| 摘要 |
A fast focusing method for a digital camera is applied in the digital camera to judge whether a focusing focal length of the digital camera needs to be adjusted in an auto focusing stage. The fast focusing method includes capturing a target image at a reference focal length; performing a blur detection procedure on the target image to acquire a focus value; setting a focusing focal length range covering the reference focal length when the focus value is between a lower limit focusing threshold and an upper limit focusing threshold; capturing corresponding comparison images at different focusing focal lengths respectively in the focusing focal length range; calculating a contrast value of each comparison image; and calculating the contrast values and a target focal length through a quadratic curve approximation method, and adjusting lenses of the digital camera to the set target focal length to perform shooting.
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