Embodiments are generally related to image capture devices and, more particularly, are related to a system and method for detecting image capture device movement.
Image capture devices may employ various devices to sense movement of the image capture device during image capture. Based upon the received information corresponding to movement, image data and/or image capture device components may be adjusted to result in capture of higher quality images.
A variety of sources may cause movement of the image capture device. For example, a photographer's hand may shake while the photographer is trying to capture an image. Or, the photographer may be afflicted with a physical disability or illness. Environmental factors such as wind may cause the movement. Or, the photographer and the image capture device may be in a vehicle moving over a rough surface, in an airplane traveling through rough weather, or on a boat in choppy water.
In some image capture devices, physical devices are employed to detect movement. Such physical devices provide information to a processing system that then generate instructions so that the image data and/or image capture device components may be adjusted. However, such physical devices may be limited by their number, cost and size. For example, a relatively large gyroscope may be difficult to place in a desired location within the image capture device. Also, cost considerations may limit the number of gyroscopes. Finally, the number of gyroscopes may be limited due to the desirability of limiting the overall size and/or cost of the image capture device.
In other image capture devices, an image is captured and then data corresponding to the captured image is analyzed to determine movement. In some, a series of successive images are analyzed. To save time and computational power, some image capture devices may capture and analyze smaller images or partial images having less data that a full sized image. However, in these image capture devices, image data analysis requires time for image data capturing and image data processing, and furthermore may require computational power that may place additional requirements on the processing device used in the image capture device.
One embodiment may comprise a first dual-axis linear accelerometer residing in the image capture device that senses a first acceleration in a first direction and that senses a first orthogonal acceleration in an orthogonal direction, a second dual-axis linear accelerometer residing in the image capture device that senses a second acceleration in the first direction and that senses a second orthogonal acceleration in the orthogonal direction, a processor that receives information from the first dual-axis linear accelerometer and the second dual-axis linear accelerometer such that the movement of the image capture device is determined.
Another embodiment is a method comprising sensing a first acceleration in a first direction and a first orthogonal acceleration in an orthogonal direction, sensing a second acceleration in the first direction and a second orthogonal acceleration in the orthogonal direction, determining a difference in acceleration between the first acceleration and the second acceleration, determining a difference in orthogonal acceleration between the first orthogonal acceleration and the second orthogonal acceleration, and determining the movement of the image capture device based upon the determined difference in acceleration and the determined difference in orthogonal acceleration.
The components in the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding parts throughout the several views.
The acceleration detection system 100 (
A dual-axis linear accelerometer is configured to detect acceleration concurrently in two directions, the directions being at right angles (orthogonal) to each other. In a MEMS (micro-electro-mechanical system) device, the dual-axis linear accelerometer is constructed using solid state chip fabrication technology that enables fabrication of a relatively small physical device that detects acceleration. One type of MEMS-based dual-axis linear accelerometer employs one or more physical members that move when the dual-axis linear accelerometer body structure is subjected to an acceleration. Changes in capacitance between the physical member(s) that moves and a stationary member is detectable. The changes in capacitance can be measured to generate one or more corresponding signals. Analysis of the signals allow a determination of the acceleration.
In addition to the lens 110, an image capture device 102 comprises many other components, such as a body 112, a viewing lens 114, and a variety of image capture device operation controls. One illustrative controller [assuming the image capture device 102 is a digital camera having a display (not shown) and other related features] is a mode selection actuator 116 that, when rotated into various positions, controls such functions as image capture mode, preview mode, display mode and/or menu set mode. Another illustrative controller is the shutter button 118, which when actuated by depression by the user, causes image capture. In some types of digital or film-based image capture devices 100, partial depression of the shutter button 118 causes the image capture device 102 to operate in an automatic focus mode such that the lens 110 is adjusted to bring an object of interest into focus onto the image capture medium (not shown) residing in the image capture device 102.
In one embodiment, detected acceleration is used to compute movement information corresponding to rotational movement vector 104 along the X axis, rotational movement vector 106 along the Y axis, and rotational movement vector 108 along the Z axis. The illustrated X, Y and Z axes, and their associated rotational vectors 104, 106 and 108, respectively, are used for illustration purposes. The X, Y and Z axis are illustrated as being referenced with respect to the image capture device lens 110. It is appreciated that any other reference point on or within the image capture device 102 could have been used for illustration purposes. Furthermore, other coordinate systems may be used, such a polar coordinate system or other suitable coordinate system, to determine movement of the image capture device 102.
