Source: http://www.patentsencyclopedia.com/app/20150085133
Timestamp: 2019-04-19 12:47:18+00:00

Document:
Wearable systems with thermal imaging capabilities may be provided for detecting the presence and location of persons or animals in an environment surrounding the system in accordance with an embodiment. A wearable system may include a wearable structure such as a helmet with a plurality of imaging modules mounted to the wearable structure. An imaging module may include one or more imaging components such as infrared imaging modules and visible light cameras. Thermal images captured using the infrared imaging modules may be used to detect the presence of a person in the thermal images. The wearable imaging system may include one or more alert components that alert the wearer when a person is detected in the thermal images. The alert components may be used to generate a location-specific alert that alerts the wearer to the location of the detected person. A wearable imaging system may be a multidirectional threat monitoring helmet.
1. An apparatus, comprising: a wearable structure; a plurality of infrared imaging modules mounted on the wearable structure, wherein each of the infrared imaging modules is configured to capture a thermal image of a scene; and a processor in communication with the plurality of infrared imaging modules, wherein the processor is configured to: detect an object in the scene using the thermal image, and generate an alert for a wearer of the wearable structure when the object is detected.
2. The apparatus of claim 1, further comprising: at least one alert component mounted on the wearable structure, wherein the processor is configured to generate the alert using the at least one alert component.
3. The apparatus of claim 2, wherein the at least one alert component comprises a haptic component.
4. The apparatus of claim 2, wherein the at least one alert component comprises an audio component.
5. The apparatus of claim 2, wherein the at least one alert component comprises a heat-generating component.
6. The apparatus of claim 2, wherein the at least one alert component comprises a plurality of alert components, and wherein the processor is further configured to correct the thermal image according to a non-uniformity correction process using an intentionally blurred thermal image.
7. The apparatus of claim 6, wherein the plurality of alert components comprises an alert component associated with each of the plurality of infrared imaging modules.
8. The apparatus of claim 6 wherein the alert for the wearer comprises a location-specific alert associated with a location of the detected object.
9. The apparatus of claim 8, wherein: the processor is configured to: generate the location-specific alert by operating a selected one of the plurality of alert components.
10. The apparatus of claim 1, wherein the wearable structure comprises a head piece for the wearer.
11. The apparatus of claim 1, wherein the plurality of infrared imaging modules comprise a filter selected from the group consisting of a short-wave infrared filter, a mid-wave infrared filter, a long-wave infrared filter, and a narrow-band filter.
12. The apparatus of claim 1, further comprising at least one non-thermal imaging module mounted on the wearable structure, and wherein the processor is configured to generate an image comprising high-spatial frequency content from an image generated using the at least one non-thermal imaging module fused with the thermal image.
13. A method, comprising: capturing, at a focal plane array (FPA) of an infrared imaging module that is mounted on a wearable structure, a thermal image of a scene within a field of view (FOV) of the infrared imaging module; detecting an object in the thermal image; and generating an alert for a wearer of the wearable structure based on the detected object.
14. The method of claim 13, further comprising: determining a location of the detected object.
15. The method of claim 14, wherein the generating the alert for the wearer of the wearable structure based on the detected object comprises generating a location-specific alert based on the determined location of the detected object.
16. The method of claim 15, wherein the generating the location-specific alert comprises operating an alert component associated with the infrared imaging module.
17. The method of claim 15, wherein the infrared imaging module has a position on the wearable structure and wherein the generating the location-specific alert comprises generating a vibration at the position of the infrared imaging module.
18. The method of claim 13, further comprising: displaying an image of the detected object to the wearer.
19. The method of claim 13, further comprising: communicating detected object information associated with the detected object to an external device.
20. A multidirectional threat monitoring helmet comprising: a protective head covering structure; a plurality of infrared imaging modules mounted around a circumference of the protective head covering structure, each having a field of view that includes a portion of a scene; a plurality of alert components mounted around the circumference of the protective head covering structure; and a processor coupled to the plurality of infrared imaging modules and the plurality of alert components and configured to detect potential threats using the plurality of infrared imaging modules and generate alerts associated with the potential threats using the plurality of alert components.
 This application claims the benefit of U.S. Provisional Patent Application No. 61/886,543 filed Oct. 3, 2013 and entitled "WEARABLE IMAGING DEVICES, SYSTEMS, AND METHODS" which is hereby incorporated by reference in its entirety.
 This application is a continuation-in-part of U.S. patent application Ser. No. 13/940,232 filed Jul. 11, 2013 and entitled "INFANT MONITORING SYSTEMS AND METHODS USING THERMAL IMAGING" which is hereby incorporated by reference in its entirety.
 U.S. patent application Ser. No. 13/940,232 claims the benefit of U.S. Provisional Patent Application No. 61/670,824 filed Jul. 12, 2012 and entitled "INFANT MONITORING SYSTEMS AND METHODS USING THERMAL IMAGING" which is hereby incorporated by reference in its entirety.
 This application is a continuation-in-part of U.S. patent application Ser. No. 14/137,573 filed Dec. 20, 2013 and entitled "IMAGER WITH ARRAY OF MULTIPLE INFRARED IMAGING MODULES" which is hereby incorporated by reference in its entirety.
 U.S. patent application Ser. No. 14/137,573 claims the benefit of U.S. Provisional Patent Application No. 61/745,193 filed Dec. 21, 2012 and entitled "IMAGER WITH ARRAY OF MULTIPLE INFRARED IMAGING MODULES" which is hereby incorporated by reference in its entirety.
 U.S. patent application Ser. No. 14/137,573 is a continuation-in-part of U.S. patent application Ser. No. 13/043,123 filed Mar. 8, 2011 and entitled "IMAGER WITH MULTIPLE SENSOR ARRAYS" which is hereby incorporated by reference in its entirety.
 U.S. patent application Ser. No. 13/043,123 claims the benefit of U.S. Provisional Patent Application No. 61/312,146 filed Mar. 9, 2010 and entitled "MULTI SPECTRAL MINIATURE SENSOR" which is hereby incorporated by reference in its entirety.
 This application is a continuation-in-part of U.S. patent application Ser. No. 13/437,645 filed Apr. 2, 2012 and entitled "INFRARED RESOLUTION AND CONTRAST ENHANCEMENT WITH FUSION" which is hereby incorporated by reference in its entirety.
 This application is a continuation-in-part of U.S. patent application Ser. No. 14/138,058 filed Dec. 21, 2013 and entitled "COMPACT MULTI-SPECTRUM IMAGING WITH FUSION" which is hereby incorporated by reference in its entirety.
 U.S. patent application Ser. No. 14/138,058 claims the benefit of U.S. Provisional Patent Application No. 61/748,018 filed Dec. 31, 2012 and entitled "COMPACT MULTI-SPECTRUM IMAGING WITH FUSION" which is hereby incorporated by reference in its entirety.
 This application is a continuation-in-part of U.S. patent application Ser. No. 14/299,987 filed Jun. 9, 2014 and entitled "INFRARED CAMERA SYSTEMS AND METHODS FOR DUAL SENSOR APPLICATIONS" which is hereby incorporated by reference in its entirety.
 U.S. patent application Ser. No. 14/299,987 is a continuation of U.S. patent application Ser. No. 12/477,828 filed Jun. 3, 2009 and entitled "INFRARED CAMERA SYSTEMS AND METHODS FOR DUAL SENSOR APPLICATIONS" which is hereby incorporated by reference in its entirety.
 This application is a continuation-in-part of U.S. patent application Ser. No. 14/138,040 filed Dec. 21, 2013 and entitled "TIME SPACED INFRARED IMAGE ENHANCEMENT" which is hereby incorporated by reference in its entirety.
 U.S. patent application Ser. No. 14/138,040 claims the benefit of U.S. Provisional Patent Application No. 61/792,582 filed Mar. 15, 2013 and entitled "TIME SPACED INFRARED IMAGE ENHANCEMENT" which is hereby incorporated by reference in its entirety.
 U.S. patent application Ser. No. 14/138,040 also claims the benefit of U.S. Provisional Patent Application No. 61/746,069 filed Dec. 26, 2012 and entitled "TIME SPACED INFRARED IMAGE ENHANCEMENT" which is hereby incorporated by reference in its entirety.
 This application is a continuation-in-part of U.S. patent application Ser. No. 14/138,052 filed Dec. 21, 2013 and entitled "INFRARED IMAGING ENHANCEMENT WITH FUSION" which is hereby incorporated by reference in its entirety.
 U.S. patent application Ser. No. 14/138,052 claims the benefit of U.S. Provisional Patent Application No. 61/793,952 filed Mar. 15, 2013 and entitled "INFRARED IMAGING ENHANCEMENT WITH FUSION" which is hereby incorporated by reference in its entirety.
