Patent Publication Number: US-10313570-B2

Title: Dynamic conservation of imaging power

Description:
BACKGROUND 
     Imaging systems based on light waves are becoming more widely used for object detection as semiconductor processes have become faster to support such systems. Some imaging systems are capable of providing dozens of images per second, making such systems useful for object tracking as well. Due to their potentially small form factor and potentially high signal fidelity, some imaging systems are well suited for gesture control in many types of consumer devices (e.g., television, computers, tablets, smartphones, etc.). While the resolution of such imaging systems may vary, applications using these systems are able to take advantage of the speed of their operation. 
     Mobile devices such as notebook computers or smart phones are not easily adapted to using such imaging systems due to the power requirements of the imaging systems and the limited power storage capability of the mobile devices. The greatest contributors to the high power requirement of light-based imaging systems are the illumination source, which may be applied at a constant power level and/or constant frequency during operation and modulation functions. Further, such systems may be applied with a constant maximum lateral resolution (i.e., number of pixels) for best performance in worst case usage scenarios. 
     The power demands often exceed the power storage capabilities of mobile devices, diminishing the usefulness of the imaging systems as applied to the mobile devices. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The detailed description is set forth with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items. 
       For this discussion, the devices and systems illustrated in the figures are shown as having a multiplicity of components. Various implementations of devices and/or systems, as described herein, may include fewer components and remain within the scope of the disclosure. Alternately, other implementations of devices and/or systems may include additional components, or various combinations of the described components, and remain within the scope of the disclosure. 
         FIG. 1  is an illustration of an example application environment in which the described devices and techniques may be employed, according to an implementation. 
         FIG. 2  is a block diagram of example imaging system components, according to an implementation. 
         FIG. 3  is a state diagram of example operating modes and associated imaging parameters, according to an implementation. The state diagram also shows example triggers for switching between operating modes. 
         FIG. 4  is a flow diagram illustrating an example process for adjusting parameters of an imaging system, according to an implementation. 
     
    
    
     DETAILED DESCRIPTION 
     Overview 
     This disclosure is related to imaging systems (imaging systems using emitted electromagnetic (EM) radiation, for example) that are arranged to detect, recognize, and/or track objects and/or gestures in a predetermined area relative to the imaging systems. For example, an imaging system may be used to detect and recognize gestures of an object or a human hand, for instance, in an area near a computing device. The imaging system may recognize when the object or hand is making a gesture, and track the hand-gesture combination as a replacement for a mouse or other input to the computing device. 
     In one implementation, the imaging system uses time-of-flight principles, such as distance calculations of reflected light emissions, to detect, recognize, and/or track objects, such as a human hand or gestures, for example. Time-of-flight distance calculations may be based on receiving reflections of emitted EM radiation, as the EM radiation is reflected off objects in the predetermined area. For example, the distance calculations may be based on the speed of light and the travel time of the reflected EM radiation. 
     Such imaging systems can be well suited for gesture control, for example, many types of consumer devices (e.g., television, computers, tablet devices, smartphones, etc.) due to their potentially small form factor and potentially high signal fidelity. However, the power requirements of such imaging systems can make them prohibitive for use in mobile devices, which can have limited battery storage. In many cases, gesture tracking and control may not be required constantly, but rather when gestures are present in a “predefined area.” Accordingly, it may be useful to power down or deactivate some functions and/or portions of the imaging system when no gestures (e.g., object movement) are present in the predefined area. Thus, power can be conserved when the imaging system is in a “standby mode.” Then, when object movement is detected in the predefined area, the functions and/or portions of the imaging system can be partially or fully activated. 
     Representative implementations of devices and techniques provide adaptable settings for example imaging devices and systems. The adaptable settings may be associated with various operating modes of the imaging devices and systems and may be used to conserve power, making the imaging devices more adaptable for use in mobile devices, for example. Operating modes may be defined based on whether object movement is detected within a predetermined area. For example, one operating mode can be defined for a standby condition and another can be defined for an active condition. In one implementation, an imaging device captures images of a predefined area at intervals. Operating modes are defined based on whether a difference is detected between the images captured of the predetermined area, and whether the difference indicates object movement within the predefined area. 
