Imaging device and imaging method for correcting effects of motion on a captured image
A wearable camera that is an imaging device includes a sensing unit that senses motion of a camera, and a prediction unit that calculates a pixel shift distance (d) between frames based on the results of the sensing. The prediction unit obtains a position (p 1 ′) by moving a feature point (p 1 ) extracted from the previous frame image by the pixel shift distance (d), and the setting unit sets a window (w 4 ) having a position (p 1 ′) as the center in the current frame image (F t+1 ). A search unit searches the window (w 4 ) and detects a feature point (q 1 ) corresponding to the feature point (p 1 ).
1. An imaging device, comprising:
an imaging unit operable to capture an image of an object;
a sensing unit operable to sense physical motion of the imaging unit;
an extraction unit operable to extract a feature point from a first frame image;
a prediction unit operable to predict, according to the sensed physical motion, a position in which the feature point extracted from the first frame image is to appear in a second frame image that follows the first frame image after a fixed number of frames;
a setting unit operable to set a window in the second frame image according to the position predicted by the prediction unit;
a search unit operable to search in the set window of the second frame image for a feature point corresponding to the feature point extracted from the first frame image; and
a frame rate change unit operable to change the frame rate of the imaging unit to a higher value when the amount of the physical motion sensed by the sensing unit is greater than or equal to a predetermined threshold, wherein
the setting unit is further operable to change a size of the set window in proportion to the amount of the physical motion sensed by the sensing unit.
2. The imaging device of claim 1 , wherein
the setting unit sets the window so as to include the position predicted by the prediction unit.
3. The imaging device of claim 1 , wherein
the setting unit sets the window so that the position predicted by the prediction unit is in a center of the window.
4. The imaging device of claim 1 wherein
the setting unit changes the size of the window when the amount of the physical motion sensed by the sensing unit is larger than a preset value.
5. An imaging device, comprising:
an imaging unit operable to capture an image of an object;
a sensing unit operable to sense physical motion of the imaging unit;
an extraction unit operable to extract a feature point from a first frame image;
a prediction unit operable to predict, according to the sensed physical motion, a position in which the feature point extracted from the first frame image is to appear in a second frame image that follows the first frame image after a fixed number of frames;
a setting unit operable to set a window in the second frame image according to the position predicted by the prediction unit; and
a search unit operable to search in the set window of the second frame image for a feature point corresponding to the feature point extracted from the first frame image, wherein
the setting unit sets the window so that a center thereof is a midpoint between a position, in the second frame image, corresponding to the position of the feature point extracted from the first frame image and the position predicted by the prediction unit.
6. The imaging device of claim 5 further comprising:
a frame rate change unit operable to change the frame rate of the imaging unit to a higher value when the amount of the physical motion sensed by the sensing unit is greater than or equal to a predetermined threshold.
7. The imaging device of claim 6 , wherein
the frame rate change unit is further operable to change the frame rate to a first value when the amount of the motion sensed by the sensing unit is greater than or equal to the predetermined threshold, and change the frame rate to a second value that is higher than the first value when the amount of the motion sensed by the sensing unit is greater than or equal to a second threshold that is higher than the predetermined threshold.
8. The imaging device of claim 6 , wherein
the larger the physical motion sensed by the sensing unit, the higher the frame rate change unit changes the frame rate.
9. The imaging device of claim 6 further comprising:
a shutter speed change unit operable to change a shutter speed of the imaging unit to a higher value when the amount of the physical motion sensed by the sensing unit is greater than or equal to a predetermined threshold.
10. The imaging device of claim 9 further comprising:
a film speed change unit operable to change a film speed of the imaging unit to a higher value when the physical motion sensed by the sensing unit is greater than or equal to a predetermined threshold.
11. The imaging device of claim 5 , wherein
the sensing unit is composed of at least one of an angular speed sensor and an acceleration sensor.
12. An imaging device, comprising:
an imaging unit operable to capture an image of an object;
a sensing unit operable to sense physical motion of the imaging unit;
an extraction unit operable to extract a feature point from a first frame image;
a prediction unit operable to predict, according to the sensed physical motion, a position in which the feature point extracted from the first frame image is to appear in a second frame image that follows the first frame image after a fixed number of frames;
a setting unit operable to set a window in the second frame image according to the position predicted by the prediction unit;
a search unit operable to search in the set window of the second frame image for a feature point corresponding to the feature point extracted from the first frame image; and
a frame change unit operable to change the frame rate of the imaging unit to a higher value when the amount of the physical motion sensed by the sensing unit is greater than or equal to a predetermined threshold, wherein
the frame rate change unit performs an operation to change the frame rate at a predetermined time interval that is longer than a time interval between frame images.
13. An imaging device, comprising:
an imaging unit operable to capture an image of an object;
a sensing unit operable to sense physical motion of the imaging unit;
an extraction unit operable to extract a feature point from a first frame image;
a prediction unit operable to predict, according to the sensed physical motion, a position in which the feature point extracted from the first frame image is to appear in a second frame image that follows the first frame image after a fixed number of frames;
a setting unit operable to set a window in the second frame image according to the position predicted by the prediction unit; and
a search unit operable to search in the set window of the second frame image for a feature point corresponding to the feature point extracted from the first frame image,
wherein the setting unit sets an entirety of the second frame image as a search range once per a predetermined number of frames.
14. An imaging method comprising the steps of:
capturing an image of an object with use of an imaging unit;
sensing physical motion of the imaging unit;
extracting a feature point from a first frame image;
predicting, according to the sensed physical motion, a position in which the feature point extracted from the first frame image is to appear in a second frame image that follows the first frame image after a fixed number of frames;
setting a window in the second frame image according to the position predicted by the prediction step; and
searching in the set window of the second frame image for a feature point corresponding to the feature point extracted from the first frame image, wherein
the setting step sets the window so that a center thereof is a midpoint between a position, in the second frame image, corresponding to the position of the feature point extracted from the first frame image and the position predicted by the prediction step.