Image processing method for obtaining corneal vertexes

Abstract

The invention discloses an image processing method for obtaining corneal vertexes. The method comprises the following steps of continuously acquiring N frames of images at a high speed to synthesize aframe of image with minimum noise; acquiring a potential corneal reflection area through image binaryzation and blob analysis so that a to-be-processed area is reduced; carrying out gray stretchingon the potential light spot area; carrying out double-threshold binarization and blob analysis; obtaining a gray gravity center and a light spot boundary coordinate of a cornea vertex area; taking a gray vertex as a center; pulling the ray outwards every a certain angle to obtain a gray sequence on the ray; carrying out gaussian fitting based on a nonlinear least square method on gray scale data of the strip ray group to acquiresub-pixel coordinate values of corneal vertexes; finally, according to the jump of the gray value on the ray at the boundary; solving a sub-pixel-level coordinate boundary; corneal vertex and light spot boundary information obtained through the method can be combined with pupil center position and other related information obtained through other devices to obtain Kappa angle Alpha angle and other related information of eyes, and reliable basic data are provided for subsequent further eye refraction parameter obtaining.

Description

technical field [0001] The invention relates to the technical field of image processing, in particular to an image processing method for obtaining corneal vertices. Background technique [0002] The Kappa angle is the angle between the visual axis and the pupillary axis. Normal people generally have a positive Kappa angle of about 5°. Since the visual axis is a theoretical line, it cannot be directly measured clinically. Therefore, when various instruments measure the Kappa angle, they use the distance between the point of fixation on the cornea and the center of the pupil on the corneal plane to express it, that is, the angular distance between the line of sight and the pupil axis on the corneal plane. There are many measurement methods for Kappa angle. The earlier measurement methods mainly include corneal light reflection method, perimetry, synopic machine, etc., but the measurement accuracy of these methods is very low. The Kappa angle measurement methods currently used...

AI Technical Summary

Problems solved by technology

The measurement accuracy of this method is limited by the diameter of the ring. The larger the diameter of the ring, the lower the accuracy, and it cannot really project to the corneal apex. When the corneal apex and its surroundings are of irregular shape, the center of the ring and The deviation of the true corneal apex will be larger

The Scheimpflug imaging technology uses slit light to irradiate the eye vertically, and obtains the anterior segment section image from the side, so as to obtain the corneal height information to determine the corneal apex. resulting in a certain detection error

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