1. Field of the Invention
The present invention relates to an ophthalmic image sensing apparatus including an examination optical system for examining an eye to be examined and an image pickup optical system for picking up an image of the eye to be examined.
2. Related Background Art
In an eye fundus examination, a color image is acquired for diagnosis using an ophthalmic image sensing apparatus such as an eye fundus camera. When ocular circulation of blood vessels on retina and pigment epithelium of the retina are to be examined in detail because of, for example, diabetic retinopathy, visible fluorescent image sensing (hereinafter referred to as Fluo image sensing) is performed. When choroid is to be examined because of macular degeneration, near-infrared fluorescent image sensing (hereinafter referred to as ICG image sensing) is performed.
Of those image sensings, the ICG image sensing has an advantage in that a fluorescent agent is more quickly circulated, a dynamic range of a change in fluorescent intensity and a variation in time are very large.
Therefore, in order to obtain a preferable image based on a wide dynamic range of the fluorescent intensity, it is necessary that an examiner change a gain of an image pickup element according to an output signal therefrom or frequently adjust a strobe scope light intensity.
The following method has been disclosed (see Japanese Patent Application Laid-Open No. H04-189341). When an image sensing mode such as a color image sensing mode is shifted to an ICG image sensing mode, because the fluorescent intensity of the ICG is high in the early stage thereof, image sensing is performed while strobe scope emission is inhibited without any condition. In the later stage, when the examiner determines that the strobe scope emission is necessary, strobe scope image sensing is performed by the operation of a light emission inhibition releasing means.
There has been disclosed a method of detecting output values from respective pixels of an image pickup element on a scanning line and calculating a strobe scope emission intensity based on the result to control an emission intensity of an image sensing light source (see JP-B 3056287).
In the above-mentioned conventional example, when a preferable image sensing condition is to be set, the examiner requires skill to simultaneously adjust and set a strobe scope light intensity and a gain.
In the case of the control for inhibiting the strobe scope emission when the image sensing mode is shifted to the ICG image sensing mode, there is an advantage to the non-emission of strobe scope light in the early stage. However, in the later stage of the image sensing, the strobe scope light image sensing is required in the relation with the sensitivity of the image pickup element.
At this time, it is necessary to allow the strobe scope emission using the strobe scope emission releasing means by the examiner.
An image sensing condition is controlled depending only on whether the strobe scope light is emitted or not and the emission intensity.
In the method of detecting the output values from the respective pixels of the image pickup element to control the strobe scope emission intensity, the strobe scope light intensity is changed depending on a level of an observation light intensity during the examination performed by the examiner. In addition, the strobe scope light intensity is changed depending on the selection of a target scanning line on the image pickup element in some cases, so the learning of the image sensing technique is required.