 U.S. patent application Ser. No. 14/138,052 also claims the benefit of U.S. Provisional Patent Application No. 61/746,074 filed Dec. 26, 2012 and entitled "INFRARED IMAGING ENHANCEMENT WITH FUSION" which is hereby incorporated by reference in its entirety.
 One or more embodiments of the invention relate generally to thermal imaging devices and more particularly, for example, to wearable thermal imaging devices.
 Thermal imaging systems are often used to detect objects in various situations. As examples, law enforcement personnel, defense personnel, security systems, and game hunters sometimes use thermal imaging systems to detect the presence of humans or animals in the surrounding environment of the system.
 However, in conventional systems, a user of a thermal imaging system often must already know the location of the object to be detected, the object to be detected must move in front of a fixed imaging system, or the system must be scanned over an area in order to locate the object. Moreover, these systems are typically either fixed systems that monitor a constant location or handheld systems that require the hands of a user to hold and operate the system.
 Fixed systems can be limited in their ability to detect the presence of objects around a mobile user. Handheld systems can be impractical in situations in which the operator of the system needs free hands for other activities and/or needs constant monitoring of a wide range of angles around the user.
 It would therefore be desirable to provide improved thermal imaging systems.
 Various embodiments are disclosed for wearable imaging systems. A wearable imaging system may be a wearable thermal imaging system and/or a wearable imaging device such as a wearable multisensor array having multiple infrared imaging modules, each with a field of view that includes a portion of a scene. The infrared imaging modules may be mounted on a wearable structure such as a helmet structure. The wearable structure may be formed from rigid materials that protect the wearer from impacts. The wearable structure may be partially or completely covered with a patterned material such as a painted pattern or a patterned fabric.
 The wearable imaging device may include a housing structure that wraps around a portion of the wearable structure. The housing structure may be a detachable structure that can be removed from the wearable structure or can be integrally formed with the housing structure.
 The wearable imaging device may include one or more alert components. Each alert component may be associated with one or more of the infrared imaging modules. For example, each infrared imaging module may include an alert component mounted on the wearable structure next to that infrared imaging module. Alert components may be haptic components such as piezoelectric components, audio components such as speakers, light-emitting components such as light emitting diodes or a display, heat-generating components such as a heating element, or other suitable components for generating alerts for the wearer.
 Thermal images captured using the infrared imaging modules may be processed to detect objects such as a human or an animal. The multisensor array may include a processor that processes the thermal images and detects the objects. When an object is detected, the processor may operate one of the alert components to alert the wearer that an object has been detected. The processor may operate alert components located near the infrared imaging module that captured the image of the object. In this way, the alert component can be used to alert the wearer to both the presence of the object and the location of the object.
 In one embodiment, the wearable imaging device may be implemented as a multidirectional threat monitoring helmet that may be worn by military personnel, law enforcement personnel, hunters or others who desire to be alerted to the presence and location of a living being in their vicinity. For example, a soldier on patrol at night may wish to be alerted to the presence and location of an enemy combatant approaching from a particular direction. A multidirectional threat monitoring helmet may be used to thermally detect the enemy combatant using one or more infrared imaging modules on the helmet and to alert the wearer of the helmet to the presence and location of the enemy combatant.
 FIG. 14 illustrates a block diagram of a host system having an infrared imaging module and a visible light camera in accordance with an embodiment of the disclosure.
 FIG. 15 illustrates an example thermal image that may be captured using an infrared imaging module and analyzed by a processor in accordance with an embodiment of the disclosure.
 FIG. 16 illustrates a process for combining thermal images and visible light images in accordance with an embodiment of the disclosure.
 FIG. 17 illustrates a block diagram of a host system that is implemented as a wearable imaging device with infrared imaging modules and alert components in accordance with an embodiment of the disclosure.
 FIG. 18 illustrates a wearable imaging device that is implemented as a multidirectional threat monitoring helmet in accordance with an embodiment of the disclosure.
 FIG. 19 illustrates a top view of the multidirectional threat monitoring helmet of FIG. 18 showing how multiple imaging modules may be used to monitor portions of the surrounding environment in multiple directions in accordance with an embodiment of the disclosure.
 FIG. 20 illustrates a wearer of a multidirectional threat monitoring helmet wearing the multidirectional threat monitoring helmet along with other systems in accordance with an embodiment of the disclosure.
 FIG. 21 illustrates a block diagram of a threat monitoring system that includes wearable imaging devices in accordance with an embodiment of the disclosure.
 FIG. 22 illustrates a threat monitoring system and shows how one or more multidirectional threat monitoring helmets may communicate with each other and with a base station in accordance with an embodiment of the disclosure.
 FIG. 23 illustrates detection of a moving object with multiple infrared imaging modules on a multidirectional threat monitoring helmet in accordance with an embodiment of the disclosure.
 FIG. 24 illustrates a graph showing how an alert component may provide alerts of an intensity that is based on the distance to a detected object in accordance with an embodiment of the disclosure.
 FIG. 25 illustrates information that may be displayed on a display of a wearable imaging device showing images of detected objects at various locations in accordance with an embodiment of the disclosure.
 FIG. 26 illustrates a process for monitoring an environment using a wearable imaging device in accordance with an embodiment of the disclosure.
 FIG. 27 illustrates a process for monitoring a moving object using a wearable imaging device in accordance with an embodiment of the disclosure.
 In one embodiment, infrared imaging module 100 may be configured to be implemented in a small portable host device 102, such as a mobile telephone, a tablet computing device, a laptop computing device, a personal digital assistant, a visible light camera, a music player, a wearable imaging device, or any other appropriate mobile device. In this regard, infrared imaging module 100 may be used to provide infrared imaging features to host device 102. For example, infrared imaging module 100 may be configured to capture, process, and/or otherwise manage infrared images and provide such infrared images to host device 102 for use in any desired fashion (e.g., for further processing, to store in memory, to display, to use by various applications running on host device 102, to export to other devices, or other uses).
 Infrared sensor assembly 128 may capture images (e.g., image frames) and provide such images from its ROW at various rates. Processing module 160 may be used to perform appropriate processing of captured infrared images and may be implemented in accordance with any appropriate architecture. In one embodiment, processing module 160 may be implemented as an ASIC. In this regard, such an ASIC may be configured to perform image processing with high performance and/or high efficiency. In another embodiment, processing module 160 may be implemented with a general purpose central processing unit (CPU) which may be configured to execute appropriate software instructions to perform image processing, coordinate and perform image processing with various image processing blocks, coordinate interfacing between processing module 160 and host device 102, and/or other operations. In yet another embodiment, processing module 160 may be implemented with a field programmable gate array (FPGA). Processing module 160 may be implemented with other types of processing and/or logic circuits in other embodiments as would be understood by one skilled in the art.
 In the NUC process, blurred image frames may be used to determine NUC terms which may be applied to captured image frames to correct for FPN. As discussed, in one embodiment, the blurred image frames may be obtained by accumulating multiple image frames of a moving scene (e.g., captured while the scene and/or thermal imager is in motion). In another embodiment, the blurred image frames may be obtained by defocusing an optical element or other component of the thermal imager.
 In one embodiment, the risk of introducing scene information into the NUC teens can be further reduced by applying some amount of temporal damping to the NUC term determination process. For example, a temporal damping factor λ between 0 and 1 may be chosen such that the new NUC(NUCNEW) stored is a weighted average of the old NUC term (NUCOLD) and the estimated updated NUC term (NUCUPDATE). In one embodiment, this can be expressed as NUCNEW=λNUCOLD+(1-λ)(NUCOLD+NUCUPDATE).
 Also, by correcting for noise using intentionally blurred image frames captured from a real world scene (not a uniform scene provided by a shutter), noise correction may be performed on image frames that have irradiance levels similar to those of the actual scene desired to be imaged. This can improve the accuracy and effectiveness of noise correction ter is determined in accordance with the various described techniques.
 For example, referring to FIG. 13, when LDO 1220 maintains Vload at a low voltage in the manlier described herein, Vbolo will also be maintained at its corresponding low voltage and the relative size of its output signals may be reduced. As a result, noise, self-heating, and/or other phenomena may have a greater effect on the smaller output signals read out from infrared sensors 132, resulting in variations (e.g., errors) in the output signals. If uncorrected, these variations may be exhibited as noise in the image frames. Moreover, although low voltage operation may reduce the overall amount of certain phenomena (e.g., self-heating), the smaller output signals may permit the remaining error sources (e.g., residual self-heating) to have a disproportionate effect on the output signals during low voltage operation.
 Referring now to FIG. 14, a block diagram is shown of another implementation of host system 102 showing how system 102 may include one or more non-thermal imaging modules such as visible light camera module 1406 in addition to one or more infrared imaging modules such as infrared imaging module 100 in accordance with an embodiment of the disclosure. System 102 may be used to monitor a real-world scene such as scene 1430.
