Topic
Edge enhancement
About: Edge enhancement is a research topic. Over the lifetime, 2324 publications have been published within this topic receiving 30962 citations.
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TL;DR: It is demonstrated that PC digital tomosynthesis retains the edge-enhancement observed in planar PC radiograph and further improves soft-tissue conspicuity by reducing the effects of superimposed tissue structure.
Abstract: Purpose: Phase-contrast (PC) edge enhancement occurs at the boundary between different tissues and is an interference effect that results from the differential phase-shifts that the x-rays acquire while traversing the two tissues. While observable in planar phase-contrast radiographs, the impact of digital tomosynthesis on this edge enhancement effect has not been previously reported. The purpose of this work is to demonstrate: (1) that phase-contrast digital tomosynthesis (PC-DTS) is possible with a conventional x-ray source, (2) that the reconstructedtomosynthesisimages demonstrate and retain edge enhancement as compared to planar phase-contrast radiographs and (3) tomosynthesis improves object contrast by reducing the effects of superimposed structures. Methods: An unmodified, commercially available cabinet x-ray system (Faxitron LX-60) was used. The system contains a tungsten anode x-ray tube that was operated at 24 kVp and 3 mAs for each PC radiographicimage taken, with a nominal focal spot size of 0.010 mm. The digital detector uses CsI/CMOS with a pixel size of 0.054 mm × 0.054 mm. Objects to be imaged were attached to a computer-controlled rotating motor and are rotated ± 25° about a central position in one degree increments. At each increment, three phase-contrast radiographs are taken and then averaged to reduce the effect of noise. These planar images are then used to reconstruct a series of 56 longitudinal tomographic images with an image offset increment of about 0.7 mm. Results: Tomographic z-plane resolution was measured to be approximately 4 mm. When compared to planar PC images, the tomosynthesisimages were shown to retain the PC boundary edge enhancement in addition to an improvement in object contrast. Conclusions: Our work demonstrates that PC digital tomosynthesis retains the edge-enhancement observed in planar PC radiograph and further improves soft-tissue conspicuity by reducing the effects of superimposed tissue structure.
22 citations
TL;DR: In this paper, a degenerate four wave mixing (DFWM) configuration in BSO (Bi 12 SiO 20 ) plus an additional image modification beam was used to selectively erase certain spatial frequencies of the object, producing a modified reconstructed image beam.
22 citations
TL;DR: An enhanced error diffusion halftoning algorithm for which the filter weights and the quantizer thresholds vary depending on input pixel value and a tone dependent threshold is designed to reduce edge effects and start-up delay is presented.
Abstract: We present an enhanced error diffusion halftoning algorithm for which the filter weights and the quantizer thresholds vary depending on input pixel value. The weights and thresholds are optimized based on a human visual system model. Based on an analysis of the edge behavior, a tone dependent threshold is designed to reduce edge effects and start-up delay. We also propose an error diffusion system with parallel scan that uses variable weight locations to reduce worms.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
22 citations
TL;DR: A technique for automatic detection of drainage channel networks on single digital images acquired by conventional remote sensing satellites such as Landsat and SPOT, using a multi-level knowledge-based approach.
Abstract: We present a technique for automatic detection of drainage channel networks on single digital images acquired by conventional remote sensing satellites such as Landsat and SPOT. Since these satellites are Sun-synchronous, the approximate local Sun angle at time or image acquisition is always known. Consequently, the spatial behaviour of shading with respect to channels and other topo-morphological features is known. This knowledge has been used to advantage in this work. We use a multi-level knowledge-based approach for this detection process. The first and lowest level deals with image processing: radiometric and edge enhancement, edge detection and consolidation, and skeletonization; resulting in a complex network of lines. The second (intermediate) level of knowledge for network extraction performs a categorization of line segments in order of resemblance to channel elements based on the strength and local disposition of shading. The highest level of knowledge that has been applied, reconstruc...
22 citations
TL;DR: In this paper, the spectral-moment method was proposed for detecting edges in potential-field anomalies based on the second spectral moment and its statistically invariable quantities, and the spectral moment was used for edge enhancement.
Abstract: Edge enhancement in potential-field data helps geologic interpretation, where the lineaments on the potential-field frequently indicate subsurface faults, contacts, and other tectonic features. Therefore, a variety of edge-enhancement methods have been proposed for locating edges, most of which are based on the horizontal or vertical derivatives of the field. However, these methods have several limitations, including thick detected boundaries, blurred response to low-amplitude anomalies, and sensitivity to noise. We have developed the spectral-moment method for detecting edges in potential-field anomalies based on the second spectral moment and its statistically invariable quantities. We evaluated the spectral-moment method using synthetic gravity data, EGM-2008 gravity data, and the total magnetic field reduced to the pole. Compared with other edge-enhancing filters, such as the total horizontal derivative (TDX), profile curvature, curvature of the total horizontal gradient amplitude, enhancement...
22 citations