Biomedical subjects

A C Bovik

Publications and source records attributed to A C Bovik.

4 recordsLinked to original sources

PubMed1991

Simultaneous multiple site arteriolar vasomotion measurement using digital image analysis.

An automatic digital image processing technique for simultaneous vasomotion analysis in peripheral microcirculation at multiple sites and in real time is presented. The algorithm utilizes either fluorescent or bright field micro-images of the vasculature as input. The video images are digitized and analyzed on-line by an IBM RT PC, using digital filtering and edge detection. The sampling frequency is higher than 5 Hz when only one site is tracked and decreases as the number of sites is incremented. Performance of the algorithm was tested for a hamster cutaneous microcirculation model.

Algorithms↗

PubMed1990

Color as a source of information in the stereo correspondence process.

Although previous research has shown that depth perception is weak for isoluminant stereograms, the possibility remains that color plays an important role in stereopsis when luminance variations are present. To examine this possibility, we measured the relative contribution of chromatic and luminance cues in solving the correspondence problem for ambiguous "wallpaper" stereograms composed of vertical bars. Using an ideal-observer analysis, we found that chromatic cues were used much more efficiently than luminance cues in disambiguating these stereograms when the patterns were presented on a dark background but were used with about equal efficiency when presented on a light background. Another experiment (using the same wallpaper patterns) showed that chromatic and luminance cues were also used with about equal efficiency in a standard stereo detection task. Some of the implications of these results for theories of stereo vision are discussed.

Color Perception↗

PubMed1990

3-D model of vascular network in rat skin obtained by stereo vision techniques.

The quantitative analysis of the depth of injury, penetration of therapeutic agents in tissues, and the regeneration of vascular patency after a graded degree of thermal injury requires a knowledge of the shape and spatial configuration of the vascular networks in the tissue. We have applied computational stereo vision techniques to describe the 3-D configuration of microvessels in full thickness rat skin vascular casts produced by perfusion of Yellow Microfil latex solution through the aorta. The principal concern is to describe the 3-D structure of vascular networks using a set of 3-D space curves. This representation is computed by integrating monocular and binocular processing; the 2-D curve representation of blood vessels computed through monocular analysis is integrated with disparity data to yield a space curve representation for each vessel. A connection diagram is also computed to indicate the connections existing among the computed space curve representations.

Algorithms↗

PubMed1987

A microcomputer-based vision system for area measurement.

A vision system for measuring the area of an arbitrarily shaped object is described. The algorithm consists of a gray-level thresholding technique combined with a region correction procedure based on mathematical morphology. All processing steps are carried out on a microcomputer system equipped with a video digitizer. The algorithm has been successfully applied to a number of images of medical interest including skin wounds and various microscopic-scale objects such as cell cross-sections and multicellular tissues. Excellent agreement between results obtained by the automatic method and by using standard mechanical means has been established experimentally. The approach is demonstrated by a number of experimental examples.

Algorithms↗