 System 102 may include one or more infrared imaging modules 100, one or more visible light cameras 1406, and additional components as described above in connection with FIG. 1 (e.g., processor 195, memory 196, display 197, one or more motion sensors 194, and/or other components 198 such as a control panel, alert components, or communications components). In various embodiments, components of system 102 of FIG. 14 may be implemented in the same or similar manner as corresponding components of host device 102 of FIG. 1. Moreover, components of system 102 may be configured to perform various NUC processes and other processes described herein.
 As shown in FIG. 14, in some embodiments, infrared imaging module 100 may include various optical elements 1403 (e.g., one or more infrared-transmissive lens, one or more infrared-transmissive prisms, one or more infrared-reflective mirrors, or one or more infrared fiber optic elements) that guide infrared radiation from scene 1430 to an FPA of infrared imaging module 100. In some embodiments, optical elements 1403 may be used to suitably define or alter FOV 1404 of infrared imaging module 100. A switchable FOV (e.g., selectable by infrared imaging module 100 and/or processor 195) may optionally be provided, which may be useful when, for example, a selective close-up view of a portion of scene 1430 is desired.
 Optical elements 1403 may also include one or more filters adapted to pass infrared radiation of some wavelengths but substantially block infrared radiation of other wavelengths (e.g., short-wave infrared (SWIR) filters, mid-wave infrared (MWIR) filters, long-wave infrared (LWIR) filters, and narrow-band filters). Such filters may be utilized to tailor infrared imaging module 100 for increased sensitivity to a desired band of infrared wavelengths. For example, in some situations, it may be desirable to detect exhaled breaths of a person or an animal. In this type of situation, a better result may be achieved by utilizing a narrow-band filter that transmits only in the wavelengths matching a specific absorption/emission spectrum of carbon dioxide (CO2) or other constituent gases of an exhaled breath. In some embodiments, filters may be selectable (e.g., provided as a selectable filter wheel). In other embodiments, filters may be fixed as appropriate for a desired application of system 102.
 Visible light camera 1406 may be a small form factor non-thermal imaging module or imaging device, and may be implemented in a similar manner as various embodiments of infrared imaging module 100 disclosed herein, but with one or more sensors responsive to non-thermal radiation (e.g., radiation in the visible, near infrared, short-wave infrared or other non-thermal portion of the electromagnetic spectrum). For example, in some embodiments, visible light camera 1406 may be implemented with a charge-coupled device (CCD) sensor, an electron multiplying CCD (EMCCD) sensor, a complementary metal-oxide-semiconductor (CMOS) sensor, a scientific CMOS (sCMOS) sensor, an intensified charge-coupled device (ICCD), or other sensors.
 As shown in FIG. 14, in some embodiments, visible light camera module 1406 may include various optical elements 1405 (e.g., one or more lenses, one or more color filters, one or more prisms, one or more mirrors, or one or more fiber optic elements) that guide non-thermal radiation from scene 1430 to visible light camera module 1406. In some embodiments, optical elements 1405 may be used to suitably define or alter FOV 1407 of visible light camera module 1406. A switchable FOV (e.g., selectable by visible light camera module 1406 and/or processor 195) may optionally be provided, which may be useful when, for example, a selective close-up view of a portion of scene 1430 is desired. If desired, elements 1403 and 1405 may be operable to alternately switch between an infrared imaging mode and a visible light imaging mode for system 102.
 Optical elements 1405 may also include one or more filters adapted to pass radiation of some wavelengths (colors) but substantially block radiation of other wavelengths (e.g., red color filters, blue color filters, green color filters, near-infrared color filters, short-wave infrared filters, and narrow-band filters). In some embodiments, filters of elements 1405 may be selectable (e.g., provided as a selectable filter wheel). In other embodiments, filters of element 1405 may be fixed as appropriate for a desired application of system 102. Although camera module 1406 is sometimes referred to herein as a visible light camera module as an example, it should be appreciated that camera module 1406 may be any suitable non-thermal camera module as described herein that generates images in response to incoming light having any suitable corresponding range of non-thermal wavelengths (e.g., visible light wavelengths, near infrared wavelengths, short-wave infrared wavelengths or other wavelengths that are relatively shorter than thermal infrared wavelengths).
 In some embodiments, non-thermal images such as visible light images captured by visible light camera 1406 may be received by processor 195, which may be configured to fuse, superimpose, or otherwise combine the visible light images with the thermal images captured by infrared imaging module 100 as further described herein.
 In some embodiments, visible light camera 1406 may be co-located with infrared imaging module 100 in a housing structure and oriented so that FOV 1407 of visible light camera 1406 at least partially overlaps FOV 1404 of infrared imaging module 100. In one example, infrared imaging module 100 and visible light camera 1406 may be implemented as a dual sensor module sharing a common substrate according to various techniques described in U.S. Provisional Patent Application No. 61/748,018 previously referenced herein. Such a dual sensor module implementation may include common circuitry and/or common restraint devices for infrared imaging and visible light imaging, thereby potentially reducing an overall size of system 102 as compared to embodiments where infrared imaging module 100 and visible light camera 1406 are implemented as individual modules. Additionally, the dual sensor module implementation may be adapted to reduce a parallax error between images captured by infrared imaging module 100 and visible light camera 1406 by reducing the distance between them.
 Infrared images captured, processed, and/or otherwise managed by infrared imaging module 100 may be radiometrically normalized infrared images (e.g., thermal images). That is, pixels that make up the captured image may contain calibrated thermal data (e.g., temperature data). As discussed above in connection with FIG. 1, infrared imaging module 100 and/or associated components may be calibrated using appropriate techniques so that images captured by infrared imaging module 100 are properly calibrated thermal images. In some embodiments, appropriate calibration processes may be performed periodically by infrared imaging module 100 and/or processor 195 so that infrared imaging module 100, and hence the thermal images captured by it, may maintain proper calibration.
 Radiometric normalization permits infrared imaging module 100 and/or processor 195 to efficiently detect, from thermal images, objects having a specific range of temperature. Infrared imaging module 100 and/or processor 195 may detect such objects efficiently and effectively, because thermal images of objects having a specific temperature may be easily discernible from a background and other objects, and yet less susceptible to lighting conditions or obscuring (e.g., obscured by clothing).
 Also referring to FIG. 15, an example thermal image 1530 (shown as a user-viewable thermal image for ease of understanding, with lighter portions representing higher temperatures) that may be captured by infrared imaging module 100 is shown. As this example thermal image shows, a human such as person 1534 generally exhibits a higher temperature than a background such as background 1532. Furthermore, facial features 1533 such as a mouth and nostrils, glasses 1536, clothed portion 1535, and object 1540 (e.g., an object held in the person's hand) generally exhibit various temperatures that can be differentiated in a thermal image such as thermal image 1530. Thus, various features of a person such as person 1534 that is detected in a thermal image such as image 1530 may be accurately and yet efficiently differentiated and tracked using appropriate detection and tracking operations described herein and elsewhere.
 In some embodiments, if visible light images captured by visible light camera 1406 are available, processor 195 may be configured to track features of a scene such as multiple individual people or even the face and facial features of an individual person based additionally or alternatively on the visible light images. For example, the visible light images may provide more detail and contrast than the thermal images in certain ambient light conditions, and thus may be analyzed using suitable face tracking algorithms in such favorable light conditions. In another example, both the visible light images and the thermal images may be analyzed to complementarily increase detection and tracking accuracy. In another example, the thermal images and the visible light images may be combined or fused as further described herein, and the combined or fused images may be analyzed to track the features of the scene. If processor 195 is configured to detect and track the features of a scene using the visible light images, processor 195 may be further configured to convert pixel coordinates of the tracked features in the visible light images to corresponding pixel coordinates in the thermal images.
 In some embodiments, thermal images from one or more infrared imaging modules such as infrared imaging module 100 and non-thermal images from one or more non-thermal camera modules such as visible light camera module 1406 may be fused or combined to generate images having a higher definition, contrast, and/or detail.
 The fusing or combining operations in accordance with one or more embodiments may be described in further detail with reference to FIG. 16, which is a flowchart of a process 1600 to combine or fuse the thermal images and the non-thermal (e.g., visible light) images. The combined images may include radiometric data and/or other infrared characteristics corresponding to scene 1430, but with significantly more object detail (e.g., contour or edge detail) and/or contrast than typically provided by the thermal or non-thermal images alone. Thus, for example, the combined images generated in these examples may beneficially provide sufficient radiometric data, detail, and contrast to allow easier recognition and/or interpretation of the presence, location, position, or other features of objects such as humans or animals in scene 1430.
