| 摘要 |
An image measuring method according to the present invention comprises an illuminance computing step of computing illuminance of a workpiece (W) based on an indicated value set and inputted from the outside as well as on luminance of an illumination unit (20), and an exposure time computing step of computing an exposure time of an image pick-up unit (30). The illumination unit (20) and the image pick-up unit (30) are controlled according to the computed illuminance and exposure time to pick-up an image, so that an image satisfying both the illuminance of the workpiece (W) and an exposure time of the image pick-up unit (30) can be picked up. Therefore, even in a case in which a controllable range of luminance of the illumination device (20) is limited and the luminance can not be raised beyond the upper limit, an image having the brightness higher than the upper limit of luminance of the illumination unit (20) can be picked up by prolonging the exposure time of the image pick-up unit (30).
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