Method and system for image construction using multiple exposures
View Patent ↗A motion sensor is used to sense the movement of the camera during an exposure period. The camera has an image sensor to form one or more exposures. When the movement is within a certain range, the exposures are used to provide one or more frames so that an image can be constructed based on the frames. In one embodiment, the exposure period is divided into several short intervals in order to capture several image frames and only the image frames captured when the position of the camera is within a predetermined range are used to form the final image. The exposure time for each frame is small in order to reduce the motion blur degradation of the individual frames. If the camera is stable and substantially stationary relative to the scene, then all or many of the shorter frames are used to form the final image.
1. A method comprising:
exposing a projected image on an image sensor of an imaging system during at least part of an exposure period for attaining at least two exposures;
sensing movement of the imaging system, during the exposure period, in order to determine an amount of movement of the imaging system relative to an initial position of the imaging system in the exposure period; and
constructing an image based on at least a first exposure and a second exposure, wherein the first exposure is attained during a first time period, within the exposure period, in which the determined amount of movement of the imaging system is within a predetermined movement range relative to the initial position of the imaging system, the second exposure is attained during a second time period, within the exposure period, in which the determined amount of movement of the imaging system is within the predetermined movement range relative to the initial position of the imaging system, and between the first time period and the second time period there is a third time period in which the determined amount of movement of the imaging system is outside the predetermined movement range relative to the initial position of the imaging system.
2. A method according to claim 1 , wherein the first exposure and the second exposure, attained when the determined amount of movement of the imaging system is within the predetermined movement range relative to the initial position of the imaging system, form a single image frame during the exposure period, said method further comprising:
capturing the single image frame after the exposure period for constructing the acquired image.
3. A method according to claim 1 , wherein the first exposure and the second exposure, attained when the determined amount of movement of the imaging system is within the predetermined movement range relative to the initial position of the imaging system, separately form at least two image frames during the exposure period, said method further comprising:
capturing the at least two image frames at least during the exposure period for constructing the acquired image.
4. A method according to claim 1 , wherein the exposure period is divided into a plurality of shorter time periods and wherein the first exposure, attained during the first time period, forms a first image frame; and the second exposure, attained during the second time period, forms a second image frame, said method further comprising:
capturing said first and second image frames during the exposure period; and
selecting at least the first image frame and the second image frame for use in constructing the image.
5. A method according to claim 1 , further comprising
preventing the projected image from reaching the image sensor, during the third time period, when the determined amount of movement of the imaging system is outside the predetermined movement range relative to the initial position of the imaging system.
6. A method according to claim 1 , wherein the image sensor comprises an array of pixels, each pixel having a pixel area, and the predetermined movement range is determined based on one or more pixel areas.
7. A method according to claim 1 , wherein the imaging system comprises an optical system for providing the projected image on the image sensor, and the predetermined movement range is determined based on a focal distance of the optical system.
8. A method according to claim 1 , wherein the predetermined movement range is determined based on brightness of at least part of light forming the projected image.
9. An imaging system comprising:
an image sensor configured to attain at least a first exposure and a second exposure during an exposure period;
a movement sensor configured to sense movement of the imaging system, during the exposure period, in order to enable an amount of movement of the imaging system to be determined, relative to an initial position of the imaging system in the exposure period; and
a processor configured to construct an image based on at least the first exposure and the second exposure, wherein the first exposure is attained during a first time period, within the exposure period, in which the determined amount of movement of the imaging system is within a predetermined movement range relative to the initial position of the imaging system, the second exposure is attained during a second time period, within the exposure period, in which the determined amount of movement of the imaging system is within the predetermined movement range relative to the initial position of the imaging system, and between the first time period and the second time period there is a third time period in which the determined amount of movement of the imaging system is outside the predetermined movement range relative to the initial position of the imaging system.
10. An imaging system according to claim 9 , wherein the first exposure and the second exposure, attained when the determined amount of movement of the imaging system is within the predetermined movement range relative to the initial position of the imaging system, form a single image frame during the exposure period, and wherein the image is constructed based on the single image frame captured after the exposure period.
11. An imaging system according to claim 9 , wherein the first exposure and the second exposure, attained when the determined amount of movement of the imaging system is within the predetermined movement range relative to the initial position of the imaging system, separately form at least two image frames during the exposure period, and wherein the image is constructed based on the at least two image frames captured at least during the exposure period.
12. An imaging system according to claim 9 , wherein the image sensor is configured to divide the exposure period into a plurality of shorter time periods and the first exposure, attained during the first time period, forms a first image frame; and the second exposure, attained during the second time period, forms a second image frame, and wherein the processor is configured to capture the first and second and third image frames during the exposure period, configured to select the first image frame and the second image frame for use in constructing the image.
13. An imaging system according to claim 9 , further comprising
an optical system for providing a projected image on the image sensor so as to allow the image sensor to attain the first exposure and the second exposure during the exposure period.
14. An imaging system according to claim 13 , further comprising
a shutter, positioned in relationship to the optical system, configured to prevent the projected image from reaching the image sensor during the third time period, when the determined amount of movement of the imaging system is outside the predetermined movement range relative to the initial position of the imaging system.
15. An imaging system according to claim 9 , further comprising
an electronic circuit configured to prevent the image sensor from attaining the third exposure during the third time period, when the determined amount of movement of the imaging system is outside the predetermined movement range relative to the initial position of the imaging system.
16. An imaging system according to claim 9 , wherein the movement sensor provides a signal to indicate that the determined amount of movement of the imaging system is within the predetermined movement range so as to cause the image sensor to attain said first exposure during the first time period and so as to cause the image sensor to attain said second exposure during the second time period.
17. An imaging system, comprising:
means for sensing an image;
means for exposing a projected image on the image sensing means during an exposure period so as to allow the image sensing means to attain at least two exposures;
means for sensing movement of the imaging system, during the exposure period, in order to determine an amount of movement of the imaging system relative to an initial position of the imaging system in the exposure period; and
means for constructing an image based on at least a first exposure and a second exposure, wherein the first exposure is attained during a first time period, within the exposure period, in which the determined amount of movement of the imaging system is within a predetermined movement range relative to the initial position of the imaging system, the second exposure is attained during a second time period, within the exposure period, in which the determined amount of movement of the imaging system is within the predetermined movement range relative to the initial position of the imaging system, and between the first time period and the second time period there is a third time period in which the determined amount of movement of the imaging system is outside the predetermined movement range relative to the initial position of the imaging system.
18. An imaging system according to claim 17 , further comprising means for capturing at least two image frames for constructing the acquired image.
19. An imaging system according to claim 18 , further comprising:
means for selecting the captured image frames for constructing the acquired image.
20. An imaging system according to claim 17 , further comprising:
means for preventing the projected image from forming an exposure, during the third time period, when the determined amount of movement of the imaging system is outside the predetermined movement range relative to the initial position of the imaging system.