Image taking device, portable terminal device, image taking method, and program

An image taking device which adjusts a taken image according to a positional relationship with a subject, said image taking device comprising:

• an image taking unit operable to take an image of the subject by using a multifocal lens;
• a distance computation unit operable to (i) compute a difference between a size of an object at a predetermined time and a size of the object at a present time, by determining an optical flow indicating a movement of an observed point that belongs to the object, the object being contained in the image taken by said image taking unit, and (ii) compute an amount of change of a distance from said image taking device to the subject based on the computed difference between the sizes of the object;
• a cut-out area computation unit operable to compute an image area to be cut out of the taken image based on the amount of the change of the distance to the subject;
• and
• an image cut-out unit operable to cut out a portion of the taken image according to a result of the computation by said cut-out area computation unit,
• wherein said distance computation unit is operable to (i) judge which state among states including divergent, steady and convergent represents each of the optical flow of a plurality of optical flows, by judging, for the optical flows, increasing or decreasing of a distance from each centroid of a plurality of the observed points to the observed point, the optical flows indicating movements of the plurality of the observed points that belong to the object;
• (ii) extract, from the judged optical flows, only optical flows that are in a state represented by most optical flows, (iii) determine, for the extracted optical flows, a difference between a distance from the centroid to the observed point at the predetermined time and at the present time, and (iv) compute an average value of the determined differences as the amount of the change.

An image taking method of adjusting a taken image according to a positional relationship between an image taking device and a subject, said method comprising:

• an image taking step of taking an image of the subject by using a multifocal lens;
• a distance computation step of (i) computing a difference between a size of an object at a predetermined time and a size of the object at a present time, by determining an optical flow indicating a movement of an observed point that belongs to the object, the object being contained in the image taken in said image taking step, and (ii) computing an amount of change of a distance from the image taking device to the subject based on the computed difference between the sizes of the object;
• a focal length computing step of computing the focal length of the multifocal lens based on the amount of the change of the distance to the subject;
• and
• a focal length control step of controlling the focal length of the multifocal lens so that the focal length of the multifocal lens is adjusted to the focal length computed by said focal length computation step,
• wherein said distance computation step includes (i) judging which state among states including divergent, steady and convergent represents each optical flow of a plurality of optical flows, by judging, for the optical flows, increasing or decreasing of a distance from each centroid of a plurality of the observed points to the observed point, the optical flows indicating movements of the plurality of the observed points that belong to the object;
• (ii) extracting, from the judged optical flows, only optical flows that are in a state represented by most optical flows, (iii) determining, for the extracted optical flows, a difference between a distance from the centroid to the observed point at the predetermined time and at the present time, and (iv) computing an average value of the determined differences as the amount of the change.

An image taking device which adjusts a taken image according to a positional relationship with a subject, said image taking device comprising:

• an image taking unit operable to take an image of the subject by using a multifocal lens;
• a distance computation unit operable to extract a reference figure contained in the image taken by said image taking unit, and compute a distance from said image taking device to the subject based on a difference between the reference figure at a predetermined time and the reference figure at a present time;
• a focal length computation unit operable to compute a focal length of the multifocal lens based on the distance to the subject;
• and
• a focal length control unit operable to control a focal length of the multifocal lens so that the focal length of the multifocal lens is adjusted to the focal length computed by said focal length computation unit,
• wherein said focal length computation unit is operable to weight a difference between the distance to the subject at the predetermined time and the distance to the subject at the present time to make variable a rate of contribution of (i) the difference between the distances to the subject, and (ii) an amount of change in the focal length of the multifocal lens.

An image taking method of adjusting by an image taking device a taken image according to a positional relationship with a subject, said image taking method comprising:

• taking an image of the subject by using a multifocal lens;
• extracting a reference figure contained in the image taken, and computing a distance from the image taking device to the subject based on a difference between the reference figure at a predetermined time and the reference figure at a present time;
• computing a focal length of the multifocal lens based on the distance to the subject;
• and
• controlling a focal length of the multifocal lens so that the focal length of the multifocal lens is adjusted to the focal length computed,
• wherein said computing of the focal length includes weighting a difference between the distance to the subject at the predetermined time and the distance to the subject at the present time to make variable a rate of contribution of (i) the difference between the distances to the subject, and (ii) an amount of change in the focal length of the multifocal lens.

