Showing papers on "Edge enhancement published in 1988"
TL;DR: A single-beam interferometer that effectively subtracts an exponentially weighted history of the input from the current value, thus functioning as a novelty filter is experimentally demonstrated.
Abstract: We have experimentally demonstrated a single-beam interferometer that effectively subtracts an exponentially weighted history of the input from the current value, thus functioning as a novelty filter. The single-beam interferometer uses signal depletion due to noise amplification (fanout) in a specially cut crystal of photorefractive BaTiO(3). To demonstrate its real-time operation we used a Hughes liquid-crystal light valve to convert a video image into a phase- and/or amplitude-modulated input signal. Potential applications of this interferometer include image-clutter removal, motion detection and tracking, edge enhancement, and image time differentiation.
64 citations
TL;DR: The Sobel operator was found to be superior to the Roberts operator in edge enhancement and a theoretical explanation for the superior performance was developed based on the concept of analyzing the x and y Sobel masks as linear filters.
Abstract: Reference is made to the Sobel and Roberts gradient operators used to enhance image edges. Overall, the Sobel operator was found to be superior to the Roberts operator in edge enhancement. A theoretical explanation for the superior performance of the Sobel operator was developed based on the concept of analyzing the x and y Sobel masks as linear filters. By applying pill-box, Gaussian, or median filtering prior to applying a gradient operator, noise was reduced. The pill-box and Gaussian filters were more computationally efficient than the median filter with approximately equal effectiveness in noise reduction. >
51 citations
01 Jan 1988
TL;DR: A computerized system is described for 3-D reconstruction, manipulation, geometrical analysis, and postprocessing of biomedical models that includes the availability of modular built-in functions and the flexibility of adding dedicated or general-purpose functions.
Abstract: A computerized system is described for 3-D reconstruction, manipulation, geometrical analysis, and postprocessing of biomedical models. This system, based on an IRIS 3020 graphics workstation from Silicon Graphics, can perform (1) preprocessing of 3-D biomedical data coming from serial slices, (2) 3-D generation and coding of the underlying structures, and (3) display, interactive object manipulation, and geometrical analysis. The main features of the modeler are the availability of modular built-in functions and the flexibility of adding dedicated or general-purpose functions. Such functions can range from specific image preprocessing algorithms (soft tissue segmentation, edge and contrast enhancement, contour detection) to postprocessing functions that allow visualization of modeling analysis results. >
38 citations
Journal Article•
TL;DR: In this paper, the three best methods for enhancing geological structure were found to be: (1) a simple linear contrast stretch; (2) a mean or median low-pass filter to reduce speckle prior to edge enhancement; (3) a K nearest-neighbor average to cosmetically reduce specks; and (4) a modification of the Moore-Waltz (1983) technique.
Abstract: Various digital enhancement techniques for SAR are compared using SIR-B and Seasat images of the Canadian Shield. The three best methods for enhancing geological structure were found to be: (1) a simple linear contrast stretch; (2) a mean or median low-pass filter to reduce speckle prior to edge enhancement or a K nearest-neighbor average to cosmetically reduce speckle; and (3) a modification of the Moore-Waltz (1983) technique. Three look directions were coregistered and several means of data display were investigated as means of compensating for radar azimuth biasing.
23 citations
Patent•
23 May 1988TL;DR: A signal processing for a color thermal printing apparatus first corrects contrast and color and then provides edge enhancement as mentioned in this paper, which can be used to improve the quality of the printed image.
Abstract: A signal processing for a color thermal printing apparatus first corrects contrast and color and then provides edge enhancement.
12 citations
TL;DR: A method of spatial filtering in the frequency domain which enhances edges and boundaries, thus making small urban features, such as parks, tree-lined streets and new housing developments, visible on digital images with, for example, 30 m resolution is described.
Abstract: We describe a method of spatial filtering in the frequency domain which enhances edges and boundaries, thus making small urban features such as parks, tree-lined streets and new housing developments, visible on digital images with, for example, 30 m resolution. Hitherto, while satellite imagery has been useful because of its large area and repetitive coverage, the spatial resolution for multiband imagery has been such that it precluded the detailed studies which may now be possible. While spatial frequency filtering, edge enhancement, high-boost and directional filtering have been possible, this has generally involved the use of a convolution matrix whose elements have been defined from general empirical rules. Frequency domain operations offer the advantage of selectively tailoring the filter in order to enhance certain features.
