Conventionally, a technique of finding features of a subject specified by a camera user (hereinafter “user”) or a subject specified by an imaging apparatus based on predetermined conditions, these subject being hereinafter referred to as “main subject,” and estimating the area in image data where the main subject is present based on the features, is known. Particularly, the process of finding in a serial manner the area where the main subject is present in moving image data comprising image data that is inputted on a continuous basis, is carried out to follow the moving main subject, and therefore is often referred to as “tracking process” or “chasing process.” Note that the process of following a main subject in moving image data will be referred to as “tracking” with the present invention.
Various types of imaging apparatuses that find the position of a main subject by such a tracking process and that perform shooting control for shooting the main subject adequately, including focus control for focusing on the main subject and framing control for adjusting the shooting range, are proposed (for example, see Patent Literature 1 and Patent Literature 2). Usually, in framing control, panning, tilting and zooming are performed such that the main subject is placed in the center of the screen.
FIG. 1A to FIG. 1D are schematic diagrams of the operation showing an overview of the operation in case where the imaging apparatus with an automatic tracking function disclosed in Patent Literature 1 decides that the sight of the main subject is lost.
In FIG. 1A, in field of view 10, main subject 20 is present, and specified extraction position 30 showing the reference position to extract main subject 20 is set. In FIG. 1B, when main subject 20 hides behind another object 40, main subject 20 is no longer detected. When main subject 20 is no longer detected, the imaging apparatus continues the operation of detecting main subject 20 by fixing specified extraction position 30. If main subject 20 reappears in specified extraction position 30, main subject 20 is successfully detected and therefore the imaging apparatus releases fixed specified extraction position 30.
However, as shown in FIG. 1C, when main subject 20 reappears in field of view 10, if main subject 20 has moved, main subject 20 is not successfully detected due to the deviation from specified extraction position 30.
Therefore, as shown in FIG. 1D, if the sight of main subject 20 is lost, specified extraction position 30 is changed in a serial manner around the position immediately before the sight of main subject 20 was lost, so that, when main subject 20 reappears in field of view 10, main subject 20 can be detected even if main subject 20 has moved to another position from the position the sight of main subject 20 was lost.
Various ranges of searching specified extraction position 30 when the sight of main subject 20 is lost are proposed, including, for example, the entire screen and the default position which is typically the center of the screen.
Further, Patent Literature 2 discloses a camera that has an operating means for bringing a tracking field view indicating the position of the main subject, back to the default position. When the sight of the main subject is lost, the operating means is operated to bring the tracking field view back to the default position. Here, the default position refers to, for example, the center of the screen. As the operation after bringing the tracking field view back to the default position, Patent Literature 2 presents a scheme of clearing features of the main subject to wait for another tracking start command from the user and a scheme of acquiring features of the main subject in the default position to start a tracking process without waiting for another tracking start command from the user.