<p>We propose a new method and software for measuring blood vessel diameters
from fundus photographs. In this method the edge of the blood vessel is the two
minimum points in the luminance profile and diameter is distance between
minimum points. We noticed the relation between W-shape of luminance profile at
blood vessel transversal line and cylindrical shape, and analyzed the validity
of this method using the diffuse reflection model of a cylinder shape based on
the optics. The simulation image by the diffuse reflection model of the
cylinder was similar to that of the blood vessel images. A newly developed
software using the minimum points can measure repeated measurement in a series
of photographs at the same point of the same person. The data of the repeated
measurement of each person showed stability, and the coefficient of variation
showed no affection of different diameter and arteriovenous distinction. Hence,
we believe that the minimum points are valid as blood vessel edges. The
software that measures these blood vessel edges has an extremely simple
measurement procedure, possesses few errors, and is easy to automate. This
method is relevant because the central reflex, which has not been utilized
previously, optically represents the cylindrical three-dimensional structure of
blood vessels.</p><div><div>
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Segmentation of Retinal Blood Vessels Based on Cake Filter
