Patent ID: 8237785

Claim:
An automatic focusing apparatus for a microscope in which an image of fluorescence emitted from a cell is captured so as to acquire a cell image, the automatic focusing apparatus including a hardware control unit, and the hardware control unit comprising: an average-luminance calculating unit for calculating an average luminance of an entirety of the cell image based on a luminance distribution of the acquired cell image; a setting unit that sets: (i) as a lower limit luminance of a region where viable cells exist, one of the average luminance calculated by the average-luminance calculating unit and a first minimum point from the average luminance toward a high luminance side in the luminance distribution of the acquired cell image, and (ii) as an upper-limit luminance of the region where the viable cells exist, a second minimum point on the high luminance side of the lower-limit luminance in the luminance distribution of the acquired cell image; and a focus detection unit for detecting a position where a contrast value of the image is maximized as a focal position based on a luminance of an image of nuclei of the cells in the acquired cell image within a range between the lower-limit luminance and the upper-limit luminance set by the setting unit.