 Although the process described herein in connection with FIG. 16 discusses fusing or combining thermal images with visible light images as an example, it should be appreciated that the process may be applied to combining thermal images with any suitable non-thermal images (e.g., visible light images, near infrared images, short-wave infrared images, EMCCD images, ICCD images, or other non-thermal images).
 At block 1602, visible light images and infrared images such as thermal images may be received. For example, visible light images of scene 1430 may be captured by visible light camera 1406 and the captured visible light images may be received by processor 195. Processor 195 may perforin various operations of process 1600 using both thermal images and non-thermal images, for example.
 At block 1604, high spatial frequency content from one or more of the visible light and thermal images may be derived from one or more of the visible light and thermal images received in block 1602. High spatial frequency content derived according to various embodiments may include edge/contour details and/or high contrast pixels extracted from the one or more of the visible light and thermal images, for example.
 In one embodiment, high spatial frequency content may be derived from the received images by performing a high pass filter (e.g., a spatial filter) operation on the images, where the result of the high pass filter operation is the high spatial frequency content. In an alternative embodiment, high spatial frequency content may be derived from the received images by performing a low pass filter operation on the images, and then subtracting the result from the original images to get the remaining content, which is the high spatial frequency content. In another embodiment, high spatial frequency content may be derived from a selection of images through difference imaging, for example, where one image is subtracted from a second image that is perturbed from the first image in some fashion, and the result of the subtraction is the high spatial frequency content. For example, optical elements 1403 of infrared imaging module 100 and/or optical elements 1405 of visible light camera 1406 may be configured to introduce vibration, de-focusing, and/or movement artifacts into a series of images captured by one or both of infrared imaging module 100 and visible light camera 1406. High spatial frequency content may be derived from subtractions of images such as adjacent images in the series.
 In some embodiments, high spatial frequency content may be derived from only the visible light images or the thermal images. In other embodiments, high spatial frequency content may be derived from only a single visible light or thermal image. In further embodiments, high spatial frequency content may be derived from one or more components of the visible light and/or thermal mages, such as a luminance component of visible light images, for example, or a radiometric component of thermal images. Resulting high spatial frequency content may be stored temporarily (e.g., in memory 196) and/or may be further processed according to block 1608.
 At block 1606, one or more thermal images may be de-noised. For example, processor 195 may be configured to de-noise, smooth, or blur one or more thermal images of scene 1430 using a variety of image processing operations. In one embodiment, removing high spatial frequency noise from the thermal images allows the processed thermal images to be combined with high spatial frequency content derived according to block 1604 with significantly less risk of introducing double edges (e.g., edge noise) to objects depicted in combined images of scene 1430.
 In another embodiment, processed thermal images may be derived by actively blurring thermal images of scene 1430. For example, optical elements 1403 may be configured to slightly de-focus one or more thermal images captured by infrared imaging module 100. The resulting intentionally blurred thermal images may be sufficiently de-noised or blurred so as to reduce or eliminate a risk of introducing double edges into combined images of scene 1430, as further described below. In other embodiments, blurring or smoothing image processing operations may be performed by processor 195 on the received thermal images as an alternative or supplement to using optical elements 1403 to actively blur thermal images of scene 1430. Resulting processed thermal images may be stored temporarily (e.g., in memory 196) and/or may be further processed according to block 1608.
 At block 1608, high spatial frequency content may be blended with one or more thermal images. For example, processor 195 may be configured to blend high spatial frequency content derived in block 1604 with one or more thermal images of scene 1430, such as the processed thermal images provided in block 1606.
 In one embodiment, high spatial frequency content may be blended with thermal images by superimposing the high spatial frequency content onto the thermal images, where the high spatial frequency content replaces or overwrites those portions of the thermal images corresponding to where the high spatial frequency content exists. For example, the high spatial frequency content may include edges of objects depicted in images of scene 1430, but may not exist within the interior of such objects. In such embodiments, blended image data may simply include the high spatial frequency content, which may subsequently be encoded into one or more components of combined images, as described in block 1610.
 A blending parameter value may be selected by a user or may be automatically determined by processor 195 according to context or other data, for example, or according to an image enhancement level expected by system 102. In some embodiments, the blending parameter may be adjusted or refined while combined images are being displayed (e.g., by display 197). In some embodiments, a blending parameter may be selected such that blended image data includes only thermal characteristics, or, alternatively, only visible light characteristics. A blending parameter may also be limited in range, for example, so as not to produce blended data that is out-of-bounds with respect to a dynamic range of a particular color space/format or a display.
 At block 1610, the blended data may be encoded into one or more components of the combined images. For example, processor 195 may be configured to encode blended data derived or produced in accordance with block 1608 into combined images that increases, refines, or otherwise enhances the information conveyed by either the visible light or thermal images viewed by themselves. In some embodiments, encoding blended image data into a component of combined images may include additional image processing operations, for example, such as dynamic range adjustment, normalization, gain and offset operations, noise reduction, and color space conversions, for instance.
 In addition, processor 195 may be configured to encode other image data into combined images. For example, if blended image data is encoded into a luminance component of combined images, a chrominance component of either visible light images or thermal images may be encoded into a chrominance component of combined images. Selection of source images may be made through user input, for example, or may be determined automatically based on context or other data. More generally, in some embodiments, a component of combined images that is not encoded with blended data may be encoded with a corresponding component of visible light images or thermal images. By doing so, a radiometric calibration of thermal images and/or a color space calibration of visible light images may be retained in the resulting combined images.
 In some embodiments, at least some part or some functionalities of processor 195 described herein may be implemented as part of infrared imaging modules 100, for example, at processing module 160 described above in connection with FIG. 3. In some embodiments, at least some part or some functionalities of processor 195 may be part of or implemented with other existing processors of an external device such as a mobile phone, a tablet device, a mobile handset, a laptop computer, a desktop computer, an automobile information display system, or any other devices that may be used to present monitoring information from a monitoring system. In other embodiments, processor 195 may interface and communicate with such other external processors and components associated with such processors.
 In one suitable configuration that is sometimes discussed herein as an example, system 102 may be implemented as a wearable device such as wearable imaging device 1700 of FIG. 17. As shown in FIG. 17, wearable imaging device 1700 may include one or more wearable structures such as wearable structure 1701 and one or more infrared imaging modules 100. Wearable imaging device 1700 may, for example, be a wearable multisensor array that includes several infrared imaging modules 100 that each have a field of view (FOV) that covers a portion of a scene such as scene 1430.
 In one embodiment, wearable structure 1701 may be a head piece such as a protective helmet that protects a wearer's head from injury due to a fall, a falling object or a projectile such as a bullet. However, this is merely illustrative. If desired, wearable structure 1701 may be another wearable structure such as a hat, a backpack, an arm band, a leg strap, goggles, glasses, or other suitable clothing piece on which infrared imaging devices can be mounted or integrated.
 As shown in FIG. 17, wearable imaging device 1700 may include one or more visible light cameras 1406, one or more motion sensors 194, one or more batteries such as battery 1704, memory such as memory 196, one or more processors such as processor 195, communications components such as wired or wireless communications components 1706, and one or more wearer alert modules such as alert component 1702.
 Alert component 1702 may include one or more haptic components, audio components, light-emitting components, heat-generating components, displays such as display 197 or other suitable components for providing an alert to a wearer of wearable imaging device 1700 in response to the detection of an object in image data from infrared imaging module(s) 100 and/or visible light camera(s) 1406).
 Haptic components may include mechanical vibrators, piezoelectric components, or other movable components for generating motion in device 1700 to alert the wearer of device 1700. Audio components may include one or more speakers. Light-emitting components may include one or more light-emitting diodes, light bulbs, portions of a display, other light-generating components. Heat-generating components may include resistive heating elements such as ceramic heating elements or other suitable components for generating heat to alert the wearer of device 1700 of a detected object in a thermal and/or visible light image. A display may include a monochrome or color display that uses any suitable display technology (e.g., liquid-crystal, light-emitting-diode, or other display technology).
 Battery 1704 may be a lithium ion battery, a lithium polymer battery, a nickel cadmium battery, a nickel metal hydride battery, or other suitable type of battery technology for a portable wearable imaging device. System 1700 may include one, two, three, or more than three batteries or, if desired, system 1700 may be powered by an external battery or battery pack (e.g., through a wired connection to a battery in a backpack or other portable vessel).
 Memory 196 may include one or more memory devices to store data and information, including thermal images and monitoring information. The one or more memory devices may include various types of memory for thermal image and other information storage including volatile and non-volatile memory devices, such as RAM (Random Access Memory), ROM (Read-Only Memory), EEPROM (Electrically-Erasable Read-Only Memory), flash memory, and/or a disk drive. In one embodiment, thermal images and monitoring information stored in the one or more memory devices may be retrieved later for purposes of reviewing and/or further diagnosing the conditions of the environment monitored by device 1700. In various embodiments, processor 195 may be configured to execute software instructions stored on memory 196 to perform various methods, processes, or operations in the manner described herein.