Axis Z, in the exemplary image capture device 102 of
The aft dual-axis linear accelerometer 202 resides in a location in a rear portion of the image capture device 102. In this exemplary embodiment, one axis of the aft dual-axis linear accelerometer 202 is oriented such that linear acceleration along the XA axis is detected (wherein the XA axis corresponds to the X axis of
The fore dual-axis linear accelerometer 204 resides in a location in a front portion of the image capture device 102. In this exemplary embodiment, one axis of the fore dual-axis linear accelerometer 204 is oriented such that linear acceleration along the XF axis is detected (wherein the XF axis corresponds to the X axis of
The terms “aft” and “fore” are arbitrarily defined herein to identify and describe relative location of the dual-axis linear accelerometers 202 and 204. As in a ship, the term “aft” corresponds to the rear or back portion of the ship. Similarly, the term “fore” corresponds to the front or leading portion of the ship. In the simplified embodiment of the image capture device 102 of
Also, the fore dual-axis linear accelerometer 204 is illustrated as residing within the lens 110. In other embodiments, the fore dual-axis linear accelerometer 204 may reside in a front portion of the body 112. These embodiment variations are described in greater detail below.
Summarizing the exemplary embodiment of
For example, reference point 302 may correspond to a known point associated with the image capture medium. If the image capture device embodiment compensates for detected movement by moving the image capture medium, the nature of the compensating movement of the image capture medium may be based upon the determined movement of reference point 302. As another example, reference point 302 may correspond to a known point associated with the lens 110 (
The dual-axis linear accelerometers 202 and 204 are oriented with respect to each other by a known distance and orientation, illustrated by vector 304. The aft dual-axis linear accelerometer 202 and the reference point 302 are oriented with respect to each other by another known distance and orientation, illustrated by vector 306. The fore dual-axis linear accelerometer 204 and the reference point 302 are oriented with respect to each other by another known distance and orientation, illustrated by vector 308. The distance and orientation of vectors 304, 306 and 308 may be described using any suitable vector coordinate system, such as, but not limited to, polar coordinates or Cartesian coordinates.
When the image capture device is moved in a direction along its respective X axis (
Accordingly, a rotational vector 310 (about the Y axis) associated with the aft dual-axis linear accelerometer 202 may be determined. Similarly, a rotational vector 312 (about the Y axis) associated with the fore dual-axis linear accelerometer 204 may be determined. Because the vectors 304, 306 and 308 are known, a rotational vector 314 associated with the reference point 302 (about its respective Y axis) may be determined using known trigonometric, geometric and calculus algorithms. Furthermore, the acceleration of the reference point 302 along the X axis, denoted as XP is determinable using known trigonometric, geometric and calculus algorithms.
When the image capture device is moved in a direction along the Y axis (
Accordingly, a rotational vector 316 (about the X axis) associated with the aft dual-axis linear accelerometer 202 may be determined. Similarly, a rotational vector 318 (about the X axis) associated with the fore dual-axis linear accelerometer 204 may be determined. Because the vectors 304, 306 and 308 are known, a rotational vector 320 associated with the reference point 304 (about its respective X axis) may be determined using known trigonometric, geometric and calculus algorithms. Furthermore, the acceleration of the reference point 302 along the Y axis, denoted as YP is determinable using known trigonometric, geometric and calculus algorithms.