     Operating modes may be associated with parameters such as power levels, modulation, duty cycles, and the like, of emitted EM radiation. Additionally, operating modes may be associated with parameters such as modulation, image capture rate, current detection, and the like of photosensitive pixels of an imaging device sensor. One or more parameters of the emitted EM radiation or of the pixels may be dynamically and automatically adjusted based on a present operating mode and subsequent operating modes. For example, a higher resolution mode may be used by an imaging system when object movement is detected and a lower resolution mode may be used when no object movement is detected. In various implementations, illumination parameters may be adjusted based on the operating modes as well. 
     Various implementations and arrangements for imaging systems, devices, and techniques are discussed in this disclosure. Techniques and devices are discussed with reference to example light-based imaging systems and devices illustrated in the figures. However, this is not intended to be limiting, and is for ease of discussion and illustrative convenience. The techniques and devices discussed may be applied to any of various imaging device designs, structures, and the like (e.g., radiation based, sonic emission based, particle emission based, etc.) and remain within the scope of the disclosure. 
     Implementations are explained in more detail below using a plurality of examples. Although various implementations and examples are discussed here and below, further implementations and examples may be possible by combining the features and elements of individual implementations and examples. 
     Example Imaging System Environment 
       FIG. 1  is an illustration of an example application environment  100  in which the described devices and techniques may be employed, according to an implementation. As shown in the illustration, an imaging system  102  may be applied with a computing device (“mobile device”)  104 , for example. The imaging system  102  may be used to detect movement of an object  106 , such as a human hand, for example, in a predetermined area  108 . In one implementation, the imaging system  102  is arranged to detect and/or recognize a gesture of the object or human hand  106 , and may be arranged to track the movement and/or gesture of the object or human hand  106  as a replacement for a mouse or other input device for the mobile device  104 . In an implementation, an output of the imaging system  102  may be presented or displayed on a display device  110 , for example (e.g., a mouse pointer or cursor). 
     In various implementations, the imaging system  102  may be integrated with the mobile device  104 , or may have some components separate or remote from the mobile device  104 . For example, some processing for the imaging system  102  may be located remotely (e.g., cloud, network, etc.). In another example, some outputs from the imaging system  102  may be transmitted, displayed, or presented on a remote device or at a remote location. 
     As discussed herein, a mobile device  104  refers to a mobile computing device such as a laptop computer, smartphone, or the like. Examples of a mobile device  104  may include without limitation mobile computing devices, laptop or notebook computers, handheld computing devices, tablet computing devices, netbook computing devices, personal digital assistant (PDA) devices, reader devices, smartphones, mobile telephones, media players, wearable computing devices, and so forth. The implementations are not limited in this context. Further, stationary computing devices are also included within the scope of the disclosure as a computing device  104 , with regard to implementations of an imaging system  102 . Stationary computing devices may include without limitation, stationary computers, personal or desktop computers, televisions, set-top boxes, gaming consoles, audio/video systems, appliances, and the like. 
     An example object  106  may include any item that an imaging system  102  may be arranged to detect, recognize, track and/or the like. Such items may include human body parts, such as all or a portion of a human hand, for example. Other examples of an object  106  may include a mouse, a puck, a wand, a controller, a game piece, sporting equipment, and the like. In various implementations, the imaging system  102  may also be arranged to detect, recognize, and/or track a gesture of the object  106 . A gesture may include any movement or position or configuration of the object  106  that is expressive of an idea. For example, a gesture may include positioning a human hand in an orientation or configuration (e.g., pointing with one or more fingers, making an enclosed shape with one or more portions of the hand, etc.) and/or moving the hand in a pattern (e.g., in an elliptical motion, in a substantially linear motion, etc.). Gestures may also be made with other objects  106 , when they are positioned, configured, moved, and the like. 
     The imaging system  102  may be arranged to detect, recognize, and/or track an object  106  that is within a predetermined area  108  relative to the mobile device  104 . A predetermined area  108  may be chosen to encompass an area that human hands or other objects  106  may be within, for example. In one case, the predetermined area  108  may encompass an area where hands may be present to make gestures as a replacement for a mouse or other input device. This area may be to the front, side, or around the mobile device  104 , for example. 
