| 摘要 |
An auto-focus control circuit, an auto-focus control method and an image pickup apparatus are provided to reduce the risk of misfocusing when performing an auto-focus operation on an auto-focus target portion determined in a face image obtained by face detection. A focusing unit(13) includes a face detecting unit(130), an AF target region determination unit(131), an AF evaluation value calculation unit(132), a controller(133) and the lens driving unit(134). The face detecting unit detects a face region from the captured image generated by an image pickup unit(11) by using a face detection algorithm. Based on the size of the face region detected by the face detecting unit, the AF target region determination unit determines a region within the face region as an AF target region. The size of the face region is evaluated based on its area size, for example. If the face region is rectangular, the size thereof may alternatively be evaluated based on its horizontal and vertical lengths. The AF evaluation value calculation unit calculates, as an AF evaluation value, a contrast evaluation value at least on the region, corresponding to the AF target region, of the captured image data. As the contrast evaluation value, any of various parameters can be used as long as the parameter represents the contrast level of the captured image. The controller determines focusing conditions on the imaging surface of the image pickup device by using the AF evaluation values calculated by the AF evaluation value calculation unit, and thereby determines a position of the focusing lens to provide an in-focus condition. Specifically, the controller causes the image pickup unit to sequentially capture images while moving a focusing lens, and thus determines the position of the focusing lens where the AF evaluation value is the highest. The lens driving unit moves the focusing lens in the optical axial direction, under the control of the controller.
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