 Display 197 may be configured to present, indicate, or otherwise convey monitoring information generated by processor 195, infrared imaging modules 100, and/or visible light cameras 1406. In various embodiments, display 197 may be implemented with an electronic display screen, such as a liquid crystal display (LCD), a cathode ray tube (CRT), light-emitting-diode (LED) or various other types of generally known video displays and monitors. Display 197 according to such embodiments may be suitable for presenting user-viewable thermal images converted by processor 195 from thermal images captured by infrared imaging modules 100.
 In some embodiments, existing display screens on external devices such as mobile phones, tablet devices, laptop computers, desktop computers, automobile information display systems, or any other devices that may receive thermal images and/or the monitoring information from wearable imaging device 1700 to present the monitoring information to a user.
 In this regard, communications components 1706 may be configured to handle, manage, or otherwise facilitate wired and/or wireless communication between various components of wearable imaging device 1700 and between wearable imaging device 1700 and an external device. For example, wearable imaging device 1700, may transmit and receive data to and from other wearable imaging devices 1700 or to and from other equipment such as a base station through communications components 1706. In another example, wearable imaging device 1700 may transmit and receive data to and from an external device, which may receive and further process raw/processed thermal images and/or monitoring information for presentation to a user, through communications components 1706 configured to manage wired and/or wireless connections.
 In various embodiments, communications components 1706 may include a wireless communication component (e.g., based on the IEEE 802.11 WiFi standards, the Bluetooth® standard, the ZigBee® standard, or other appropriate short range wireless communication standards), a wireless broadband component (e.g., based on WiMax technologies), mobile cellular component, a wireless satellite component, or other appropriate wireless communication components. Communication module 1706 may also be configured for a proprietary wireless communication protocol and interface based on radio frequency (RF), microwave frequency (MWF), infrared frequency (IRF), and/or other appropriate wireless transmission technologies. Communications components 1706 may include an antenna coupled thereto for wireless communication purposes. Thus, in one example, communications components 1706 may handle, manage, or otherwise facilitate wireless communication by establishing wireless link to other wearable imaging device 1700, to a base station, to a wireless router, hub, or other appropriate wireless networking devices.
 In various embodiments, communications components 1706 may be configured to interface with a wired network via a wired communication component such as an Ethernet interface, a power-line modem, a Digital Subscriber Line (DSL) modem, a Public Switched Telephone Network (PSTN) modem, a cable modem, and/or other appropriate components for wired communication. Proprietary wired communication protocols and interfaces may also be supported by communication module 1706. Communications components 1706 may be configured to communicate over a wired link (e.g., through a network router, switch, hub, or other network devices) for wired communication purposes. For example, a wired link may be implemented with a power-line cable, a coaxial cable, a fiber-optics cable, or other appropriate cables or wires that support corresponding wired network technologies.
 In some embodiments, wearable imaging device 1700 may comprise as many such communication components 1706 as desired for various applications of wearable imaging device 1700 to suit various types of monitoring environments. In other embodiments, communication components 1706 may be integrated into or implemented as part of various other components of wearable imaging device 1700. For example, infrared imaging module 100, processor 195, and display 197 may each comprise a subcomponent that may be configured to perform the operations of communications components 1706, and may communicate via wired and/or wireless connection without separate components 1706.
 Motion sensors 194 may be monitored by and provide information to infrared imaging modules 100 and/or processor 195 for performing various NUC techniques described herein.
 In various embodiments, one or more components of wearable imaging device 1700 may be combined and/or implemented or not, as desired or depending on application requirements. For example, processor 195 may be combined with infrared imaging modules 100, memory 196, and/or communications components 1706. In another example, processor 195 may be combined with infrared imaging modules 100 with only certain operations of processor 195 performed by circuitry (e.g., processor, logic device, microprocessor, microcontroller, etc.) within infrared imaging modules 100.
 If desired, wearable imaging device 1700 may include one or more alert components associated with each infrared imaging module 100. In this way, when an object such as a person is detected in images from one of infrared imaging modules 100, alert components associated with that infrared imaging device (e.g., one or more alert components 1702 that are co-located with that infrared imaging device) can be activated to alert the wearer to both the presence and the location of the detected person.
 Infrared imaging modules 100 of wearable imaging device 1700 may be configured to capture, process, and/or otherwise manage infrared images (e.g., including thermal images) of a scene such as scene 1430 (see FIG. 14). In this regard, infrared imaging modules 100 may be attached, mounted, installed, or otherwise disposed at any suitable location on or within device 1700 that allows at least a portion of the scene to be placed within field of view (FOV) 1404 of each infrared imaging module 100.
 In one embodiment, several infrared imaging modules may be disposed around some or all of a wearable structure such as a helmet as shown in FIG. 18. In the example of FIG. 18, wearable structure 1701 of FIG. 17 is implemented as a protective head covering structure such as protective helmet 1802. A wearable imaging device that has been implemented as multidirectional threat monitoring helmet of the type shown in FIG. 18 may be provided with imaging modules 1804 at various locations on helmet 1802. For example, imaging modules 1804 may be disposed at various locations around a circumference of a wearable structure such as helmet 1802. Each imaging module 1804 may include an infrared imaging module 100, a visible light camera 1406, an infrared imaging module 100 and a visible light camera 1406, more than one infrared imaging module 100, more than one visible light camera 1406 or any other suitable combination of individual imaging components 1810.
 Wearable imaging device 1700 may include imaging components 1810 in a housing such as housing 1812. In some embodiments, housing 1812 may include clamps, clips, suction cups, or other suitable attachment mechanisms to releasably attach housing 1812, and hence imaging components (e.g., infrared imaging modules 100), to a suitable wearable mounting structure such as helmet 1802. In some embodiments, housing 1812 may be fixedly attached to a mounting structure with an appropriate fastener.
 Additional components such as processor 195, communications components 1706, and memory 196 may be located within housing 1812 or within other portions of helmet 1802. Wearable imaging device 1700 may include additional structures such as chin strap 1808 for holding helmet 1802 in place on a wearer's head, and flap structure 1806. Flap structure 1806 may be a structural component and/or a functional component of device 1700. For example, flap structure 1806 may include a display such as a flip-down display that the wearer of device 1700 can move into and out of view for viewing images based on image data captured using imaging components 1810.
 Infrared imaging modules 100 may be attached to a wearable structure such as a helmet as needed in order to place up to 360 degrees of a real-world scene within the FOV of the infrared imaging modules.
 FIG. 19 is a top view of wearable imaging device 1700 showing how multiple imaging modules 1804 (each containing one or more imaging components such as infrared imaging modules 100 and/or visible light cameras 1406) may be disposed around helmet 1802 and pointed in a particular direction 1910. A wearable imaging device configured in this way may allow each imaging module 1804 to view a portion of a complete 360 degree scene around the wearer of device 1700. In this way, device 1700 may be used to monitor potential threats to the wearer of device 1700 in a multidirectional manner.
 As shown in FIG. 19, a wearable imaging device 1700 that is implemented as a multidirectional threat monitoring helmet may include additional structures and components such as components 1902, 1904, and 1918. In various embodiments, components 1902, 1904, and 1918 may each be functional components (e.g., additional infrared or visible light imaging devices, processors, memory, batteries, communications components, motion sensors, alert components, or other functional components) or structural components such as strength reinforcing structures (e.g., woven bulletproof structures, metal or polymer strengthening components, etc.). In one suitable example, components 1902 may be alert components such as alert components 1702 of FIG. 17 that are associated with each imaging module 1804. Alert components may be positioned at various locations around a circumference of helmet 1802 (e.g., at locations corresponding to the positions of infrared imaging modules disposed around the circumference).
 As shown in FIG. 20, in some embodiments, wearable imaging device 1700 may be integrated into a larger wearable system such as system 2000. System 2000 may be an individual tactical defense system for a person such as soldier 2010 that includes wearable imaging device 1700, additional cameras such as camera 2002, weapons such as rifle 2006, display devices such as display 2004, and backpack 2009.
 Backpack 2009 may be used to carry a power supply, additional memory, or other components or devices for operating device 1700 and/or other components of system 2000.
 Display 2004 may be a portion of wearable imaging device 1700 (e.g., a flip-down, or drop-down display that displays images captured using infrared imaging modules 100 and/or visible light cameras 1406 mounted in housing 1812 on helmet 1802) or may be a separate display component. Display 2004 may be used to display images from other portions of system 2000 (e.g., additional camera 2002 or weapon 2006).
 As shown in FIG. 20, helmet 1802 may include a patterned cover material such as such as patterned material 2012 that matches patterned material 2012 on other portions of a wearer's clothing to reduce the visibility of wearer 2010 to others. Patterned material 2012 may be a patterned fabric, a patterned coat of paint, or other patterned material. Patterned material 2012 may have a camouflage pattern suitable for an environment in which wearer 2010 is located.