     The illustration of  FIG. 1  shows a predetermined area  108  as a cube-like area in front of the mobile device  104 . This is for illustration and discussion purposes, and is not intended to be limiting. A predetermined area  108  may be any shape or size, and may be chosen such that it will generally encompass desired objects when they are present, but not encompass undesired objects (e.g., other items that are not intended to be detected, recognized, tracked, or the like). In one implementation, the predetermined area  108  may comprise a one foot by one foot cube. In other implementations, the predetermined area  108  may comprise other shapes and sizes. 
     As discussed above, the techniques, components, and devices described herein with respect to an imaging system  102  are not limited to the illustration in  FIG. 1 , and may be applied to other imaging system and device designs and/or applications without departing from the scope of the disclosure. In some cases, additional or alternative components may be used to implement the techniques described herein. It is to be understood that an imaging system  102  may be implemented as stand-alone system or device, or as part of another system (e.g., integrated with other components, systems, etc.). 
     Example Imaging System 
       FIG. 2  is a block diagram showing example components of an imaging system  102 , according to an implementation. As shown in  FIG. 2 , an imaging system  102  may include an illumination module  202 , a modulation component  204 , a sensor module  206 , and a control module  208 . In various implementations, an imaging system  102  may include fewer, additional, or alternate components, and remain within the scope of the disclosure. One or more components of an imaging system  102  may be collocated, combined, or otherwise integrated with another component of the imaging system  102 . For example, in one implementation, the imaging system  102  may comprise an imaging device or apparatus. Further, one or more components of the imaging system  102  may be remotely located from the other(s) of the components. 
     If included in an implementation, the illumination module  202  is arranged to emit electromagnetic (EM) radiation (e.g., light radiation) to illuminate the predetermined area  108 , based on an operating mode of the system  102 . In an implementation, the illumination module  202  is a light emitter, for example. In various implementations, the light emitter comprises a light-emitting diode (LED), a laser emitter, or the like. In one implementation, the illumination module  202  illuminates the entire environment (e.g., the predetermined area  108 ) when active. In an alternate implementation, the illumination module  202  illuminates the environment in pulses, stages, or scans. 
     In various implementations, different forms of EM radiation may be emitted from the illumination module  202 . In some implementations, infrared light, or the like, is emitted. For example, the light radiation may comprise one or more modulated light pulses. The illumination module  202  may be switched on for a short interval, allowing the emitted light pulse(s) to illuminate the predetermined area  108 , including any objects  106  within the predetermined area  108 . Infrared light, for example, provides illumination to the predetermined area  108  that is not visible to the human eye, and so is not distracting. In other implementations, other types or frequencies of EM radiation may be emitted that provide visual feedback or the like. As mentioned above, in alternate implementations, other energy forms (e.g., radiation based, sonic emission based, particle emission based, etc.) may be emitted by the illumination module  202 . 
     In an implementation, the illumination module  202  is arranged to illuminate one or more objects  106  that may be present in the predetermined area  108 , to detect movement of the objects  106 . For example, the illumination module  202  is arranged to emit electromagnetic radiation to illuminate at least a portion of the predetermined area  108  based on an operating mode of the system. In one implementation, a parameter or characteristic of the output of the illumination module  202  (a light pulse, for example) is arranged to be automatically and dynamically adjusted based on whether movement of an object  106  is detected in the predetermined area  108 . For example, to conserve power, the power output or modulation of the illumination module  202  may be deactivated when no object movement is detected in the predetermined area  108  and activated when an object movement is detected in the predetermined area  108 . 
     If included in an implementation, the modulation component  204  is arranged to modulate the EM radiation emitted from the illumination module  202  and/or to modulate one or more photosensitive pixels of the sensor module  206 , based on an operating mode of the imaging system  102 . In one implementation, the modulation component  204  is arranged to correlate the modulation of the EM radiation with the modulation of the pixels of the sensor module  206  during time-of-flight operation (e.g., to calculate a distance of an object from the imaging system  102 , for example). In various implementations, the modulation component  204  may deactivate modulation of the EM radiation emitted from the illumination module  202  and/or deactivate modulation of one or more photosensitive pixels of the sensor module  206  when the system is in a standby mode (e.g., when no object  106  movement is detected in the predetermined area  108 ) and activate modulation of the EM radiation and/or activate modulation of one or more photosensitive pixels when the system is in an active mode (e.g., when object  106  movement is detected in the predetermined area  108 ). 
