Automated detection of subtle changes in sequential images requires development of procedures that ensure true subtraction of two images by proper registration and normalization of illumination. The difference image c...
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Automated detection of subtle changes in sequential images requires development of procedures that ensure true subtraction of two images by proper registration and normalization of illumination. The difference image can then be further processed to analyze the spectral components and the gray level variations. An innovative and generalized approach to accurate image subtraction incorporating illumination normalization and correction for translation, rotation, and scale difference in two sequential images is considered. The entire procedure yielding true image subtraction has been implemented in a PC-based imageprocessing system and can be executed by menu-driven operations. The effectiveness of this approach is illustrated through subtraction of registered sequential fundus images and analysis of the spectral and gray-level variations of the difference images.
Probability of detection and postdetection integration efficiency are formulated and calculated for pulses that are partially correlated. For high probabilities of detection, substantial gain may be obtained for a coh...
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Probability of detection and postdetection integration efficiency are formulated and calculated for pulses that are partially correlated. For high probabilities of detection, substantial gain may be obtained for a coherent idar system applied to diffuse target returns when a small number of pulses are integrated.
We report on the operation of the double phase-conjugate mirror (DPCM). Two inputs to opposite sides of a photorefractive barium titanate crystal, which may carry different spatial images, are shown to pump the same f...
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We report on the operation of the double phase-conjugate mirror (DPCM). Two inputs to opposite sides of a photorefractive barium titanate crystal, which may carry different spatial images, are shown to pump the same four-wave mixing process mutually and are self-refracted without any external or internal crystal surface. This results in the phase-conjugate reproduction of the two images simultaneously. This device is analyzed theoretically, and applications in imageprocessing, interferometry, and rotation sensing are discussed. We also demonstrate the operation of a ring laser, using the DPCM, as well as a photorefractive resonator with two facing DPCM’s that can support spatial information in its oscillations.
This paper explores the application of a parallel computational model, the associative network, to problems in low-level machine vision. A formal description of the associative network model is presented. Then associa...
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This paper explores the application of a parallel computational model, the associative network, to problems in low-level machine vision. A formal description of the associative network model is presented. Then associative networks are designed for performing Boolean functions, edge detection, and the Hough transform. Associative networks feature very flexible processor interconnections. The flexible processor interconnections allow for parallelism in the algorithm design beyond what is feasible in other parallel computational models. This work demonstrates that imageprocessing transformations, often too slow to be practical on a sequential machine, can be executed rapidly with associative networks.
LISPIX is an imageprocessing and analysis system consisting of a sub-system of imageprocessing commands implemented in FORTRAN and a collection of analysis algorithms implemented in LISP. Examples are given of using...
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LISPIX is an imageprocessing and analysis system consisting of a sub-system of imageprocessing commands implemented in FORTRAN and a collection of analysis algorithms implemented in LISP. Examples are given of using the system for microanalysis applications. The processing commands are useful alone for simple tasks. For analysis applications, the LISP programming environment, for which the processing commands are designed, allows rapid development of algorithms and a convenient way to use them. Appendices contain definitions of the most useful commands as well as examples of the LISP algorithms.
An asynchronous method of implementing the digital multiplication by analog convolution algorithm is presented. The mixed binary output is formed in one switching time regardless of the number of bits in the word. Nov...
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An asynchronous method of implementing the digital multiplication by analog convolution algorithm is presented. The mixed binary output is formed in one switching time regardless of the number of bits in the word. Novel circuitry that logarithmically reduces the number of shift and add levels is shown.
Natural background was recorded in the 8–12- μ mband using an airborne IR camera. The results were analyzed, and the statisticaland spatial features of the radiance in this band were found. The statisticaldistributi...
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Natural background was recorded in the 8–12- μ mband using an airborne IR camera. The results were analyzed, and the statisticaland spatial features of the radiance in this band were found. The statisticaldistribution approaches the normal distribution inside the two standarddeviation regions but deviates slightly outside. The spatial autocorrelationfunction fits to a high degree a 2-D exponent.
A means of selecting the optimum x-ray wavelength for an x-ray tomographic imaging system is proposed. In the evaluation, both the detection process and the image reconstruction algorithm are taken into account. The o...
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A means of selecting the optimum x-ray wavelength for an x-ray tomographic imaging system is proposed. In the evaluation, both the detection process and the image reconstruction algorithm are taken into account. The optimum wavelength is selected so that the stability of the reconstructed images is maximized. A concrete means of getting the optimum wavelength in connection with the detectable projections is also shown.
A modified method of fabrication of sandwich holographic interferograms coupled with a digital evaluation technique has yielded ultrahigh resolution of surface deformation. The computer processing technique permits bo...
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A modified method of fabrication of sandwich holographic interferograms coupled with a digital evaluation technique has yielded ultrahigh resolution of surface deformation. The computer processing technique permits both the subfringe resolution and automatic fringe order determination (i.e., discrimination between depression and elevation of the deformed object surface). The technique presented here requires neither the interactive processing nor the fringe interpolation required by other techniques. Such processes are inaccurate, especially when there is a small number of interference fringes. With this type of analysis, sandwich interferometry is capable of fast, simple, ultrahigh resolution of surface deformation.
A method for simulating sea surface images obtained by forward-looking infrared (FLIR) sensors in the 8–12- μ m band, which can be readily implemented on a computer, has been developed. The model consists of a botto...
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A method for simulating sea surface images obtained by forward-looking infrared (FLIR) sensors in the 8–12- μ m band, which can be readily implemented on a computer, has been developed. The model consists of a bottom-up process based on oceanographic models of sea waves and radiometric properties of sky and sea. The clutter which is generated by sea surface roughness and nonuniformity of sky radiation has been found to be a Gaussian homogeneous random process, under reasonable assumptions. The variance of this process as well as its spatial correlation has been investigated. The value of the method as a synthetic image generator and the application of the results to FLIR imageprocessing are discussed.
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