For convenience, an aft dual-axis linear accelerometer 202, fore dual-axis linear accelerometer 204, processor system 402, and memory 404 are illustrated as communicatively coupled to each other via communication bus 408 and connections 410, thereby providing connectivity between the above-described components. In alternative embodiments, the above-described components are connectivley coupled in a different manner than illustrated in
When the image capture device 102 (
Processor system 402 controls execution of a program, described herein as the acceleration analysis logic 406, employed by embodiments of the acceleration detection system 100. It is appreciated that any suitable processor system 402 may be employed in various embodiments of a acceleration detection system 100. Processor system 404 may be a specially designed and/or fabricated processing system, or a commercially available processor system. Non-limiting examples of commercially available processor systems include, but are not limited to, an 80×86 or Pentium series microprocessor from Intel Corporation, U.S.A., a PowerPC microprocessor from IBM., a Sparc microprocessor from Sun Microsystems, Inc., a PA-RISC series microprocessor from Hewlett-Packard Company, or a 68xxx series microprocessor from Motorola Corporation. In alternative embodiments, the parts of or all of the above described-components may be implemented as firmware or a combination of firmware and software.
Furthermore, the orientation of the dual-axis linear accelerometers 202 and 204 were described as being oriented along the X axis and the Y axis (
In the embodiment described in
Furthermore, some lens 110 may move. For example, some embodiments of an image capture device include retractable lens to facilitate a more compact configuration when not in use. The lens is configured to extend outward for operation. Other embodiments employ telescoping lens to adjust the field of view (magnification or the like) and/or autofocus lens to facilitate image focusing. Accordingly, when the lens 110 extends outward, a fore dual-axis linear accelerometer 204 residing in the lens 110 also moves to a more outward location, thereby increasing the distance of the vector 304 (and/or vector 308). Thus, more accurate detection of movement is facilitated based upon the geometry of the extended length of vector 304 (and/or vector 308). In such embodiments, other sensors may be required to determine the length and/or orientation vector 304 (and/or vector 308). Or, the change in length and/or orientation of the vector 304 (and/or vector 308) due to the extension of lens 110 may be known based upon the design of the image capture device 102.
For convenience, the movement of the image capture device 102 was described in terms of the X, Y, and Z axis (
As noted above, some types of image capture devices employ a system that moves the position of the image capture medium to compensate for movement. In alternative embodiments, the aft dual-axis linear accelerometer 202 is located on the image capture medium or the image capture medium movement actuator. Accordingly, more precise movement of the image capture movement may be determined. Also, the effectiveness of the compensation measures may be determined by such embodiments. For example, one embodiment may utilize a feedback loop that determines a differential signal. Thus, the image capture medium will be further stabilized by the associated stabilization control system.
With respect to the figures, the dual-axis linear accelerometers 202 and 204 may appear to be illustrated as being in alignment with each other along the Z axis. In some embodiments, the dual-axis linear accelerometers 202 and 204 may be offset from each other along the X axis and/or the Y axis. Accordingly, a known offset between the dual-axis linear accelerometers 202 and 204 along the X axis and/or the Y axis still allows a determination of the vectors 306, 306 and/or 308 (
The process begins at block 602. At block 604, a first acceleration is sensed in a first direction and a first orthogonal acceleration in an orthogonal direction. At block 606, a second acceleration is sensed in the first direction and a second orthogonal acceleration in the orthogonal direction. At block 608, a difference is determined in acceleration between the first acceleration and the second acceleration. At block 610, a difference is determined in orthogonal acceleration between the first orthogonal acceleration and the second orthogonal acceleration. At block 612, the movement of the image capture device is determined based upon the determined difference in acceleration and the determined difference in orthogonal acceleration. The process ends at block 614.
As described hereinabove, the dual-axis linear accelerometers 202 and 204 detect acceleration of the image capture device. In the various embodiments, the difference in acceleration along one of the axis corresponds can be determined, thereby yielding rotational acceleration along the axis. Integration over time of the rotational axis yields rotational velocity along the axis. Integration of the rotational velocity yields a change in rotational position.
Embodiments of the acceleration detection system 100 (
It should be emphasized that the above-described embodiments are merely examples of the disclosed system and method. Many variations and modifications may be made to the above-described embodiments. All such modifications and variations are intended to be included herein within the scope of this disclosure.
This application claims priority to copending U.S. provisional application entitled, “SYSTEM AND METHOD FOR DETECTING IMAGE CAPTURE DEVICE MOVEMENT WITH TWO DUAL AXIS LINEAR ACCELEROMETERS,” having ser. No. 60/614,311, filed Sep. 29, 2004, which is entirely incorporated herein by reference.
Number | Date | Country | |
---|---|---|---|
60614311 | Sep 2004 | US |