     In various implementations, as shown in  FIG. 2 , the sensor module  206  is included in an imaging system  102 . In one implementation, the sensor module  206  is arranged to receive reflected EM radiation from object(s)  106  in the predetermined area  108 . In an implementation, the sensor module  206  is comprised of multiple photosensitive pixels. In one example, each of the multiple pixels may be an individual image sensor. In such an example, a resulting image from the sensor module  206  may be a combination of the sensor images of the individual pixels. In an implementation, each of the plurality of photosensitive pixels are arranged to convert the reflection of the EM radiation into an electrical current signal. In various implementations, the current signals from the pixels may be processed into an image by one or more processing components (e.g., the control module  208 ). 
     In an implementation, the sensor module  206  is arranged to capture one or more images of the predetermined area  108 . For example, the sensor module  206  may capture a low-resolution image of the predetermined area  108  while in a standby mode and a higher-resolution, three-dimensional image of the predetermined area  108  while in an active mode. In various implementations, the sensor module  206  may be arranged to capture images of the predetermined area  108  at intervals (e.g., at 500 millisecond intervals, or the like, while in standby mode and at 16 millisecond intervals, or the like, while in the active mode, etc.) or at a particular frame rate (e.g., 2 fps, or the like, while in standby mode and at 60 fps, or the like, while in the active mode, etc.). Accordingly, in at least one implementation, the imaging system  102  uses a first frame rate for capturing an image while in the active mode and uses a second, lower frame rate for capturing an image while in the standby mode. 
     In an implementation, the sensor module  206  (or the individual pixels of the sensor module  206 ) provides a measure of the time for light radiation to travel from the illumination module  202 , to the object  106 , and back to the sensor module  206 . Accordingly, in such an implementation, the imaging system  102  comprises a three-dimensional gesture recognition system arranged to detect a gesture of an object  106  within the predetermined area  108  based on receiving a reflection of the light radiation and based on time-of-flight principles. 
     For example, in the implementation, the sensor module  206  is an image sensor arranged to detect an object  106  within the predetermined area  108  based on receiving the reflected EM radiation. The sensor module  206  can detect whether an object is in the predetermined area  108  based on the time that it takes for the EM radiation emitted from the illumination module  202  to be reflected back to the sensor module  206 . This can be compared to the time that it takes for the EM radiation to return to the sensor module  206  when no object is in the predetermined area  108 . 
     In an implementation, the sensor module  206  is arranged to recognize a gesture of an object  106  (such as a human hand, for instance) within the predetermined area  108  based on receiving the reflection of the light radiation. For example, the sensor module  206  can recognize a human hand, an object  106 , and/or a gesture based on the imaging of each individual pixel of the sensor module  206 . The combination of each pixel as an individual imaging sensor can result in an image of a hand, a gesture, and the like, based on reflection times of portions of the EM radiation received by the individual pixels. This, in combination with the frame rate of the sensor module  206 , allows tracking of the image of a hand, an object, a gesture, and the like. In other implementations, the sensor module  206  can recognize multiple objects, hands, and/or gestures with imaging from the multiple individual pixels. 
     In an implementation, a resolution of the sensor module  206  may be adjustable based on the operating mode of the imaging system  102 . For example, in a first operating mode, the sensor module may capture a low-resolution image of the predetermined area  108  (10×10 pixels, for example) to conserve energy when no object  106  movement is detected. In a second operating mode, the sensor module may capture a higher-resolution image of the predetermined area  108  (160×160 pixels, for example) for best performance when some object  106  movement is detected. In other implementations, other resolution values may be associated with the operating modes, or alternate operating modes. 