 In one embodiment, wearable imaging device 1700 (e.g., processor 195) may be configured to generate image data such as thermal images from multiple imaging modules 1804 and to detect from the thermal images a contiguous region of pixels (also referred to as a "blob" or "warm blob") having a temperature approximately in the range of a person, for example, between approximately 75° F. (e.g., clothed part of a body) and approximately 110° F. (e.g., exposed part of a body such as a face and hands). Such a "warm blob" may indicate a presence of a person in the vicinity of device 1700, and may be analyzed further as described herein to ascertain the presence of the person, track the motion of the person, determine the location of the person, and/or determine various other attributes associated with the detected person.
 Processor 195 may be configured to receive thermal image data captured by infrared imaging modules 100. Processor 195 may be configured to perform, on the received thermal images of a scene, various thermal image processing and analysis operations as further described herein, for example, to detect and track a person or an animal, and determine various attributes associated with the person or animal. Processor 195 may be configured to collect, compile, analyze, or otherwise process the outcome of the thermal image processing and analysis operations to generate monitoring information such as threat detection information.
 In one example, wearable imaging device 1700 may be configured to determine the presence and location of a human (or an animal), and generate an alert upon detection of the human (or animal). In this regard, wearable imaging device 1700 may be configured to detect and track the location of the person or animal and, if desired, detect and track a face and facial features or other features of a person in the thermal images according to one or more embodiments of the disclosure. Wearable imaging device 1700 may be configured to alert the wearer of device 1700 to the location of the detected person (or animal) by activating an alert component located near the imaging module that generated the images in which the person was detected. For example, if a person is located behind the wearer, a vibration, a sound, and/or heat (as examples) at the rear of the helmet may be generated to form a location-specific alert for the wearer of the detected person behind them.
 In other embodiments, if visible light images captured by visible light cameras 1406 in imaging modules 1804 are available, wearable imaging device 1700 may be configured to track features of a scene such as multiple individual people or even the face and facial features of an individual person based additionally or alternatively on the visible light images. For example, the visible light images may provide more detail and contrast than the thermal images in certain ambient light conditions, and thus may be analyzed using suitable face tracking algorithms in such favorable light conditions. In another example, both the visible light images and the thermal images may be analyzed to complementarily increase detection and tracking accuracy. In another example, the thermal images and the visible light images may be combined or fused as further described herein, and the combined or fused images may be analyzed to track the features of the scene. If wearable imaging device 1700 is configured to detect and track the features of a scene using the visible light images, processor 195 may be further configured to convert pixel coordinates of the tracked features in the visible light images to corresponding pixel coordinates in the thermal images.
 In one embodiment, wearable imaging device 1700 may be configured to detect a presence of exhaled breaths of a person or animal. Exhaled breaths may appear in the thermal images for a short period after each exhalation, and may be detectable as a distinct plume of gas rich in CO2 and having a temperature slightly lower than the body temperature. Thus, by analyzing images to detect a group of pixels having radiometric properties characteristic of such gases, exhaled breaths may be detected. Moreover, as discussed above in connection with optical elements 1403 of infrared imaging module 100, narrow-band filters may be utilized in some embodiments of modules 100 in wearable imaging device 1700, so that infrared radiation absorbed and emitted by CO2 may be shown more clearly and in higher contrast to infrared radiation from other substances for an improved detection of exhaled breaths. Wearable imaging device 1700 may be configured to generate an alert such as a location-specific alert when, for example, an exhaled breath is detected.
 In another embodiment, wearable imaging device 1700 may be configured to detect breathing by analyzing infrared images captured using one or more infrared imaging modules 100 to detect periodic variations in the temperature and/or shape of a detected oronasal region of a detected person or animal. For example, wearable imaging device 1700 may be configured to detect periodic alteration of slightly higher and lower temperatures in the nostrils and/or periodic movement of the oronasal region, which may be indicative of periodic inhalation and exhalation cycles. It is also contemplated that wearable imaging device 1700 may be configured to detect breathing by performing other suitable analysis and/or processing operations, for example, for detecting various periodic variations indicative of breathing. In various embodiments, processor 195 may be configured to detect breathing by performing any combination of breathing detection operations described herein.
 In another example, monitoring information that may be generated by wearable imaging device 1700 includes an approximate body temperature of person or animal and/or an alert to warn of detected objects having a temperature similar to a typical human or animal. As described above, wearable imaging device 1700 may be configured to locate and track a person or animal in the thermal images by analyzing the thermal images, visible light images, and/or combined thermal-visible light images from imaging modules 1804. In one embodiment, processor 195 may be configured to determine an approximate body temperature by aggregating, averaging, and/or otherwise analyzing the radiometric data (e.g., temperature data) associated with thermal image pixels that correspond to the person or animal.
 In other embodiments wearable imaging device 1700 may be configured to calculate an approximate body temperature by performing other appropriate processing and analysis operations on the thermal images and the radiometric data contained therein. In various embodiments, processor 195 may be configured to generate an alert if an object having the approximate body temperature of a human, as determined from the thermal images is detected.
 In yet another example of generating monitoring information, wearable imaging device 1700 may be configured to analyze the thermal images to determine the approximate posture of a detected person (e.g., whether the person is standing, crouching, prone, sitting, walking, running, etc.) or the approximate orientation of the detected person (e.g., facing toward or facing away from an infrared imaging module 100). As described above, the location of body, face, and facial features of a detected person or animal may be tracked in the thermal images. In one embodiment, wearable imaging device 1700 may be configured to determine the approximate posture by analyzing the location and/or orientation of the face relative to the body.
 In another embodiment, the profile and/or the aspect ratio of the person in the thermal images may be analyzed to determine the posture. In various embodiments, wearable imaging device 1700 may be configured to determine the posture of the person by performing any combination of posture detection operations described herein and other appropriate thermal image analysis operations for posture detection. In various embodiments, wearable imaging device 1700 may be configured to receive a selection of an alert-triggering posture from a user, and generate an alert if the approximate posture of the person is detected as matching the selected posture. Thus, for example, a user may choose to be notified or warned if the person is in a crouched position facing toward the user, so that the user may take precautionary measures to defend against a potential threat.
 FIG. 21 is a block diagram showing how multiple wearable imaging devices may be communicatively coupled to each other and to other components of a larger system. As shown in FIG. 21, system 2100 may include one or more wearable imaging device 1700 and a base station 2102. Each wearable imaging device 1700 may be communicatively coupled to each other wearable imaging device over a communications path 2110 (e.g., a wireless radio-frequency communications path). Each wearable imaging device 1700 may be communicatively coupled to base station 2102 over communications paths 2108 (e.g., a wireless radio-frequency communications path). In some embodiments, one of wearable imaging devices 1700 may serve as a base station (e.g., a wearable imaging device worn by a commander of a unit of soldiers wearing devices 1700). However, this is merely illustrative. In some embodiments, wearable imaging devices 1700 may communicate with base station 2102 through an antenna such as antenna 2104 and/or through a network such as network 2106 (e.g., a closed proprietary network or a global network such as the Internet).
 For example, wearable imaging devices 1700 may transmit signals to antenna 2104 over paths 2112 (e.g., wired or wireless communications paths) and antenna 2104 may transmit some or all of the received signals to base station 2102 over path 2134 (e.g., a wired or wireless communications path). As another example, wearable imaging devices 1700 may transmit signals to antenna 2104 over paths 2112, antenna 2104 may transmit some or all of the received signals network 2106 over path 2135 (e.g., a wired or wireless communications path) and base station 2102 may receive information associated with the signals over path 2136 (e.g., a wired or wireless communications path).
 As shown in FIG. 21, base station 2102 may include computing equipment 2114. Computing equipment 2114 may be located in a common geographical location with wearable imaging devices 1700 or may be located remote from wearable imaging devices 1700. For example, base station 2102 may be a remote command center that communicates with soldiers in various geographical locations or base station 2102 may be a field command center from which the soldiers are locally deployed.
 Computing equipment 2114 may include various computing modules suitable for communicating with devices 1700 and for processing and storing images and/or other monitoring information received from devices 1700. Computing equipment 2114 may include one or more displays 2116, storage such as memory 2118, processing equipment such as processor 2120, communications components such as communications module 2122, control components such as control panel 2128, input components such as input components 2130 and/or output components such as output components 2132. Communications module 2122 may include one or more antennas 2124 and additional communications circuitry 2126 (e.g., radio-frequency front end circuitry, signal generation circuitry, modulation circuitry, etc.). Input components 2130 may include a microphone, a keyboard, a touchscreen, a mouse, and/or other components suitable for receiving user input. Output components may include one or more speakers, headphones, or other output components.
