1. Field of the Invention
The present invention relates to a method and apparatus for discriminating eye fundus blood vessels, and more particularly to a method and apparatus for discriminating eye fundus blood vessels in which a light beam of prescribed wavelength is projected into the eye fundus and light scattered therefrom is detected to distinguish a blood vessel in the eye fundus.
2. Description of the Prior Art
In typical ophthalmological apparatuses such as optical coagulators or eye fundus blood velocimeters, a prescribed beam of monochromatic coherent light is projected to a region in the eye fundus and light scattered therefrom is detected to discriminate fundus blood vessels in order to recognize whether an eye being examined is moving or immobile There are also methods and apparatuses for obtaining color images of the eye fundus by scanning the eye fundus with light which includes the wavelength regions of the three primary colors, red (R), green (G) and blue (B), and discriminating fundus blood vessels by receiving the light thereby scattered by the eye fundus.
A drawback of systems based on the use of monochromatic light is that, during the examination procedure, any deviation in the alignment between the patient and the apparatus will change the quantity of scattered light that is detected, resulting in erroneous blood-vessel recognition. With apparatuses which project multi-chromatic light such as RGB light, for example, onto the eye fundus and detect and convert the scattered light from the eye fundus to obtain an image signal which is used to identify a blood vessel, attention must be paid to the fact that light absorbing and reflecting characteristics of the fundus blood vessels and surrounding tissues differ depending on the wavelength of the light concerned. This fact is not fully recognized in the prior art, so that the signal obtained from the scattered light has a poor signal-to-noise (S/N) ratio which gives rise to erroneous blood-vessel recognition.