     In a further implementation, the sensor module  206  may perform binning of the pixels configured to receive the reflection of the EM radiation. For example, the binning may include combining a group of adjacent pixels and processing the group of pixels as single composite pixel. Increased pixel area may result in higher sensor-sensitivity, and therefore reduce the illumination demand, allowing a power reduction in the emitted EM radiation or operation in lower ambient light. This power reduction may be in the form of reduced peak power, reduced integration time, or the like. Further, image processing may be reduced with fewer pixels used, achieving additional power savings. 
     In one implementation, operating modes are defined for the imaging system  102  that are associated with the parameters, characteristics, and the like (e.g., power levels, modulation, etc.), for the output of the illumination module  202 , based on whether movement of an object  106  is detected in the predetermined area  108 .  FIG. 3  is a state diagram  300  showing two example operating modes and the associated imaging system  102  parameters, according to an implementation. The two operating modes are labeled “standby mode,” (i.e., first operating mode) meaning no object movement is detected in the predetermined area  108  and “active,” (i.e., second operating mode) meaning some movement of at least one object is detected in the predetermined area  108 . In alternate implementations, fewer, additional, or alternate operating modes may be defined and/or used by an imaging system  102  in like manner. 
     As shown in  FIG. 3 , the imaging system  102  may alternate between the operating modes (e.g., standby mode and active mode) based on whether object movement is detected within the predetermined area  108 . In various implementations, a time duration may also be used to determine a switch from one operating mode to the other operating mode. For example, in an implementation, the imaging system  102  may be set to the standby mode when no object movement is detected within the predetermined area  108  within a preset time duration (e.g., 500 milliseconds, or the like). 
     As shown in  FIG. 3 , in various implementations, one or more functions of the illumination module  202  of the imaging system  102  may be adjusted or deactivated to conserve power while the imaging system  102  is in the standby mode. For example, the illumination may be deactivated during image capture or it may be unmodulated during image capture. In another example, the illumination may be “flashed” during image capture while the imaging system  102  is in the standby mode. In other words, the illumination may be pulsed with one or more discontinuous pulses of light radiation as the sensor module  206  captures a low-resolution image, similar to a flash on a conventional still camera, for example. Further, such a flash pulse need not be modulated, conserving more power. 
     In an implementation, the imaging system  102  may capture a low-resolution image while illuminating the predetermined area  108  with a single illumination period. This is in contrast to capturing a higher-resolution image which may use more (e.g., in one example, approximately 4) illumination periods for a similar, but three-dimensional, capture. 
     Additionally, two or more adjustments to the illumination or the illumination module  202  may be combined to conserve power while the imaging system  102  is in the standby mode. In other implementations, additional or alternate functions of the illumination module  202  may be adjusted while in the standby mode. In various implementations, the control module  208  is arranged to adjust or deactivate the above functions of the illumination module  202  while in the standby mode. 
     Also as shown in  FIG. 3 , in various implementations, one or more functions of the illumination module  202  of the imaging system  102  may be activated while the imaging system  102  is in the active mode. For example, the illumination (i.e., light radiation) may be activated during image capture and it may be modulated during image capture. Further, the illumination may be at full power or full intensity during image capture while in the active mode. In other implementations, additional or alternate functions of the illumination module  202  may be activated while in the active mode. In various implementations, the control module  208  is arranged to adjust or activate the above functions of the illumination module  202  while in the active mode. 
     As shown in  FIG. 3 , in various implementations, one or more functions of the sensor module  206  (and/or the modulation component  204 ) of the imaging system  102  may be adjusted or deactivated to conserve power while the imaging system  102  is in the standby mode. For example, the sensor module  206  may capture a low-resolution image of the predetermined area  108 . For example, the low-resolution image may include an image captured with fewer pixels than an image captured in the active mode. In other examples, the low-resolution image may include a two-dimensional image, a gray-scale image, or the like (e.g., an intensity image), or a combination of the above. 
     In a further implementation, the sensor module  206  may be arranged to capture an image using unmodulated pixels. In other words, the modulation component  204  may be adjusted or deactivated with respect to the photosensitive pixels of the sensor module  206 . In one implementation, some or all of the pixels may be binned, as described above, while the imaging system  102  is in the standby mode. In another implementation, the sensor module  206  may be arranged to read a fraction of the current produced by the photosensitive pixels. In other words, a preset proportion of the electrical current generated by reflected light received by the pixels of the sensor module is read. 
