Patent Publication Number: US-2022222919-A1

Title: Multi-camera device

Description:
RELATED APPLICATIONS 
     The patent arises from a continuation of U.S. patent application Ser. No. 16/937,204, entitled “MULTI-CAMERA DEVICE,” filed Jul. 23, 2020, which is a continuation of U.S. patent application Ser. No. 16/586,095 (now U.S. Pat. No. 10,726,296), entitled “MULTI-CAMERA DEVICE,” filed Sep. 27, 2019, which is a continuation of U.S. patent application Ser. No. 15/900,359 (now U.S. Pat. No. 10,460,202), entitled “MULTI-CAMERA DEVICE,” filed Feb. 20, 2018, which is a continuation of U.S. patent application Ser. No. 15/617,816 (now U.S. Pat. No. 9,898,684), entitled “MULTI-CAMERA DEVICE,” filed Jun. 8, 2017, which is a divisional application of U.S. patent application Ser. No. 14/818,987 (now U.S. Pat. No. 9,710,724), entitled “MULTI-CAMERA DEVICE,” filed Aug. 5, 2015, which is a non-provisional application of U.S. Provisional Application No. 62/046,398, entitled “Multi-Camera Device,” filed on Sep. 5, 2014. The present application claims priority to the Ser. Nos. 16/937,204, 16/586,095, 15/900,359, 15/617,816, 14/818,987, and the 62/046,398 application. The Ser. Nos. 16/937,204, 16/586,095, 15/900,359, 15/617,816, 14/818,987, and the 62/046,398 application are hereby fully incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to the field of photography, in particular, to apparatuses, methods and storage medium associated with multi-camera devices for depth photography and/or depth video applications. 
     BACKGROUND 
     The background description provided herein is for the purpose of generally presenting the context of the disclosure. Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section. 
     Depth photography and depth video applications require multi-camera devices with 2 or more world-facing cameras. Further, for proper multi-camera, depth mode operation, the 2 or more world-facing cameras need to be running concurrently with their captured frames synchronized and numbered in sequence. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments will be readily understood by the following detailed description in conjunction with the accompanying drawings. To facilitate this description, like reference numerals designate like structural elements. Embodiments are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings. 
         FIG. 1  illustrates a user facing view and a world facing view of a multi-camera device of the present disclosure for depth photography and depth video applications, in accordance with embodiments. 
         FIG. 2  illustrates a front view of the multi-camera device, further depicting placement of a soft shutter button, in accordance with embodiments. 
         FIG. 3  illustrates another front view of the multi-camera device, depicting viewfinders of the multi-camera device, in accordance with embodiments. 
         FIG. 4  illustrates still another front view of the multi-camera device, depicting provision of an alert when one or more of the camera sensors are blocked or obscured, in accordance with embodiments. 
         FIG. 5  illustrates a process for determining occlusion, blocking of a camera sensor, in accordance with embodiments. 
         FIG. 6  illustrates a block diagram of the multi-camera device of  FIGS. 1-5 , in accordance with various embodiments. 
         FIG. 7  illustrates an example storage medium with instructions configured to enable a multi-camera device to practice the present disclosure, in accordance with various embodiments. 
         FIG. 8  illustrate a function block view of the camera logic, in accordance with various embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Apparatuses, methods and storage medium associated with multi-camera devices are disclosed herein. In embodiments, a multi-camera device may include 3 or more camera sensors disposed on a world facing side of the multi-camera device for depth photography or depth video applications. Further, the multi-camera device may be configured to provide a soft shutter button to be disposed at a location on an opposite side to the world facing side, coordinated with locations of the 3 or more camera sensors that reduces likelihood of blocking of one or more of the 3 or more camera sensors. When the soft shutter button is activated, the multi-camera device operates with all camera sensors sensing concurrently and their captured frames synchronized and numbered in sequence. 
     In embodiments, the 3 or more camera sensors may include one high resolution camera sensor and two stereo camera sensors, and the multi-camera device is further configured with view finder logic to provide a main view finder for the one high resolution camera sensor, and two picture-in-picture viewfinders for the two stereo camera sensors. 
     Still further, in embodiments, the multi-camera device may include blocking determination logic to determine whether one or more of the 3 or more camera sensors is blocked, and provide an alert if at least one of the 3 or more camera sensors is blocked. 
