Patent Application
20070147817
This patent document contains information subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent, as it appears in the US Patent and Trademark Office files or records, but otherwise reserves all copyright rights whatsoever.
Aspects of the present disclosure relate to devices with camera features, including a divided autofocus search range.
Cameras or other devices with camera features include point-and-shoot digital or analog camera elements. A desired feature in these devices is the ability to switch the device from a “normal mode” (for focusing to objects located from a moderate distance from the camera to infinity) to a “macro mode” (for focusing to objects that are close to the camera, for example, as close as a few or several centimeters away). Many such devices have both a regular mode and a macro mode for auto focusing, so that the camera can automatically search within the selected focus mode. By limiting the focus search to the selected focus mode, focusing time can be saved. In addition, battery power can be saved, and the wear and tear on the lens positioning motor can be minimized.
Among cameras or devices with both regular and macro modes for autofocusing, if the user selects the wrong mode, it may not be possible for the camera to focus on the selected target object.
In accordance with one aspect of the present disclosure, apparatus are provided. The apparatus include an autofocus mechanism. The autofocus mechanism includes an autofocus preliminary operation mechanism and an autofocus continuation mechanism. The autofocus preliminary operation mechanism starts an autofocus of a lens assembly on a given target by first causing a focus quality determiner to determine the quality of focus of the lens assembly on the given target while the position of the lens unit is in one focus range. The autofocus of the lens assembly on the given target is started by causing an adjustment controller to effect a preliminary adjustment of the lens assembly position, within the same one focus range. The autofocus continuation mechanism automatically, upon a lack of successful focus by the autofocus preliminary operation mechanism while the lens assembly position is in the one focus range, continues an autofocus of the lens assembly on the given target by causing the adjustment controller to effect a continued adjustment of the lens assembly position from the one focus range to a different focus range. Meanwhile, the focus quality determiner continues to determine the quality of the focus.
Embodiments of the present disclosure are described in the detailed description which follows by reference to the noted drawings, by way of non-limiting example embodiments, in which like reference numerals represents similar parts throughout the several views of the drawings, and wherein:
The illustrated embedded device 10 includes a camera portion 11, mobile communications circuitry 28, and other elements 30. The camera portion 11 includes a lens assembly 12, an image sensor 14, image storage 16, and a camera control and functions unit 24. In addition, the camera portion 11 includes a lens positioning unit 22, a focus value determiner 18, and an autofocus processor 20.
The lens assembly 12 may include a lens assembly for allowing the taking of pictures, including both zoom and focus mechanisms. Image sensor 14 may include, for example, film, in the case of an analog camera, or a digital image sensor, for example, a CCD device (charged-coupled device). Image storage 16 may include local RAM (random access memory) memory provided within embedded device 10, and/or a removable memory device, for example, a memory card or a disk.
Focus value determiner 18 may include, for example, software or circuitry for calculating a focus value based upon a signal produced by image sensor 14.
Autofocus processor 20 causes the adjustment of the lens assembly positioning by sending a signal to lens positioning unit 22, to obtain a desired focus of the image as received by image sensor 14. Specifically, autofocus processor 20 may include a focus quality determiner 21 to determine a quality of focus of the lens assembly 12 on a given target, and an adjustment controller 23 to interact with lens positioning unit 22 to effect adjustment of the positioning of the lens assembly toward an improved quality of focus of the lens assembly 12 on the given target.
Camera control and functions units 24 may include, for example, various control and user interaction features, for example, switches, an image display, a display for displaying to users various icons and camera function controls, and mechanisms to receive inputs and cause the resulting adjustment of various settings and controls of the camera portion. Camera controls and functions unit 24 may be provided with an autofocus controls and functions unit 26. Autofocus controls and functions unit 26 may, for example, include mechanisms to cause certain actions when an autofocus attempt by autofocus processor 20 is successful or when an attempt is not (yet) successful or when an attempt fails. For example, when an autofocus is successful, a photograph function of the camera portion may be enabled. Instead, when the autofocus is not successful, the photograph function may be disabled. In addition, the user may be notified when the autofocus attempt was either successful or a failure. In addition, a mechanism may be provided to allow a user to override the focus control by autofocus processor 20, to allow the user to control the focus of the camera portion, and thus the positioning of lens assembly 12.
An autofocus attempt is successful when certain autofocus criteria are met, while an autofocus attempt is not successful when the autofocus criteria are not met.
Autofocus processor 22 may further include a preliminary operation mechanism 25 and a continuation mechanism 27 (which may include a focus mode changing mechanism). The preliminary operation mechanism 25 starts an autofocus of a lens assembly on a given target by first causing a focus quality determiner to determine the quality of focus of the lens assembly on the given target while the position of the lens unit is in one focus range (e.g., the current focus range; in the illustrated embodiment, the current focus range is one of a macro range and a normal range). In addition, the autofocus of the lens assembly on the given target is started by also causing an adjustment controller to effect a preliminary adjustment of the lens assembly position by the lens positioning unit 22, within the same one focus range.
The continuation mechanism 27 automatically, upon a lack of successful focus by the preliminary operation mechanism 25 while the lens assembly position is in the one focus range, continues an autofocus of the lens assembly on the given target, by causing the adjustment controller (the lens positioning unit 22 in the illustrated embodiment) to effect a continued adjustment of the lens assembly position from the one focus range (for example, a normal mode focus range) to a different focus range (for example, a macro mode focus range), while the focus quality determiner (which views a value provided by focus value determiner 18 in the illustrated embodiment) continues to determine the quality of focus of the camera portion of the device. Continuation mechanism 27 may be further provided with a range setting changer to change a focus range setting (i.e., the focus mode) of the camera. In the illustrated embodiment, the range setting is changed from one to the other of the macro and normal modes. This change is made when a final focus position is found during the continued autofocus operation.
