Image pickup apparatus and image pickup method

An image pickup apparatus comprising:

• an imaging element including an imaging plane on which pixels configured convert light to an electric signal are arrayed;
• a body configured to hold the imaging element;
• a reception circuit configured to receive an optical characteristic of an image pickup optical system configured to form a subject image on the imaging plane;
• an imaging control circuit configured to acquire a plurality of first images corresponding to the subject image formed on the imaging plane by the image pickup optical system by causing the imaging element to execute exposure a plurality of times in accordance with an imaging instruction that is input;
• an attitude detection circuit configured to detect a tilt angle each time exposure is executed, the tilt angle being a change amount of an attitude of the body from a reference attitude in a direction with a rotational axis along a direction perpendicular to an optical axis of the image pickup optical system;
• and
• a system controller including a keystone correction circuit and a composite circuit, the keystone correction circuit being configured to correct a keystone distortion occurring in each of the plurality of first images due to a change of the attitude of the body, by keystone correction based on the tilt angle corresponding to the plurality of first images, and the optical characteristic, thereby generating a plurality of second images, and the composite circuit being configured to generate a third image by compositing the plurality of second images,
• wherein the imaging control circuit is configured to cause the imaging element to execute exposure a plurality of times with a predetermined exposure time from when imaging is started to when imaging is judged to be finished, thereby acquiring the plurality of first images,
• the keystone correction circuit is configured to generate the plurality of second images by keystone-correcting the plurality of first images each time an image of the plurality of first images is acquired, and
• the composite circuit is configured to generate the third image by compositing the plurality of second images acquired from a start of imaging, by addition compositing or comparative brightness compositing, each time an image of the plurality of second images is acquired, and
• the optical characteristic includes at least a focal distance of the image pickup optical system, and
• the image pickup apparatus further includes:
• an image blur detection sensor configured to detect an image movement amount during exposure of the subject image on the imaging plane, based on the focal distance and the tilt angle;
• and
• an image blur correction actuator configured to adjust a positional relationship between the subject image and the imaging plane, based on the image movement amount, and
• the system controller further includes, a correction limit determination circuit configured to judge whether the image movement amount reaches a preset threshold value or more, and to judge that imaging is to be finished, when the correction limit determination circuit judges that the image movement amount is the preset threshold value or more.

An image pickup apparatus comprising:

• an imaging element including an imaging plane on which pixels configured to convert light to an electric signal are arrayed;
• a body configured to hold the imaging element;
• a reception circuit configured to receive an optical characteristic of an image pickup optical system configured to form a subject image on the imaging plane;
• a body configured to hold the image element;
• a reception circuit configured to receive an optical characteristic of an image pickup optical system configured t form a subject image on the imaging plane;
• an imaging control circuit configured to acquire a plurality of first images corresponding to the subject image formed on the imaging plane by the image pickup optical system by causing the imaging element to execute exposure a plurality of times in accordance with an imaging instruction that is input;
• an attitude detection circuit configured to detect a tilt angle each time exposure is executed, the tilt angle being a change amount of an attitude of the body from a reference attitude in a direction with a rotational axis along a direction perpendicular to an optical axis of the image pickup optical system;
• and
• a system controller including a keystone correction circuit and a composite circuit, the keystone correction circuit being configured to correct a keystone distortion occurring in each of the plurality of first images due to a change of the attitude of the body, by keystone correction based on the tilt angle corresponding to the plurality of first images, and the optical characteristic, thereby generating a plurality of second images, and the composite circuit being configured to generate a third image by compositing the plurality of second images;
• wherein the optical characteristic includes a focal distance of the image pickup optical system and a projection method,
• the system controller further includes a keystone correction execution determination circuit configured to determine whether or not to execute the keystone correction, based on at least one of the focal distance and the projection method, and
• the composite circuit is configured to acquire the third image by compositing the plurality of first images, when the keystone correction execution determination circuit determines that the keystone correction is not executed.

An image pickup method which an image pickup apparatus executes, the image pickup apparatus including an imaging element including an imaging plane on which pixels configured to convert light to an electric signal are arrayed, a body configured to hold the imaging element, and an image pickup optical system configured to form a subject image on the imaging plane, the method comprising:

• acquiring an optical characteristic of the image pickup optical system;
• acquiring a plurality of first images corresponding to the subject image formed on the imaging plane by the image pickup optical system by causing the imaging element to execute exposure a plurality of times in accordance with an imaging instruction that is input;
• detecting a tilt angle each time exposure is executed, the tilt angle being a change amount of an attitude of the body from a reference attitude in a direction with a rotational axis along a direction perpendicular to an optical axis of the image pickup optical system;
• and
• correcting a keystone distortion occurring in each of the plurality of first images due to a change of the attitude of the body, by keystone correction based on the tilt angle corresponding to the plurality of first images, and the optical characteristic, thereby generating a plurality of second images;
• generating a third image by compositing the plurality of second images;
• updating the reference attitude, based on a maximum value and a minimum value of the tilt angle detected with respect to each of the plurality of first images;
• and
• re-detecting the tilt angle with respect to each of the plurality of first images, based on the updated attitude.