Edge enhancement

About: Edge enhancement is a research topic. Over the lifetime, 2324 publications have been published within this topic receiving 30962 citations.

Optical correlator using electronic image preprocessing

Abstract: An optical processing system uses spatial filtering to recognize two-dimensional functions and images. Images of real objects are captured with a television camera. The electronic signals representing the two-dimensional function or image are electronically preprocessed, such as by edge enhancement techniques or by applying a curvature function, and displayed on a narrow-band-phosphor cathode ray tube or television monitor. The monitor image is used directly as the input to an incoherent holographic correlator. Alternatively, the monitor image is used to modulate a source of coherent radiation such as a laser via a spatial light modulator to generate a modulated optical signal which is the input to a coherent holographic correlator. Analyzer circuitry with an optical detector at the correlation plane analyzes the shape of the correlation function to determine the intensity and position of its peak. The input to the CRT or monitor may also be in the form of non-optically generated electronic signals representative of a two-dimensional function for display in graphic form by the CRT or monitor.

Quantitative evaluation of a single-distance phase-retrieval method applied on in-line phase-contrast images of a mouse lung.

Abstract: Propagation-based X-ray phase-contrast computed tomography (PBI) has already proven its potential in a great variety of soft-tissue-related applications including lung imaging. However, the strong edge enhancement, caused by the phase effects, often hampers image segmentation and therefore the quantitative analysis of data sets. Here, the benefits of applying single-distance phase retrieval prior to the three-dimensional reconstruction (PhR) are discussed and quantified compared with three-dimensional reconstructions of conventional PBI data sets in terms of contrast-to-noise ratio (CNR) and preservation of image features. The PhR data sets show more than a tenfold higher CNR and only minor blurring of the edges when compared with PBI in a predominately absorption-based set-up. Accordingly, phase retrieval increases the sensitivity and provides more functionality in computed tomography imaging.

Characterization of the phase-contrast radiography edge-enhancement effect in a cabinet x-ray system.

Abstract: The purpose of this study was to demonstrate that a commercially available cabinet x-ray system is capable of phase-contrast radiography (PC-R) and to evaluate the effect of different system parameters on the degree of edge enhancement. An acrylic plastic edge phantom was imaged at different tube potentials (25–60 kV) and in different geometries (variable object-to-detector distances, R2, at a constant source-to-detector distance, R1 + R2). In addition, the effect of noise on the perceived edge enhancement was studied as a function of exposure time. Our results show that a modest degree of phase contrast can be achieved in an unmodified cabinet x-ray system. In addition, the particular system evaluated allowed low-noise PC-R images to be obtained with short (6 s or less) exposures. These results suggest that with appropriate geometric choices PC-R is already available to a wide range of research scientists for use in both small-animal and human-specimen experiments.

Selective near-perfect absorbing mirror as a spatial frequency filter for optical image processing

Abstract: Spatial frequency filtering is a fundamental enabler of information processing methods in biological and technical imaging. Most filtering methods, however, require either bulky and expensive optical equipment or some degree of computational processing. Here, we experimentally demonstrate real-time, on-chip, all-optical spatial frequency filtering using a thin-film perfect absorber structure. We experimentally demonstrate edge enhancement of an amplitude image and conversion of phase gradients to intensity modulation in an image. The device is used to demonstrate enhancement of an image of pond algae.