     In one implementation, pixels having at least two sides or sections are used in the sensor module  206 . In the implementation, the sensor module  206  may be arranged to read from fewer than all of the sides or sections of the pixels. For example, in one implementation, the sensor module  206  may be arranged to read from one of the two or more sides or sections while the imaging system  102  is in the standby mode. Doing so can reduce the power consumption of the imaging system  102  while in standby mode. In alternate implementations, the sensor module  206  may be arranged to read from another fraction of the sides or sections of the pixels. 
     In one implementation, as discussed above, the sensor module  206  may be arranged to capture images at a lower frame rate while in the standby mode than a frame rate used for capturing images while in the active mode. Further, any or all of the sensor module  206  related functions may be adjusted in combination. In other implementations, additional or alternate functions of the sensor module  206  or modulation component  204  may be adjusted while in the standby mode. In various implementations, the control module  208  is arranged to adjust or deactivate these functions of the sensor module  206  and/or the modulation component  204  while in the standby mode. 
     Also as shown in  FIG. 3 , in various implementations, one or more functions of the sensor module  206  (and/or the modulation component  204 ) of the imaging system  102  may be activated while the imaging system  102  is in the active mode. For example, the sensor module  206  may capture a high-resolution image of the predetermined area  108  and/or a three-dimensional image of the predetermined area  108  while in the active mode. In one implementation, the imaging system  102  is arranged to perform three-dimensional imaging arranged to detect a gesture within the predetermined area  108 , based on time-of-flight principles, while in the active mode. 
     In one implementation, the sensor module  206  is arranged to capture an image using modulated pixels. In other words, the modulation component  204  may be adjusted or activated with respect to the photosensitive pixels of the sensor module  206 . In one implementation, some or all of the pixels may be used individually to increase or maximize the resolution of captured images, while the imaging system  102  is in the active mode. In another implementation, the sensor module  206  may be arranged to read the full current produced by the photosensitive pixels. In other words, a full value of the electrical current generated by reflected light received by the pixels of the sensor module is read. 
     In one implementation, where pixels having at least two sides or sections are used in the sensor module  206 , the sensor module  206  may be arranged to read from both or all of the sides or sections of the pixels. For example, in one implementation, the sensor module  206  may be arranged to read from all of the two or more sides or sections while the imaging system  102  is in the active mode. 
     In one implementation, as discussed above, the sensor module  206  may be arranged to capture images at a higher frame rate while in the active mode than a frame rate used for capturing images while in the standby mode. Further, any or all of the sensor module  206  related functions may be adjusted or activated in combination. In other implementations, additional or alternate functions of the sensor module  206  or modulation component  204  may be adjusted or activated while in the active mode. In various implementations, the control module  208  is arranged to adjust or activate the above functions of the sensor module  206  and/or modulation component  204  while in the active mode. 
     If included in an implementation, the control module  208  may be arranged to provide controls and/or processing to the imaging system  102 . For example, the control module  208  may control the operating modes of the imaging system  102 , control the operation of the other modules ( 202 ,  204 ,  206 ), and/or process the signals and information output by the other modules ( 202 ,  204 ,  206 ). In various implementations, the control module  208  is arranged to communicate with one or more of the illumination module  202 , modulation component  204 , and sensor module  206 . In some implementations, the control module  208  may be integrated into one or more of the other modules ( 202 ,  204 ,  206 ), or be remote to the modules ( 202 ,  204 ,  206 ). 
     In one implementation, the control module  208  is arranged to determine the operating mode of the imaging system  102  based on whether captured images indicate movement of an object  106  within the predetermined area  108 . In the implementation, the control module  208  is arranged to compare captured images (e.g., either low-resolution or high-resolution images) to determine any differences in the images. For example, in an implementation, the control module  208  compares an image of the predetermined area to a previously captured image of the predetermined area. If an object has moved during the time between the image captures, the later image may reflect the movement as a difference in the images. If no differences are detected in subsequent images, no object movement within the predetermined area  108  may be indicated. 