A program product that is embodied on a computer-readable recording medium and used for an image taking device which adjusts a taken image according to a positional relationship with a subject, said program product causing a computer to execute:

• taking an image of the subject by using a multifocal lens;
• extracting a reference figure contained in the image taken, and computing distance from the image taking device to the subject based on a difference between the reference figure at a predetermined time and the reference figure at a present time;
• computing a focal length of the multifocal lens based on the distance to the subject;
• and
• controlling a focal length of the multifocal lens so that the focal length of the multifocal lens is adjusted to the focal length computed,
• wherein said computing of the focal length includes weighting a difference between the distance to the subject at the predetermined time and the distance to the subject at the present time to make variable a rate of contribution of (i) the difference between the distances to the subject, and (ii) an amount of change in the focal length of the multifocal lens.

An image taking device which adjusts a taken image according to a positional relationship with a subject, said image taking device comprising:

• an image taking unit operable to take an image of the subject by using a multifocal lens;
• a distance computation unit operable to extract a reference figure contained in the image taken by said image taking unit, and compute a distance from said image taking device to the subject based on a difference between the reference figure at a predetermined time and the reference figure at a present time;
• a cut-out area computation unit operable to compute an image area to be cut out of the taken image based on the distance to the subject;
• and
• an image cut-out unit operable to cut out a portion of the taken image according to a result of the computation by said cut-out area computation unit,
• wherein said cut-out area computation unit is operable to weight a difference between the distance to the subject at the predetermined time and the distance to the subject at the present time to make variable a rate of contribution of (i) the difference between the distances to the subject, and (ii) an amount of change in the image area to be cut out of the taken image.

An image taking method of adjusting by an image taking device a taken image according to a positional relationship with a subject, said image taking method comprising:

• taking an image of the subject by using a multifocal lens;
• extracting a reference figure contained in the image taken, and computing a distance from the image taking device to the subject based on a difference between the reference figure at a predetermined time and the reference figure at a present time;
• computing an image area to be cut out of the taken image based on the distance to the subject;
• and
• cutting-out a portion of the taken image according to a result of the computation of the image area,
• wherein said computing of the image area includes weighting a difference between the distance to the subject at the predetermined time and the distance to the subject at the present time to make variable a rate of contribution of (i) the difference between the distances to the subject, and (ii) an amount of change in the image area to be cut out of the taken image.

A program product that is embodied on a computer-readable recording medium and used for an image taking device which adjusts a taken image according to a positional relationship with a subject, said program product causing a computer to execute:

• taking an image of the subject by using a multifocal lens;
• extracting a reference figure contained in the image taken, and computing a distance from the image taking device to the subject based on a difference between the reference figure at a predetermined time and the reference figure at a present time;
• computing an image area to be cut out of the taken image on based on the distance to the subject;
• and
• cutting-out a portion of the taken image according to a result of the computation of the image area,
• wherein said computing of the image area includes weighting a difference between the distance to the subject at the predetermined time and the distance to the subject at the present time to make variable a rate of contribution of (i) the difference between the distances to the subject, and (ii) an amount of change in the image area to be cut out of the taken image.

An image taking device which adjusts a taken image according to a positional relationship with a subject, said image taking device comprising:

