Showing papers on "Subpixel rendering published in 1985"
TL;DR: This work presents a method of retrieving suitable parameters for such discriminations on the local scale, based on the information contained in a bispectral (visible and 11 μm infrared) histogram, for the extraction of cloudiness on the subpixel scale.
Abstract: Two major problems in deriving cloud amounts and physical properties from satellite imagery are the selection of suitable surface-type discriminators, which may vary as a function of time and place, and the extraction of cloudiness on the subpixel scale. We present a method of retrieving suitable parameters for such discriminations on the local scale, based on the information contained in a bispectral (visible and 11 μm infrared) histogram. The application of these parameters to the retrieval of cloud information on both the pixel and subpixel scales is demonstrated.
24 citations
TL;DR: In this paper, an edge-and shape-guided correlation of control point areas for the analysis of multitemporal and multisource data is presented, supplemented by comparison of elementary objects, e.g., drawn lines, borders, and edges, whose positions are known with subpixel accuracy.
Abstract: The standard method for geometric registration of images consists of selecting control points in the two images and computing the correlation maximum of small subimages containing the control points. This method does not work well when applied to images taken at different seasons or with different sensors. The use of edge-based registration has been proposed to overcome these difficulties but has so far achieved no better than picture raster element accuracy. This paper presents edge-and shape-guided correlation (or comparison) of control point areas for the analysis of multitemporal and multisource data. The direct correlation of control areas for registration is supplemented by comparison of descriptions of elementary objects, e. g., drawn lines, borders, and edges, whose positions are known with subpixel accuracy. These methods have been implemented as a set of image registration modules within the context of the DIBIAS image processing system.
16 citations
TL;DR: A new light pen system using a real-time algorithm for computing the centroid of the intensity pattern seen by a photosensor that achieves an accuracy of better than one-quarter of a pixel on a cathode-ray-tube screen with 1K × 1K resolution is described.
Abstract: A new light pen system using a real-time algorithm for computing the centroid of the intensity pattern seen by a photosensor is described. This new light pen achieves an accuracy of better than one-quarter of a pixel on a cathode-ray-tube screen with 1K × 1K resolution. This corresponds to a capability of resolving 0.004 inch on a 15-inch screen, which is an improvement by a factor of at least 50 over the conventional light pens available today. The transistor-transistor logic hardware implementation of the algorithm is described in detail. The central part of the hardware is a real-time, moment-generating circuit that implements an efficient moment calculation algorithm reported earlier. Issues such as complexity of the hardware compared with the conventional techniques, and the possibility of implementing the algorithm in a single complementary metal-oxide semiconductor chip are addressed. Some line and curve drawing results sketched by the new light pen are presented and compared to similar drawings obtained by a conventional light pen.
6 citations
TL;DR: A new technique has been developed for geometrically rectifying images to subpixel accuracy in real time through high fidelity resampling that permits significant simplification and cost reduction for a remote sensing system by relaxing the optical/mechanical alignment tolerances.
Abstract: A new technique has been developed for geometrically rectifying images to subpixel accuracy in real time through high fidelity resampling. This technique permits significant simplification and cost reduction for a remote sensing system by relaxing the optical/mechanical alignment tolerances by about two orders of magnitude. A pipelined resampling processor has been built whose small size, weight, and power consumption permit it to be used on board a spacecraft or other vehicle. The high throughput of the processor prevents data logjams and permits the use of resampling kernels with better MTF and phase linearity than previously practical. A new design criterion that produces improved uniformity of MTF in the final image has been identified for the resampling kernels. These improvements over conventional resampling techniques result in improved data quality delivered to the end user and offer opportunities for streamlined data distribution. This technique and processor can also be applied to image motion compensation, data set merging, man-in-the-loop image warping, and image motion generation.
4 citations
10 May 1985
TL;DR: This project combined pattern recognition, image understanding and artificial intelligence techniques for space-based image processing with the attempt to use both optical and digital processing methods.
Abstract: : This project combined pattern recognition, image understanding and artificial intelligence techniques for space-based image processing. A special feature of this effort is the attempt to use both optical and digital processing methods. Subpixel target detection and tracking algorithms are analyzed and conclusions are presented regarding their suitability for this application. We also present an adaptive subpixel delay estimation method using Group-Delay Functions. Image understanding techniques for three dimensional scene interpretation are also discussed.
1 citations
01 Jan 1985
TL;DR: In this article, the authors present edge and shape-guided correlation of control point areas for the analysis of multitemporal and multisource data, e.g., drawn lines, borders, and edges whose positions are known with subpixel accuracy.
Abstract: The standard methodforgeometric registration ofimages consists ofselecting control points inthetwoimages andcomputing thecorrelation maximumofsmallsubimages containing thecontrol points. Thismethoddoesnotworkwellwhenapplied toimages taken atdifferent seasons orwithdifferent sensors. Theuseofedge-based registration hasbeenproposed toovercome thesedifficulties buthas sofarachieved nobetter thanpicture raster element accuracy. This paperpresents edge- andshape-guided correlation (orcomparison) of control point areas fortheanalysis ofmultitemporal andmultisource data.Thedirect correlation ofcontrol areas forregistration issupple- mented bycomparison ofdescriptions ofelementary objects, e.g., drawn lines, borders, andedges, whosepositions areknownwithsubpixel accuracy. Thesemethods havebeenimplemented asasetofimage registration modules within thecontext oftheDIBIASimageprocess- ingsystem. Keywords-Image registration, edgemodels, shapemodels, Hough transform, remotesensing, multitemporal images, subpixel accuracy.