     Accordingly, in an implementation, the control module  208  is arranged to determine a difference between a low-resolution image or a higher-resolution image (depending on the operating mode at the time of capture) and a previously captured image of the predetermined area  108 , and to determine an operating mode of the imaging device or system  102  based on whether the difference (or lack of a difference) indicates object movement within the predetermined area  108 , within a preset time duration. As discussed with respect to the state diagram  300  in  FIG. 3 , the control module  208  switches or sets the imaging system  102  to the first operating mode when no object movement is detected within the predetermined area  108  within a preset time duration and the control module  208  switches or sets the imaging system  102  to the second operating mode when movement of an object  106  is detected within the predetermined area  108 . In alternate implementations, the control module  208  may be arranged to automatically switch the imaging system  102  between operating modes based on other triggers (e.g., thermal values, power levels, light conditions, etc.). 
     In an implementation, the control module  208  is arranged to detect, recognize, and/or track a gesture made by one or more hands, or by an object  106 . In various implementations, the control module  208  may be programmed to recognize some gestures and/or objects  106  and exclude others. The control module  208  may also be programmed to recognize and track certain gestures associated with inputs or commands to the mobile device  104 , and the like. In one example, the control module  208  sets the imaging system  102  to the second operating mode when tracking a gesture, to ensure the best performance, and provide the most accurate read of the gesture. 
     In various implementations, the control module  208  may be arranged to calculate a distance of the object  106  from the imaging system  102 , based on the measured time of the reflected EM radiation. Accordingly, the control module  208  may be arranged to convert the current signal output from the sensor module  206  (or from the pixels of the sensor module  206 ) to a distance of the object  106  from the imaging system  102 . Further, in an implementation, the control module  208  may be arranged to convert the current signal to a three-dimensional image of the object  106 . In one implementation, the control module  208  is arranged to output the calculated distance and/or the three-dimensional image of the object  106 . For example, the imaging system  102  may be arranged to output a distance, a three-dimensional image of the detected object  106 , tracking coordinates of the object  106 , and so forth, to a display device, to another system arranged to process the information, or the like. 
     In various implementations, additional or alternative components may be used to accomplish the disclosed techniques and arrangements. 
     Representative Process 
       FIG. 4  illustrates a representative process  400  for adjusting parameters of an imaging system (such as imaging system  102 ). The process  400  describes detecting movement of one or more objects (such as an object  106 ) in a predetermined area (such as predetermined area  108 ). One or more parameters of emitted electromagnetic (EM) radiation may be adjusted based on whether movement of an object is detected in the predetermined area. The process  400  is described with reference to  FIGS. 1-3 . 
     The order in which the process is described is not intended to be construed as a limitation, and any number of the described process blocks can be combined in any order to implement the process, or alternate processes. Additionally, individual blocks may be deleted from the process without departing from the spirit and scope of the subject matter described herein. Furthermore, the process can be implemented in any suitable materials, or combinations thereof, without departing from the scope of the subject matter described herein. 
     At block  402 , the process includes capturing a low-resolution image of a predetermined area with a three-dimensional imager in a first operating mode. For example, a low-resolution image may include a two-dimensional image, a gray-scale image, an image captured with fewer pixels, a combination of the above, or the like. 
     At block  404 , the process includes capturing a higher-resolution, three-dimensional image of the predetermined area with the three-dimensional imager in a second operating mode. For example, the higher-resolution image may be captured using a greater number of pixels than the low-resolution image. Additionally, the higher-resolution image may be three dimensional, based on time-of-flight image capture techniques. 
     In various implementations, image capture (low or higher-resolution) may include emitting electromagnetic (EM) radiation to illuminate a predetermined area. In some implementations, the image capture is performed in ambient light (e.g., the natural light of the environment), without active illumination. In an implementation, where the ambient light is not sufficient for the image capture, the EM radiation may be “flashed” using one or more discontinuous impulses during the image capture. 
