| 摘要 |
<p>PROBLEM TO BE SOLVED: To detect an edge gradient accurately with an optical system equivalent to a conventional one, to improve the accuracy of defocus control.SOLUTION: A transmissive target (3) having a linear and optically sharp edge is arranged in contact with a front face of a display unit so that an edge direction in an image captured by a camera (10) has a predetermined inclination with respect to a horizontal direction or a vertical direction of the captured image. An image processing unit (20) extracts pixel value data, for two lines, which corresponds to one line with one pixel width in the vertical direction intersecting with the edge direction or the horizontal direction, from the captured image having passed through the transmissive target and displayed as the constant luminance on the display unit, and calculates a pitch and gradient for one pixel on the basis of the extracted pixel value data for two lines, to quantitatively evaluate a defocus amount.</p> |