8 citations
01 Feb 1988
TL;DR: In this paper, the edge enhancement is performed in BaTiO₃ by the same DFWM geometry, but the intensities of the object beam and writing beam are inverted.
Abstract: A hologram mechanism being produced in the photorefractive material is investigated. The edge enhancement is performed in BaTiO₃ by the same DFWM geometry. But the intensities of the object beam and writing beam are inverted. Good quality of edge enhancement is observed in real time with low incident light intensity.
6 citations
07 Jun 1988
TL;DR: In this paper, a multidimensional variance function filter is defined and its performance in edge enhancement applications is evaluated and the variance filter is shown to perform comparably to the Sobel filter and better than the compass gradient filter.
Abstract: A multidimensional variance function filter is defined and its performance in edge enhancement applications is evaluated. For the case of a 3*3 window, the variance filter is shown to perform comparably to the Sobel filter and better than the compass gradient filter. The advantage of the variance filter is its easy extendability to large window sizes and high dimensionality. The 3D variance filter is applied to the ventricular edge detection problem in gated nuclear cardiac imaging. >
5 citations
25 Sep 1988
TL;DR: In this article, the authors describe initial experience in echocardiographic image processing utilizing PIPE, a high-speed eight-stage array processor capable of performing multiple sequential algorithms at the real-time video field rate.
Abstract: The authors describe initial experience in echocardiographic image processing utilizing PIPE, a high-speed eight-stage array processor capable of performing multiple sequential algorithms at the real-time video field rate. The algorithms implemented include noise reduction with recursive temporal filtering, Gaussian spatial filtering, and edge-preserving smoothing; edge enhancement with the Sobel for magnitude and angle operators and difference-of-Gaussian convolutions; and velocity quantification with convected activation (a method for deriving normal motion from a sequence of binary edge maps described by A.M. Waxman et al., Proc. IEEE Conf. Comput. Vision Pattern Recognition, June 1988). It is shown that PIPE is a promising low-level engine for echocardiographic image processing. It remains, however, to be fully integrated with a high-level computer. >
3 citations
01 Jan 1988
TL;DR: In this article, the application of photoanisotropic As₂S₃ thin film to perform the nonlinear optical image processing such as subtraction, addition, contrast reversal and edge enhancement of the images is described.
Abstract: We have described the application of photoanisotropic As₂S₃ thin film to perform the nonlinear optical image processing such as subtraction, addition, contrast reversal and edge enhancement of the images. The experimental results are well explained by the extension of the theory for nonlinear optical polarization.
2 citations
22 Aug 1988
TL;DR: In this article, a real-time optical edge enhancement technique based on the polarizarion modulation of liquid crystal televisions is proposed, and experimental results and discussions are presented, where the authors propose a realtime edge enhancement method based on polarizer modulation.
Abstract: We propose a real-time optical edge enhancement technique based on the polarizarion modulation of liquid crystal televisions. Experimental results and discussions are presented.
25 Oct 1988
TL;DR: An algorithm for locating and tracing perceptually important edges, and for enhancement through nonstationary filtering, which yields encouraging experimental results when applied to images coded by the block list transform and vector quantization.
Abstract: Low bit rate image coding results in artifacts at reconstruction whose characteristics depend on the form of the coding/decoding algorithm used. A very common, and visually objectionable effect of most coding methods is distortion of edges. Classical spatially-invariant filtering techniques are of little use in removing this signal-dependent reconstruction error. This paper presents an algorithm for locating and tracing perceptually important edges, and for enhancement through nonstationary filtering. Edge detection and enhancement are reduced to a sequence of simple one-dimensional processes. The algorithm yields encouraging experimental results when applied to images coded by the block list transform and vector quantization.© (1988) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: It is shown that the operations of spatial filtering, such as smoothing, edge extraction, and edge enhancement, can be performed in the honeycomb waveguide network proposed.
Abstract: A honeycomb waveguide network for parallel signal processing, consisting of single-mode symmetrical Y junctions, is proposed. In this waveguide network, input guided-wave amplitudes are divided and then combined with the amplitudes of the adjacent waveguides. It is shown that the operations of spatial filtering, such as smoothing, edge extraction, and edge enhancement, can be performed. An example of the honeycomb waveguide network is discussed.
TL;DR: Using this model and local statistical measurements, a two-dimensional iterative image restoration algorithm is developed and results show that the visual qualities of the processed image are improved considerably over those obtained by conventional processing, particularly with respect to sharpness of restored images.