficulty.
Error diffusion dithering is a technique that is used to represent a grayscale image on a printer, a computer monitor or other bi-level displays. For a number of years it was believed that error diffusion algorithms c...
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Error diffusion dithering is a technique that is used to represent a grayscale image on a printer, a computer monitor or other bi-level displays. For a number of years it was believed that error diffusion algorithms can not be parallelized. On this paper we present a simple error-diffusion parallel algorithm that can be easily implemented on parallel computers that contain linear arrays of processing elements. It can also be implemented easily on specialized hardware. One of the advantages of our algorithm is its low implementation cost, its scalability, and its ability to benefit from standard fault-tolerance techniques.
In an electronic color image capturing device using a single CCD or CMOS sensor, the color information is usually acquired into three sub-sampled color planes such as Red (R), Green (G) and Blue (B). Full resolution c...
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In an electronic color image capturing device using a single CCD or CMOS sensor, the color information is usually acquired into three sub-sampled color planes such as Red (R), Green (G) and Blue (B). Full resolution color is subsequently generated from this sub-sampled image using a suitable 'Color Interpolation' methodology. the color accuracy and appearance of the image is significantly affected by the color interpolation algorithm used to generate the full-resolution color image. In this paper, we present a new block matching based algorithm for color interpolation. the computational complexity of this algorithm is very low and hence suitable for real-time implementation in a portable image capture device e.g. a digital camera. the proposed algorithm produces the similar or better quality color images compared to most of the known color interpolation algorithms in the literature. We have presented results of comparison of the performance of the proposed algorithm with median interpolation and bilinear interpolation which are commonly used in practice.
A distortion metric for color video sequences is introduced. the metric is based on a contrast gain control model of the human visual system that incorporates spatial and temporal aspects of vision as well as color pe...
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A distortion metric for color video sequences is introduced. the metric is based on a contrast gain control model of the human visual system that incorporates spatial and temporal aspects of vision as well as color perception. the model achieves a close fitto contrast sensitivity and contrast masking data from several different psychophysical experiments for both luminance and color stimuli. As an illustration, the metric is used to assess the quality of MPEG-coded sequences.
In recent years computer performance has been improving so rapidly that hardware-in-the-loop simulation by using computer generated images (CGI-HWIL simulation) has come to play the great role in developing and evalua...
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ISBN:
(纸本)0819431710
In recent years computer performance has been improving so rapidly that hardware-in-the-loop simulation by using computer generated images (CGI-HWIL simulation) has come to play the great role in developing and evaluating many kinds of imaging missile systems. Generally speaking, there are two principle methods in CGI-HWIL simulation. One is a method using scene projector for in-band seeker under test, and the other is a method injecting image directly into missile signal processing unit beyond seeker sensor. In japan, the latter is generally used as an effective method of CGI-HWIL simulation to develop and evaluate missile systems. that is because the former can do nothing but depend on import for the scene projector, so there are a lot of disadvantageous points in respects of cost and maintenance. In our company, the former composed by low cost commercial off-the-shelf (COtS) scene generator also has been used to research image homing missile systems. there are two special features in the CGI-HWIL simulation method. One is how to emulate the seeker optics and electronics characteristics, and the other is the technique how to compensate the system latency caused by scene generation components. these special techniques allow us to keep the stability of seeker tracking loop, and to achieve real-time CGI-HWIL simulation effectively with low cost scene generator. First of all, the outline of the CGI-HWIL simulation method is shown. Next, problem in real-time simulation is described, and atthe end how the problem is solved to achieve real-time simulation is explained.
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