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Showing papers on "Pixel published in 1972"


Journal ArticleDOI
TL;DR: Current research programs based on the processing of side-looking radar imagery show that spatial alignment of the various parts of the image must be highly accurate if noise in the difference picture is to be reduced to acceptably low levels.
Abstract: The problem of change detection presents itself for imaging systems that view the same scene repeatedly. Current research programs based on the processing of side-looking radar imagery show that spatial alignment of the various parts of the image must be highly accurate if noise in the difference picture is to be reduced to acceptably low levels. Typically, the spatial alignment accuracy must be better than one-fourth of the diameter of the smallest resolvable feature in the imagery, and this often requires several hundred degrees of freedom in the performance of the map warp for images that are of the order of 107picture cells (pixels) in size. Gray scale rectification of conjugate sampling points is less difficult, requiring typically only 10 to 20 percent as many degrees of freedom. Point by point adjustment for differences in mean transparency and contrast is employed. Recently developed equipment provides a continuous pipeline processing capability. With this equipment, each picture element of the second image is transformed with four degrees of freedom (two spatial and two gray scale). The digital correlator is capable of processing 4×105six-bit picture elements per second when used in conjunction with a CDC 1700 computer.

127 citations


ReportDOI
19 Oct 1972
TL;DR: In this paper, a set of equations is developed which permits one to calculate acquisition, classification and identification ranges for ship targets when viewed by an airborne forward looking infrared (FLIR) imaging device.
Abstract: : In this technical memorandum a set of equations is developed which permits one to calculate acquisition, classification and identification ranges for ship targets when viewed by an airborne forward looking infrared (FLIR) imaging device. Inputs to the model are the average dimensions and aspect angle of the target, the average ship-to-background temperature difference, the surface air temperature and relative humidity, and the nominal resolution, noise equivalent temperature difference and altitude of the FLIR. Novel features of the model are the use of square picture elements (pixels) to establish criteria for acquisition, classification and identification and the relating of pixel size to the minimum resolvable temperature difference of the FLIR.

7 citations


Journal ArticleDOI
TL;DR: It has been found that if the tristimulus values of a color are transmitted over the channel, the effects of channel errors are to desaturate ali colors toward a mid-gray and shift the hue of transmitted colors toward cyan, magenta, or yellow.
Abstract: This paper considers the effects of channel errors on the digital transmission of color images. In the transmission system analyzed, each picture element of a color image is represented by three color components. Two cases are considered: the tristimulus representation and the luminance and chromaticity representation. Each color component is coded with a constant-word-length PCM code and passed through a binary symmetric channel. Channel errors are related to chromaticity and luminance errors in a reconstructed image by the use of color space diagrams. Statistical characteristics of image errors are determined for various color representations. It has been found that if the tristimulus values of a color are transmitted over the channel, the effects of channel errors are to desaturate ali colors toward a mid-gray. For luminance/chromaticity representations, channel errors tend to shift the hue of transmitted colors toward cyan, magenta, or yellow.

2 citations


Proceedings ArticleDOI
01 Dec 1972
TL;DR: A technique of image compression through linear transformation which reduces the image information while generating a set of features for optimal image discrimination and feature generation that is optimal for image classification rather than for image representation is concerned.
Abstract: This paper is concerned with a technique of image compression through linear transformation which reduces the image information while generating a set of features for optimal image discrimination. This method consists of partitioning the original image into non-overlapping sub-images and applying the transgeneration technique to the subimages. The objective of this transgeneration technique is image data compression and feature generation that is optimal for image classification rather than for image representation. The technique is applied to transgenerate features fYom scintigraphic images for the detection of brain tumors. Some performance results for the classification of normal/abnormal classes of brain scans are presented. Some possible extensions and modifications of this work are briefly described.