• an image taking unit operable to take an image of the subject by using a multifocal lens;
• a distance computation unit operable to (i) compute a difference between a size of an object at a predetermined time and a size of the object at a present time, by determining an optical flow indicating a movement of an observed point that belongs to the object, the object being contained in the image taken by said image taking unit, and (ii) compute an amount of change of a distance from said image taking device to the subject based on the computed difference between the sizes of the object;
• a focal length computation unit operable to compute a focal length of the multifocal lens based on the amount of the change of the distance to the subject;
• and
• a focal length control unit operable to control a focal length of the multifocal lens so that the focal length of the multifocal lens is adjusted to the focal length computed by said focal length computation unit,
• wherein said distance computation unit is operable to (i) judge which state among states including divergent, steady and convergent represents each optical flow of a plurality of optical flows, by judging, for the optical flows, increasing or decreasing of a distance from each centroid of a plurality of the observed points to the observed point, the optical flows indicating movements of the plurality of the observed points that belong to the object;
• (ii) extract, from the judged optical flows, only optical flows that are in a state represented by most optical flows, (iii) determine, for the extracted optical flows, a difference between a distance from the centroid to the observed point at the predetermined time and at the present time, and (iv) compute an average value of the determined differences as the amount of the change, and
• said focal length computation unit is operable to weight the amount of the change of the distance to make variable a rate of contribution of (i) the difference between the distances to the subject, and (ii) an amount of change in the focal length of the multifocal lens.

An image taking method of adjusting by an image taking device a taken image according to a positional relationship with a subject, said image taking method comprising:

• taking an image of the subject by using a multifocal lens;
• computing a difference between a size of an object at a predetermined time and a size of the object at a present time, by determining an optical flow indicating a movement of an observed point that belongs to the object, the object being contained in the image taken, and computing an amount of change of a distance from the image taking device to the subject based on the computed difference between the sizes of the object;
• computing a focal length of the multifocal lens based on the amount of the change of the distance to the subject;
• and
• controlling a focal length of the multifocal lens so that the focal length of the multifocal lens is adjusted to the focal length computed,
• wherein said computing of the difference and said computing of the among of the change of the distance includes (i) judging which state among states including divergent, steady and convergent represents each optical flow of a plurality of the optical flows, by judging, for the optical flows, increasing or decreasing of a distance from each centroid of a plurality of the observed points to the observed point, the optical flows indicating movements of the plurality of the observed points that belong to the object;
• (ii) extracting, from the judged optical flows, only optical flows that are in a state represented by most optical flows, (iii) determining, for the extracted optical flows, a difference between a distance from the centroid to the observed point at the predetermined time and at the present time, and (iv) computing an average value of the determined differences as the amount of the change, and
• said computing of the focal length includes weighting the amount of the change of the distance to make variable a rate of contribution of (i) the difference between the distances to the subject, and (ii) an amount of change in the focal length of the multifocal lens.

A program product that is embodied on a computer-readable recording medium and used for an image taking device which adjusts a taken image according to a positional relationship with a subject, said program product causing a computer to execute:

• taking an image of the subject by using a multifocal lens;
• computing a difference between a size of an object at a predetermined time and a size of the object at a present time, by determining an optical flow indicating a movement of an observed point belong to the object, the object being contained in the image taken in said taking, and computing an amount of change of a distance from the image taking device to the subject based on the computed difference between the sizes of the object;
• computing a focal length of the multifocal lens based on the amount of the change of the distance to the subject;
• and
• controlling a focal length of the multifocal lens so that the focal length of the multifocal lens is adjusted to the focal length computed in said computing of the focal length,
• wherein said computing of the difference and said computing of the among of the change of the distance includes (i) judging which state among states including divergent, steady and convergent represents each optical flow of a plurality of optical flows of the optical flows, by judging, for the optical flows, increasing or decreasing of a distance from each centroid of a plurality of the observed points to the observed point, the optical flows indicating movements of the plurality of the observed points that belong to the object;
• (ii) extracting, from the judged optical flows, only optical flows that are in a state represented by most optical flows, (iii) determining, for the extracted optical flows, a difference between a distance from the centroid to the observed point at the predetermined time and at the present time, and (iv) computing an average value of the determined differences as the amount of the change, and
• said computing of the focal length includes weighting the amount of the change of the distance to make variable a rate of contribution of (i) the difference between the distances to the subject, and (ii) an amount of change in the focal length of the multifocal lens.