 As shown in FIG. 22, multiple wearable imaging devices 1700 may be used to communicate with each other, with base station 2102 and, if desired, an additional remote command center such as command center 2200. Command center 2200 may communicate with base station 2102 and/or devices 1700 through antenna 2104 and network 2106. For example, command center 2200 may be located on a ship, underground, in a different country, on a different continent, or may be otherwise remotely located from wearable imaging devices 1700. In some embodiments, when one of devices 1700 detects an object such as a potential human threat, that device may alert the wearer of the device and may also transmit detection and location information associated with the detected object to other devices 1700 which may, in turn, alert the wearers of those devices to the detection and location of the object.
 FIG. 23 is a diagram of wearable imaging device 1700 showing how a selected one of imaging modules 1804 may be used to detect an object in a given location. As shown in FIG. 23, device 1700 has several imaging modules such as modules 1804-1, 1804-2, and 1804-3 disposed around helmet 1802. As shown, imaging module 1804-1 has a field of view 2308-1, imaging module 1804-2 has a field of view 2308-2, and imaging module 1804-3 has a field of view 2308-3. When an object such as object 2304 (e.g., a human, an animal, or other detectable object) enters the field of view of a particular imaging module, device 1700 may use images captured using that imaging module to detect the object. In the example of FIG. 23, object 23 is located in the field of view of both imaging modules 1804-2 and 1804-3.
 In the example of FIG. 23, an alert component is also associated with each imaging module. Alert component 2302-1 is located next to imaging module 1804-1, alert component 2302-2 is located next to imaging module 1804-2, and alert component 2302-3 is located next to imaging module 1804-3. In this way, when object 2304 is detected in the fields of view of modules 1804-2 and 1804-3, alert components 2302-2 and 2302-3 can be operated to alert the wearer of device 1700 to the presence and location of object 2304.
 If desired, alert components 2302-2 and 2302-3 can be operated in conjunction to generate an alert for the wearer that seems to originate between modules 2302-2 and 2302-3 when an object is detected by modules 2302-2 and 2302-3. In this way, device 1700 may be able to alert the wearer to the location of an object to higher resolution than the number of alert components. Alert components 2302-1, 2302-2, and 2302-3 may each be an implementation of one of alert components 1702 of FIG. 17. The one-to-one correspondence of alert components to imaging modules in FIG. 23 is merely illustrative. If desired, device 1700 may include more alert components than imaging modules, fewer alert components than imaging modules, or one or more continuous alert components that can be partially (locally) activated.
 FIG. 23 also shows how the fields of view of imaging modules 1804 may at least partially overlap so that if an object such as object 2304 moves out of the FOV of one imaging module (e.g., to a position 2306 as indicated by arrow 2305), another imaging module may be used to detect and track the object at its new location.
 In some embodiments, images captured using imaging modules 1804 (e.g., using infrared imaging modules 100) may also be used to determine approximate distances to detected objects such as object 2304. If desired, alert components 1702 may be used to alert the wearer of device 1700 to the distance of the object in addition to the angular position of the object. For example, alert components 1702 may be operated with an intensity that depends on the distance to the object as shown in FIG. 24.
 In yet another example, alerts that can be generated for a wearer of a wearable imaging device 1700 such as a multidirectional threat monitoring helmet include user-viewable images (e.g., thermograms) of a scene captured by imaging modules 1804. FIG. 25 shows a portion of display 197 that is displaying user-viewable image 2500. Wearable imaging device 1700 (e.g., processor 195) may be configured to convert thermal images using appropriate methods and algorithms. In one embodiment, the radiometric data (e.g., temperature data) contained in the pixels of the thermal images may be converted into gray-scaled or color-scaled pixels to construct an image such as image 2500 that can be viewed by a person. User-viewable thermal image 2500 may optionally include a legend or scale such as scale 2505 that indicates the approximate temperature of corresponding pixel color and/or intensity and an angular scale such as scale 2506 that indicates the location of detected objects such as person 2502 and/or animal 2504. Such user-viewable images may be viewed by a user (e.g., a soldier, a law-enforcement officer, or a hunter) to visually determine the location of potential threats even in dark environments (e.g., at night).
 If visible light images of the scene are available (e.g., captured by visible light camera 1406), processor 195 may be configured to superimpose, fuse, blend, or otherwise combine the thermal images and the visible light images to generate user-viewable image 2500 having a higher definition and/or contrast. For example, processor 195 may be configured to generate images 2500 that are combined images including radiometric data and/or other infrared characteristics corresponding to scene but with significantly more object detail (e.g., contour and/or edge detail) and/or contrast than typically provided by the thermal or visible light images alone, as further described herein. In another example, images such as image 2500 may be combined images that include radiometric data and visible light characteristics (e.g., a visible spectrum color) corresponding to one or more objects (e.g., a person) in scene, as described for appropriate embodiments disclosed in various patent applications referenced herein such as, for example, U.S. Patent Application Nos. 61/473,207, 61/746,069, 61/746,074, 61/792,582, 61/793,952, Ser. Nos. 12/766,739, 13/105,765, or 13/437,645, or International Patent Application No. PCT/EP2011/056432, or others as appropriate. Combined images generated in these examples may provide sufficient radiometric data, edge detail, and contrast to allow easier recognition and/or interpretation of the presence, location, and position of a detected person 2502 or animal 2504.
 As shown in FIG. 25, in some embodiments, wearable imaging device 1700 may allow a user to define a virtual boundary 2508. A user may define virtual boundary 2508 through, for example, an interaction with a control panel, a GUI presented on display 197, or other input component. Virtual boundary 2508 may be defined by a user to delineate an area where it may be unsafe or otherwise undesirable for an approaching person to enter. For example, alerts may be generated by device 1700 if a person enters the area inside virtual boundary 2508. In other embodiments, the detection may be performed using one or more image analysis operations (e.g., video analytics), which may include scene reconstruction operations, object tracking operations, and/or virtual tripwire detection operations. The example of a virtual boundary is merely illustrative. If desired, device 1700 may generate an alert when a person (or animal or other object) is detected at any location.
 Referring now to FIG. 26, a flowchart is illustrated of a process 2600 for detecting objects and alerting a wearer using a wearable imaging device such as wearable imaging device 1700.
 At block 2602, thermal images (e.g., images containing pixels with radiometric data) of a scene may be captured by one or more infrared imaging modules (e.g., infrared imaging modules 100 disposed around a wearable structure such as helmet 1802). The captured thermal images may be radiometrically calibrated thermal images as described above in connection with infrared imaging module 100. If desired, visible light images may also be captured at block 2602 using visible light cameras 1406 on a wearable structure such as helmet 1802.
 At block 2604, processing operations may be performed on the captured thermal images. Processing operations may include NUC corrections, other noise corrections, calibration operations, smoothing operations, filtering operations, edge detection operations, perspective calibration operations or other image processing operations. Additional processing operations may also be performed on visible light images optionally captured at block 2602. Is some embodiments, image processing operations performed at block 2604 may include combining or fusing thermal images and visible light images as described above in connection with FIGS. 14 and 16 (as examples). NUC correction processes may be performed on the captured the thermal images to remove noise therein, for example, by using various NUC techniques disclosed herein.
 At block 2606, one or more objects such as a person, an animal, a vehicle, or other moving or stationary objects may be detected using the processed thermal images. Detecting the objects may include identifying image pixels in the thermal images that correspond to the temperature of a person or an animal, identifying image pixels that correspond to exhaled gasses, or otherwise identifying characteristics of an image that correspond to the desired object to be detected.
 For example, various analysis and processing operations may be performed on the captured thermal images to detect and track objects such as a person, and determine various attributes associated with the detected object and/or the scene. In one embodiment, regions of contiguous pixels having temperature values in a specific range may be detected from radiometrically calibrated thermal images for detection and of the object. For example, the detection operation may differentiate a region (or a "blob") having a surface temperature distribution that is characteristic of a human. The thermal images and the blob detected therein may be further processed and/or analyzed, for example, by performing various filtering operations and analyzing the size, shape, and/or thermal characteristics of the blobs, to ascertain the detection of the person and to further localize the person. In some embodiments, features of a person such as face and facial features may also be detected. As described above with respect to FIG. 15, various features of a person (e.g., facial features such as the eyes, mouth, and nostrils, clothed portions, or objects the person may be holding) generally exhibit various corresponding temperatures. Thus, in one example, filtering operations such as dilation and threshold filtering performed on the detected blob may be utilized to further localize the features. Also, the size, shape, and/or radiometric properties of the localized features may be further analyzed, if needed, to ascertain the detection of the features.