The focus value determiner 18 may determine a focus value representative of the quality of focus of the lens assembly on a given target. This may be done in accordance with an active autofocus or a passive autofocus. With an active autofocus, the camera portion may emit a signal that bounces off of the object of the target object being photographed, and the signal, after bouncing back off of the target object, is detected by the camera portion of the device to determine the distance between the device and the target object. In the case of a passive autofocus, an internal computer analysis is carried out (by the focus value determiner 18 in the illustrated embodiment) to determine a focus value, e.g., based upon the contrast of the image.
The lens assembly, to effect changes in focus, is moved from a far end to a near end. The far end is the edge of the normal focus mode, which extents from a moderate location to the far end. The near end is the edge of the macro focus mode. Lens positioning unit 22 includes, among other elements, a lens assembly position sensor and a motor to move the lens assembly to positions ranging from the far end to the near end.
As noted above, the autofocus processor 20 may be provided with both a preliminary operation mechanism 25 to effect an autofocus attempt during a first focus range, and with a continuation mechanism 27 to automatically continue the autofocus of the lens assembly upon a lack of successful focus by the autofocus preliminary operation mechanism 25. The continuation of the autofocus of the lens assembly includes causing the lens positioning adjustment to continue into the other focus range of the lens assembly 12. Specifically, when the camera portion of the device is provided with macro and normal ranges, the continuation of the autofocus moves the focus range from one to the other of the macro and normal ranges.
Generally, in some cameras, an autofocus attempt will occur in only the current focus range. For example, if the camera is set in a macro mode, the autofocus attempt will only occur by testing lens positions within the macro range. If autofocus is now successful, the autofocus search stops. In contrast, in the embodiments illustrated herein, the autofocus will continue by determining if a suitable focus position can be found by moving the lens assembly to the other of the two focus ranges and continuing to determine an appropriate focus position of the lens assembly. The first case may be referred to as a “hard boundary”, wherein the autofocus function will stop and will not continue by moving the lens assembly into the other range. The second case may be referred to as a “soft boundary”, as the autofocus attempt will continue by moving the lens assembly into the other of the two focus ranges, i.e., by moving from one to the other of macro and normal ranges in the illustrated embodiment.
The illustrated embedded device 10 may include a user interface 32 as schematically shown in
An embodiment of this process is described as follows, with reference to the acts shown in
If there is a lack of successful focus, as determined at act 64, the process proceeds to act 68, at which point the boundary will be crossed, and the range of lens assembly positions will be changed from the first range (i.e., one of the macro and normal ranges) to the other range (i.e., the other of the macro and normal ranges).
At act 70, the lens is moved in a pattern throughout the second focus range, which corresponds to a focus mode that is not that set for the camera i.e., not chosen by the user. During this movement of the lens in the pattern throughout this other focus range, the focus values are monitored.
At act 72, a determination is made as to whether there is a lack of successful focus along the movement pattern at act 70. If there is a successful focus, the process proceeds to act 74, where the autofocus will be deemed to be complete, or where a fine search algorithm will be started. If there has not been a successful focus, as determined at act 72, the process will proceed to act 76, where the autofocus attempt will be deemed to have failed. At this point, the result of an autofocus failure, may, for example, be that the photographing function of the camera is disabled, and/or the user is notified of the failure of the autofocus, and/or the autofocus function is overwritten to allow the user to manually control the focusing of the lens assembly 12, or move the lens to a position corresponding to the maximum focus value throughout the search (before and after any boundary cross).
In one embodiment, autofocus criteria are considered to determine when an autofocus attempt has been successful for a given range of movement of the lens assembly. For example, three boundary-cross conditions may be considered: criterion A is true when the lens is moving toward the boundary, and the focus value as the lens reaches the boundary is larger than it is elsewhere in the current range of movement. Criterion B is true when all the focus values in the current range are all small, i.e., less than a predefined threshold value. Criterion C is true when the sampled focus values in the current range are “noisy,” e.g., the ratio of the smallest sampled focus value to the largest sampled focus value (FV-min/FV-max) is greater than another threshold value (e.g., 0.75). Using these criteria, in one example implementation of that embodiment, act 64 in the process shown in
The autofocus processor 20 may be provided with one or a plural set of algorithms for performing an autofocus, wherein the boundary between the macro and normal ranges of the lens position is a “soft” boundary, as described above. For example, the algorithm performed may effect a fast searching approach for searching for the focus position, with less of a concern for the manner in which the lens movement is stopped as it nears or arrives at the target position. Alternatively, the lens position may be moved at a medium speed, which results in less risk that the target position will be missed, as well as less complications associated with controlling the motor that moves the lens assembly. A slower, more exhaustive focus search algorithm may be employed as well.
The claims as originally presented, and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.
This application claims the benefit of provisional U.S. Application Ser. No. 60/722,882, entitled “SOFT BOUNDARY FOR DIVIDED AUTOFOCUS SEARCHING RANGE,” filed Sep. 29, 2005, assigned to the assignee of the present application, and incorporated herein by reference in its entirety for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 60722882 | Sep 2005 | US |