     In the description to follow, reference is made to the accompanying drawings which form a part hereof wherein like numerals designate like parts throughout, and in which is shown by way of illustration embodiments that may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of embodiments is defined by the appended claims and their equivalents. 
     Operations of various methods may be described as multiple discrete actions or operations in turn, in a manner that is most helpful in understanding the claimed subject matter. However, the order of description should not be construed as to imply that these operations are necessarily order dependent. In particular, these operations may not be performed in the order of presentation. Operations described may be performed in a different order than the described embodiments. Various additional operations may be performed and/or described operations may be omitted, split or combined in additional embodiments. 
     For the purposes of the present disclosure, the phrase “A and/or B” means (A), (B), or (A and B). For the purposes of the present disclosure, the phrase “A, B, and/or C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C). 
     The description may use the phrases “in an embodiment,” or “in embodiments,” which may each refer to one or more of the same or different embodiments. Furthermore, the terms “comprising,” “including,” “having,” and the like, as used with respect to embodiments of the present disclosure, are synonymous. 
     As used hereinafter, including the claims, the term “module” may refer to, be part of, or include an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and/or memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality. 
       FIG. 1  illustrates a user facing view and a world facing view of a multi-camera device of the present disclosure, in accordance with embodiments. As illustrated, in embodiments, multi-camera device  100  may include 3 camera sensors  106  co-disposed on a world facing side of multi-camera device  100  for depth photography or depth video applications during a depth camera mode of operation. A main one of the 3 camera sensors  106  may be employed for conventional photography during a single camera mode of operation. 
     Unlike traditional smartphones or computing tablets where the shutter button is typically horizontally centered and below the centerfold of the device, the position of the shutter button  104  of multi-camera device  100  intelligently accounts for the physical locations of the world-facing camera sensors. More specifically, in embodiments, multi-camera device  100  may be configured to provide a soft shutter button  102  at a location on an opposite side to the world facing side, the user facing side, coordinated with locations of the 3 camera sensors  106  that reduce likelihood of blocking of one or more of the 3 camera sensors  106 . The user facing side may also be referred to as the front side of multi-camera device  100 , and the world facing side may be referred to as the rear or back side of multi-camera device  100 . 
     In embodiments, the 3 camera sensors  106  may include one high resolution camera sensor (8MP) and two stereo camera sensors (720p). All 3 camera sensors, the high resolution camera sensor (8MP) and the two stereo camera sensors (720p) are employed during the depth camera mode of operation and are synchronized by logic to concurrently capture multiple frames with identical frame sequence numbers, whereas only the high resolution camera sensor (8MP) is employed during the single camera mode of operation. In embodiments, the 3 camera sensors  106  may be arranged in a triangular pattern with the high resolution camera sensor (8MP) disposed proximally at the center of a side edge, and the two stereo camera sensors (720p) disposed proximally near the side edge at the top and bottom edges. 
     In embodiments, multi-camera device  100  may be configured with camera logic to place the soft shutter button  102  (also referred to as trigger) at the lower right corner of the user facing (front) side of multi-camera device  100  to guide a user in holding the multi-camera device  100  to reduce the likelihood of the user&#39;s hands or fingers blocking one or more of the 3 camera sensors  106 . See also  FIG. 2  for the complementary placement of the soft shutter button  102  or trigger, when the multi-camera device  100  is operated in a landscape orientation. When the soft shutter button is activated, the multi-camera device operates with all camera sensors sensing concurrently and their captured frames synchronized and numbered in sequence. 
     Referring now to  FIG. 3 , wherein another user facing or front view of multi-camera device  100 , in accordance with embodiments, is illustrated. As shown, in embodiments, multi-camera device  100  may be configured with camera logic (e.g., view finder logic) to provide a main view finder  302  for the one high resolution camera sensor, and two picture-in-picture viewfinders  304   a  and  304   b  for the two stereo camera sensors. 
     In embodiments, multi-camera device  100  may be configured with a camera preview window (not shown) for a user to select the depth camera mode of operation or the single camera mode of operation. In response to a user selecting the depth camera mode, a new preview display that shows all of the camera sensors  106  in real-time will be presented. The background of the main preview surface  302  will display the main high resolution camera frame, while two smaller picture-in-picture windows  304   a  and  304   b  will display the stereo camera previews. 
