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A real-time contour detector and data acquisition system for an angiographic apparatus having a video scanner for converting an X-ray image of a structure characterized by a change in brightness level compared with its surrounding into video format and displaying the X-ray image in recurring video f

A real-time contour detector and data acquisition system for an angiographic apparatus having a video scanner for converting an X-ray image of a structure characterized by a change in brightness level compared with its surrounding into video format and displaying the X-ray image in recurring video fields.The real-time contour detector and data acquisition system includes track and hold circuits adapted to be coupled to the video scanner for sampling the brightness level of predetermined sample points of the current video field in the region of the last detected border point; a reference level analog computer circuit connected to the track and hold circuits and responsive to the sampling of the brightness level of the predetermined sample points for generating a reference brightness level at which the next border point can be detected; and analog compartor connected to the reference level circuit for comparing the brightness level along a video scan line in the current video field with that of the reference brightness level to detect the next border point; a digital processor connected to the comparator and the track and hold circuits and responsive to the detection of a border point for enabling the comparator only within an area of the current video field covered by a narrow expectation window centered about the expected next border position and for determining the sample points to be sampled by the track and hold circuits; a field memory connected to and accessible by the processor for storing the coordinates of the detected border points in the preceding two video fields to partially define the center of the expectation window; and a computer interface connected to the comparators for storing the detected border points in the computer.

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