An image taking device which adjusts a taken image according to a positional relationship with a subject, said image taking device comprising:

• an image taking unit operable to take an image of the subject by using a multifocal lens;
• a distance computation unit operable to (i) compute a difference between a size of an object at a predetermined time and a size of the object at a present time, by determining an optical flow indicating a movement of an observed point that belongs to the object, the object being contained in the image taken by said image taking unit, and (ii) compute an amount of change of a distance from said image taking device to the subject based on the computed difference between the sizes of the object;
• a cut-out area computation unit operable to compute an image area to be cut out of the taken image based on the amount of the change of the distance to the subject;
• and
• an image cut-out unit operable to cut out a portion of the taken image according to a result of the computation by said cut-out area computation unit,
• wherein said distance computation unit is operable to (i) judge which state among states including divergent, steady and convergent represents each optical flow of a plurality of the optical flows, by judging, for the optical flows, increasing or decreasing of a distance from each centroid of a plurality of the observed points to the observed point, the optical flows indicating movements of the plurality of the observed points that belong to the object;
• (ii) extract, from the judged optical flows, only optical flows that are in a state represented by most optical flows, (iii) determine, for the extracted optical flows, a difference between a distance from the centroid to the observed point at the predetermined time and at the present time, and (iv) compute an average value of the determined differences as the amount of the change, and
• said cut-out area computation unit is operable to weight the amount of the change of the distance to the subject at the present time to make variable a rate of contribution of (i) the difference between the distances to the subject, and (ii) an amount of change in the image area to be cut out of the taken image.

An image taking method of adjusting by an image taking device a taken image according to a positional relationship with a subject, said image taking method comprising:

• taking an image of the subject by using a multifocal lens;
• computing a difference between a size of an object at a predetermined time and a size of the object at a present time, by determining an optical flow indicating a movement of an observed point belong to the object, the object being contained in the image taken, and computing an amount of change of a distance from the image taking device to the subject based on the computed difference between the sizes of the object;
• computing an image area to be cut out of the taken image based on the amount of the change of the distance to the subject;
• and
• cutting-out a portion of the taken image according to a result of the computation in said computing of the image area,
• wherein said computing of the difference and said computing of the amount of the change of the distance includes (i) judging which state among states including divergent, steady and convergent represents each optical flow of a plurality of optical flows, by judging, for the optical flows, increasing or decreasing of a distance from each centroid of a plurality of the observed points to the observed point, the optical flows indicating movements of the plurality of the observed points that belong to the object;
• (ii) extracting, from the judged optical flows, only optical flows that are in a state represented by most optical flows, (iii) determining, for the extracted optical flows, a difference between a distance from the centroid to the observed point at the predetermined time and at the present time, and (iv) computing an average value of the determined differences as the amount of the change, and
• said computing of the image area includes weighting the amount of the change of the distance to the subject at the present time to make variable a rate of contribution of (i) the difference between the distances to the subject, and (ii) an amount of change in the image area to be cut out of the taken image.

A program product that is embodied on a computer-readable recording medium and used for an image taking device which adjusts a taken image according to a positional relationship with a subject, said program product causing a computer to execute:

• taking an image of the subject by using a multifocal lens;
• computing a difference between a size of an object at a predetermined time and a size of the object at a present time, by determining an optical flow indicating a movement of an observed point belong to the object, the object being contained in the image taken, and computing an amount of change of a distance from the image taking device to the subject based on the computed difference between the sizes of the object;
• computing an image area to be cut out of the taken image based on the amount of the change of the distance to the subject;
• and
• cutting-out a portion of the taken image according to a result of the computation in said computing of the image area,
• wherein said computing of the difference and said computing of the amount of the change of the distance includes (i) judging which state among states including divergent, steady and convergent represents each optical flow of a plurality of the optical flows, by judging, for the optical flows, increasing or decreasing of a distance from each centroid of a plurality of the observed points to the observed point, the optical flows indicating movements of the plurality of the observed points that belong to the object;
• (ii) extracting, from the judged optical flows, only optical flows that are in a state represented by most optical flows, (iii) determining, for the extracted optical flows, a difference between a distance from the centroid to the observed point at the predetermined time and at the present time, and (iv) computing an average value of the determined differences as the amount of the change, and
• said computing of the image area includes weighting the amount of the change of the distance to the subject at the present time to make variable a rate of contribution of (i) the difference between the distances to the subject, and (ii) an amount of change in the image area to be cut out of the taken image.