     In one example, the EM radiation may be emitted by an emitter (such as illumination module  202 , or the like) comprising an LED or laser emitter, for example. In some implementations, the EM radiation may be modulated light. For example, the light may be modulated using a modulation component (such as modulation component  204 ) and may be modulated in correlation to the modulation of one or more photosensitive pixels of the imaging device. In one implementation, the light is not modulated when the imaging system is operated in the standby mode. In various implementations, the predetermined area may be relative to a computing device (such as mobile device  104 ), such as to provide an input to the computing device, for example. 
     In various implementations, the process includes receiving reflected EM radiation by an imaging sensor (such as sensor module  206 ) to capture the images. The imaging sensor may be comprised of one or more photosensitive pixels, for example. The EM reflection may be received by the imaging sensor via optics, a receiver, an antenna, or the like, for instance. 
     At block  406 , the process includes determining a difference between the low-resolution image or the higher-resolution image and a previously captured image of the predetermined area. For example, subsequent captured images may be compared for one or more differences, where the difference(s) may indicate that one or more objects within the predetermined area have moved or are moving. In various implementations, the comparison of the images, and detection of differences (or lack of differences) can trigger a switch in operating modes (standby mode to active mode or active mode to standby mode). 
     At block  408 , the process includes operating the three-dimensional imager in the first operating mode when the difference indicates no object movement within the predetermined area within a preset time duration. For example, the three-dimensional imager may be set to a standby mode when no gesture (i.e., object movement) is detected within the predetermined area, to conserve power. 
     At block  410 , the process includes operating the three-dimensional imager in the second operating mode when the difference indicates an object movement within the predetermined area. For example, the three-dimensional imager may be set to an active mode when a gesture (i.e., object movement) is detected within the predetermined area, for improved performance. 
     In an implementation, the process includes adjusting one or more parameters of the EM radiation and/or the image sensor based on the operating mode (e.g., based on whether movement of an object is detected within the predetermined area). In various implementations, the one or more parameters of the EM radiation may include: activation, illumination time or duty cycle, and modulation of the electromagnetic radiation. For example, in an implementation, the process includes deactivating an illumination of the predetermined area when no object movement is detected within the predetermined area within the preset time duration and activating an illumination of the predetermined area when an object movement is detected within the predetermined area. 
     In various implementations, the one or more parameters of the image sensor may include: resolution and/or dimension, color, pixel modulation, binning of pixels, fractional current readout, reading from a single side or section of a pixel, and frame rate. For example, in an implementation, the process includes refraining from modulating one or more photosensitive pixels of the three-dimensional imager and/or refraining from modulating an illumination of the predetermined area while capturing the low-resolution image, while in the first operating mode. In another implementation, the process includes using a plurality of photosensitive pixels of the three-dimensional imager to capture the higher-resolution, three-dimensional image while in the second operating mode. In a further implementation, the process includes detecting a gesture within the predetermined area while operating in the second operating mode. 
     In further implementations, the process may include reading a fraction of a current generated by one or more photosensitive pixels of the three-dimensional imager while in the first operating mode and/or using a fraction of the plurality of photosensitive pixels of the three-dimensional imager to capture the low-resolution image while in the first operating mode. 
     Another example includes using a first frame rate for capturing an image while in the second operating mode and using a second, lower frame rate for capturing an image while in the first operating mode. In another implementation, the process includes binning photosensitive pixels of the three-dimensional imager while capturing an image in the first operating mode, the binning including combining a group of adjacent pixels and processing the group as single composite pixel. 
     In an implementation, the process further includes time-of-flight techniques such as measuring a time from emitting the EM radiation to receiving the reflection of the EM radiation and calculating a distance of an object based on the measured time. In various implementations, the process includes outputting gesture information to a computing device for input control, or the like. Additionally, the process may include outputting imaging information, such as a distance, a three-dimensional image of the detected object, tracking coordinates of the object, and so forth, to a display device, to another system arranged to process the information, or the like. 
     In alternate implementations, other techniques may be included in the process  400  in various combinations, and remain within the scope of the disclosure. 
     CONCLUSION 
     Although the implementations of the disclosure have been described in language specific to structural features and/or methodological acts, it is to be understood that the implementations are not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as representative forms of implementing example devices and techniques.