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Digital camera

Digital camera description/claims

This invention relates to a digital camera.

As a method of autofocus (AF) of digital cameras, a contrast detection method is heretofore known. In the contrast detection method, image signals are obtained by imaging an object by an imaging element such as a CCD, a component of a predetermined spatial frequency band is extracted from the image signals contained within a predetermined AF area within an image and a focus evaluation value is calculated by integrating its absolute value. The focus evaluation value is a value that corresponds to the contrast in the focal point detection area, and the value increases as the contrast increases. Based on the characteristic that the contrast of an image becomes higher as a focus lens assumes a position closer to a focus position, the lens position at which the focus evaluation value peaks (hereafter referred to as the peak position) is determined, the peak position is determined to be the focus position, and the focus lens is driven to this focus position (Patent Reference 1).

[Patent Reference 1] Japanese Published Patent Application 2003-315665

However, for detecting the peak position of the contrast, which is the focus position, the focus evaluation values are calculated at predetermined intervals, moving the focus lens along an optical axis, the focus evaluation values of those points are analyzed, and the peak position is detected. Therefore, there has been a problem that bringing an object into focus takes time and that a moving object cannot be brought into focus.

An object of this invention is to provide a digital camera in which an object can be more accurately brought into focus, and shooting can be performed.

The digital camera according to claim 1 is provided with an imaging unit that receives and images light from an object which has passed through shooting optical system; a recognition unit that recognizes a feature region of the object by using an image imaged by the imaging unit; a detection unit that detects a size of the feature region recognized by the recognition unit; and a control unit that predicts a distance to the object after a predetermined time according to the size of the feature region and controls the shooting optical system so as to bring the object into focus.

In the digital camera according to claim 2, the digital camera according to claim 1 is further provided with a distance calculation unit that calculates a distance to the object according to the size of the feature region; and a speed calculation unit that calculates a moving speed of the object according to a time change of the distance to the object, in which the control unit predicts the distance to the object calculated by the distance calculation unit and the distance to the object according to the moving speed of the object calculated by the speed calculation unit.

In the digital camera according to claim 3, based on the digital camera according to claim 2, the distance calculation unit calculates the distance to the object based on position information of a lens constituting the shooting optical system, and calculates the distance to the object based on the calculated distance to the object and the size of the feature region after calculating the distance to the object based on the position information of the lens constituting the shooting optical system.

In the digital camera according to claim 4, based on the digital camera according to any of claims 1-3, the control unit predicts the distance to the object at the time of imaging based on the time between a shooting execution operation and imaging by the imaging unit, and controls the shooting optical system so as to bring the object into focus at the time of imaging by the imaging unit.

In the digital camera according to claim 5, the digital camera according to any of claims 1-4 is further provided with a registration unit that selects the feature region of the object for predicting the distance to the object, from the feature regions recognized by the recognition unit, and registers feature information of the selected feature region of the object, in which after feature information of the feature region of the object is registered, the recognition unit recognizes the feature region of the object based on the feature information of the feature region of the object.

In the digital camera according to claim 6, the digital camera according to claim 5 is further provided with a record control unit that stores in a recording medium an image, which has been obtained by imaging by the imaging unit, in which the registration unit registers the feature information of the feature region of the object based on the image stored in the recording medium.

In the digital camera according to claim 7, based on the digital camera according to claim 5 or 6, the feature information of the feature region is at least one of position information of a lens constituting the shooting optical system, the distance to the object, and the size of the feature region.

In the digital camera according to claim 8, based on the digital camera according to claim 4, a shooting condition is modified in response to one of calculation results of the distance calculation unit and the speed calculation unit.

In the digital camera according to claim 9, based on the digital camera according to claim 8, the shooting condition is one of a shutter speed and ISO sensitivity.

In the digital camera according to claim 10, based on the digital camera according to any of claims 1-9, the control unit predicts the distance to the object after the predetermined time based on the size of a plurality of the feature regions, existing on a plurality of images time-sequentially obtained by the imaging unit.

According to this invention, a digital camera is provided in which an object can be more accurately brought into focus, and shooting can be performed.

• Provisional Patent
• Utility Patent

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