Abstract: Flash emission is required when image data have a low luminance value and when it is determined that flash emission is not prohibited, the built-in flash is used for autofocus (AF). An AF evaluation value is obtained under the flash emission, and the lens is driven based on this value. This operation is repeated until it is determined that the lens is focused, and accurate AF is executed even in dark conditions.

Abstract: An AF control portion of a digital camera has therein a histogram generating circuit for generating a histogram of widths of edges in an AF area, a noise eliminating portion for eliminating noise components from the histogram, a histogram evaluating portion for calculating an evaluation value indicative of the degree of achieving focus from the histogram, and a contrast calculating circuit for calculating contrast in the AF area. Further, a driving amount determining portion for determining an amount of driving a focusing lens, and a driving direction determining portion for determining a direction of driving the focusing lens are provided. The driving direction determining portion determines the direction of driving the focusing lens by using contrast. The driving amount determining portion positions the focusing lens to an in-focus position promptly with high precision while changing the driving amount by using the evaluation value of the histogram and the contrast.

Abstract: Flash emission is required when image data have a low luminance value and when it is determined that flash emission is not prohibited, the built-in flash is used for autofocus (AF). An AF evaluation value is obtained under the flash emission, and the lens is driven based on this value. This operation is repeated until it is determined that the lens is focused, and accurate AF is executed even in dark conditions.

Abstract: A taking lens is driven in steps each producing movement of the taking lens through a distance greater than a depth of field, and an evaluation value is determined based on a captured image obtained from a CCD imaging device in each position to which the lens is driven. Then, a predetermined interpolation process is performed on a plurality of evaluation values obtained in respective positions to which the lens is driven to derive an in-focus position of the taking lens for bringing an in-focus plane into coincidence with an imaging plane. The taking lens is driven to the in-focus position to achieve an in-focus condition. This allows efficient determination of the in-focus position in a digital camera.