 In another embodiment, the thermal images may be analyzed to detect one or more candidate foreground objects, for example, using background modeling techniques, edge detection techniques, or other foreground object detection techniques suitable for use with thermal images. The radiometric properties (e.g., surface temperature distribution) of the candidate objects may then be analyzed to determine whether they correspond to those of person that may be present in the scene. For example, rocks or trees may initially be detected as a candidate foreground object, but radiometric properties of the objects may then quickly reveal that it does not have a surface temperature distribution characteristic of a person and thus is not a person. As this example shows, object detection using the thermal images may be less susceptible to false detection of spurious objects compared with object detection techniques using visible light images. The size and shape of the candidate objects may also be analyzed, so that the detection may be ascertained based on the size, the shape, and the radiometric properties of the detected candidates. As described above, further processing and analysis operations may be performed if needed to localize and track the features of the person.
 In one aspect of this embodiment, background modeling techniques may be used to detect objects in the scene. Because the background of the scene rarely changes and because thermal images are generally insensitive to changing lighting conditions, a background model (e.g., pixels that belong to a background) may be constructed with high accuracy, and a region of pixels different from the background (also referred to as a "region of interest") may easily be distinguished as a candidate foreground object. As described above, the radiometric properties of such a region of interest (ROI) may then be analyzed to further ascertain whether the detected ROI likely represent a person.
 In various embodiments, the various processing and analysis operations described for block 2606 may be omitted or included, and may be performed in any other order as appropriate for detecting a person. For example, in some embodiments, detecting a warm "blob" in the thermal images may be sufficient to detect and track a person in a scene, whereas in other embodiments various thermal image analytics may be performed in combination to increase the accuracy of the detection.
 In some embodiments, if visible light images are available (e.g., captured by visible light camera 1406), operations for block 2606 may additionally or alternatively involve performing suitable face detection and tracking algorithms on the visible light images or combined images of the visible light images and the thermal images. If the detection and tracking of the face and facial features are performed using the visible light images, operations for block 2606 may further involve converting pixel coordinates of the tracked face and facial features in the visible light images to corresponding pixel coordinates in the thermal images. Other appropriate techniques for detecting objects in the thermal images by analyzing the thermal images, visible light images, and/or combined images may also be utilized for block 2606.
 At block 2608, the location of one or more detected objects (e.g., a detected person, more than one detected person, a detected animal, etc.) may be determined. Determining the location of a detected object may include determining which of several imaging modules captured an image in which the object was detected. In some embodiments, determining the location of the detected object may include determining the location of the object within an image captured by a given imaging module in order to further localize the determined location. Determining the location of the object within a captured image may include determining which pixels in the image include the object. Determining the location of the detected object may include determining an angular position of the object in a reference frame of the wearer of the wearable imaging device. For example, a reference frame of the wearer may have an angular position of zero degrees for forward locations directly in front of the wearer. In this example, an object behind the wearer may have an angular position of plus or minus 180 degrees. However, this is merely illustrative. If desired, angular positions of detected objects may be determined in any suitable reference frame or coordinate system such as a reference frame that is fixed to the physical environment surrounding the wearer.
 Determining the location of the detected object may also include determining a distance to the object from the wearable imaging device. Determining the distance to the object may include determining a size of the object in an image, determining a type of object (e.g., a human), determining a typical size for that type of object, and computing a distance based on the size of the object in the image and the typical size of the object. Determining the distance to the object may include determining the size and type of other objects such as background objects with known or typical sizes in captured thermal and/or visible images. Determining the distance to the object may include determining the distance to the object using stored scale and/or perspective calibration data.
 In some embodiments, additional object information may be determined at block 2608 by further analysis and processing and/or during the processing and analysis performed for detection. For example, the approximate body temperature, the approximate ambient temperature, and the posture of a detected person may be determined by analyzing and processing the thermal images as described above in connection with FIGS. 17-20 (as examples).
 At block 2610, an alert such as a location-specific alert associated with detected objects and their determined locations may be generated. Location-specific alerts may be generated using alert components 1702 as described above in connection with FIGS. 17-25 (as examples). For example, an alert component that is co-located with (e.g., adjacent to) an imaging module with which the object was detected may be operated to alert the wearer of a wearable imaging device of the presence of the detected object in the direction monitored by that imaging module. For example, a soldier wearing a multidirectional threat monitoring helmet may feel a vibration, hear a noise, see a light, or feel heat (as examples) on the right side of their head that indicates that a potential threat has been detected using thermal images captured using an infrared imaging module on the right side of the helmet. Generating the location-specific alert may include generating an alert using a single alert component or more than one alert component. Generating an alert using multiple alert components may allow the wearable imaging device to generate an alert for a wearer that seems to be generated at a location between the multiple alert components.
 If desired, the location-specific alert can have an intensity that indicates the distance to the detected object as described above in connection with, for example, FIG. 24. For example, a low intensity vibration or a gentle heat may indicate a detected threat at a relatively large distance and a high intensity vibration or an intense heat may indicate a detected threat at a relatively close distance.
 As further described above, the various attributes of thermal and/or visible light images may be further analyzed and/or processed to generate alerts for a wearer to warn of a particular posture, a posture change, a change in proximity, a violation of a virtual perimeter, or other suitable attributes.
 At block 2612, a user-viewable image of a detected object (or a scene containing a detected object) may be generated and displayed to the wearer. In one embodiment, the user-viewable image may be generated by converting thermal images using appropriate methods and algorithms. For example, thermal data (e.g., temperature data) contained in the pixels of the thermal images may be converted into gray-scaled or color-scaled pixels to construct images that can be viewed by a person. The user-viewable thermal images may optionally include legends or scales that indicate the approximate temperatures and/or locations of detected objects as described above in connection with, for example, FIG. 25. Generating the user-viewable image may include stitching together image data from multiple imaging modules, combining thermal and visible light images, or otherwise processing or combining image data to generate user viewable images. Displaying the user-viewable images may include providing the user-viewable images to a display of the wearable imaging system, or to an external display associated with another system.
 As indicated by arrow 2609, at block 2614, detected object information (e.g., a detected object notification, a detected object location, a detected object type, a detected object distance, a detected object feature, a detected object posture, a user-viewable image of a detected object, or other information associated with a detected object such as a person) may be communicated to other wearable imaging devices such as other multidirectional threat monitoring helmets. For example, a group of soldiers may be patrolling an area at night when a potential threat is detected using an imaging module on the left side of a particular soldier's helmet. That soldier may receive an alert from one or more alert components on the left side of his or her helmet and an alert notification may be transmitted wirelessly to the multidirectional threat monitoring helmets worn by other soldiers in the group. If desired, the multidirectional threat monitoring helmets of the other soldiers may also generate an alert for their wearers that indicates the presence and location of the detected object.
 In one embodiment, the generated monitoring information may be converted, wrapped, structured or otherwise formatted for data exchange with other wearable imaging devices using suitable application layer protocols (e.g., Simple Object Access Protocol (SOAP), Hypertext Transfer Protocol (HTTP)) or a proprietary data exchange format.
 Referring now to FIG. 27, a flowchart is illustrated of a process 2700 for monitoring moving objects and alerting a wearer to the location of the moving object using a wearable imaging device such as wearable imaging device 1700.
 At block 2702, thermal images of a scene may be captured using a plurality of infrared imaging modules mounted on a wearable structure of a wearable imaging device such as a multidirectional threat monitoring helmet.
 At block 2704, imaging processing operations of the type described above in connection with block 2604 of FIG. 26 may be performed on the captured thermal images.
 At block 2706, a moving object (e.g., a moving person or animal) may be detected using thermal images from a first one of the infrared imaging modules. A moving object may be detected in thermal images as described above in connection with block 2606 of FIG. 26.
 At block 2708, an alert such as a location-specific alert may be generated using an alert component of the wearable imaging device that is associated with the first one of the infrared imaging modules. For example, an alert may be generated using an alert component that is located near the position of the first one of the infrared imaging modules.
 At block 2710, the moving object may be detected using images from a second one of the infrared imaging modules. For example, the moving object may move out of the field of view of the first imaging module and into the field of view of the second imaging module.
 At block 2712, a second alert such as a second location-specific alert may be generated using a second alert component of the wearable imaging device that is associated with the second one of the infrared imaging modules. For example, a second alert may be generated using a second alert component that is located near the position of the second one of the infrared imaging modules (e.g., located closer to the second one of the infrared imaging modules than to the first one of the infrared imaging modules).
 Although various image processing techniques have been described, any of the various processing techniques set forth in any of the patent applications referenced herein may be used. For example, in some embodiments, visible images and/or thermal images may be blended or otherwise combined in accordance with any of the techniques set forth in U.S. Patent Application Nos. 61/473,207, 61/746,069, 61/746,074, 61/792,582, 61/793,952, Ser. Nos. 12/766,739, 13/105,765, or 13/437,645, or International Patent Application No. PCT/EP2011/056432, or others as appropriate.

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