     Referring now to  FIG. 4 , wherein still another user facing or front view of multi-camera device  100 , in accordance with embodiments, is illustrated. As shown, in embodiments, the multi-camera device  100  may be configured with camera logic (e.g., blocking determination logic) to determine whether one or more of the 3 camera sensors  106  is blocked or obscured by either the user&#39;s hands, fingers or by another object, and provide an alert  102  if at least one of the 3 camera sensors  106  is blocked. In alternate embodiments, in addition to or in lieu of a visual alert  102 , an audio and/or mechanical alert, such as vibration, may be provided. 
     In embodiments, in response to a user selection of the depth camera mode, the multi-camera device  100  may switch from the single camera mode to the multi-camera mode operation. At this time, a scan may begin to evaluate if any or all of the stereo cameras  106  are being blocked or obscured. If a block or obscure state is flagged, an alert message in the camera preview (or a sound/voice or vibration alert) may be provided to indicate that the multi-camera device  100  is blocked or obscured. In embodiments, the alert message and/or signals may continue and not go away until the user has adjusted their hands, fingers or any object, unblocking all the multi-camera sensors  106 . 
     In embodiments, multi-camera device  100  may be configured to perform a threshold scan of the preview image to determine if one or more of camera sensors  106  is blocked, thus ensuring all three world-facing camera sensors are unobscured at the same time for depth photography or depth video application. 
       FIG. 5  illustrates a process for determining occlusion, blocking or obscuring of one or more of the camera sensors, in accordance with embodiments. Process  500  may be performed by e.g., a camera application within multi-camera device  100 . 
     At blocks  502  and  504 , RGB images of two stereo camera sensors may be received. 
     At block  505 , the images of the two camera may be smoothed, e.g., using a Gaussian kernel. At block  506 , the images of the two cameras may be down-sampled, e.g. to 80×45. 
     At block  508 , the down-sampled images may be converted to CIE-LAB color space images (CIE=International Commission on Illumination). 
     At block  510 , color histograms for both a and b channel may be built for both images. 
     At block  512 , the two histograms may be compared using l 1  or X 2  distance, where l 1  stands for the distance of the histograms, and X 2  stands for the Chi-Squared distances of the histograms. 
     At block  514 , a determination may be made on whether the distance is greater than a threshold? The threshold value may vary dependent on applications, e.g., quality desired, and/or lighting environments, low light and/or high, intense, reflective light environments. The threshold values may be empirically determined. 
     At block  516 , if a result of the determination indicates that the threshold is exceeded, an occlusion, i.e. blocking, conclusion may be drawn. Further, on conclusion of occlusion, an alert action (audio, visual, and/or mechanical) may be taken as earlier described. 
     At block  518 , on the other hand, if a result of the determination indicates that the threshold is not exceeded, no occlusion, i.e. blocking, conclusion may be drawn. 
     Before further describing multi-camera device  100 , it should be noted that while for ease of understanding, multi-camera device  100  has been described as having 3 camera sensors  106 , the present disclosure is not so limited. In alternate embodiments, multi-camera device  100  may be configured with more than 3 camera sensors. 
     Referring now to  FIG. 6 , wherein a block diagram of the multi-camera device  100  of  FIG. 1 , in accordance with various embodiments, is illustrated. As shown, multi-camera device  100  may include one or more processors or processor cores  602 , and system memory  604 . In embodiments, multiples processor cores  602  may be disposed on one die. For the purpose of this application, including the claims, the terms “processor” and “processor cores” may be considered synonymous, unless the context clearly requires otherwise. Additionally, multi-camera device  100  may include mass storage device(s)  606  (such as solid state drives), input/output device(s)  608  (such as camera sensors  106 , display, and so forth) and communication interfaces  610  (such as network interface cards, modems and so forth). In embodiments, the display may be touch sensitive. In embodiments, communication interfaces  610  may support wired or wireless communication, including near field communication. The elements may be coupled to each other via system bus  612 , which may represent one or more buses. In the case of multiple buses, they may be bridged by one or more bus bridges (not shown). 
     Each of these elements may perform its conventional functions known in the art. In particular, system memory  604  and mass storage device(s)  606  may be employed to store a working copy and a permanent copy of the programming instructions implementing the operations described earlier, e.g., but not limited to, operations associated with placement of the shutter button, provision of the previews, determination of blocking, provision of alert, capturing frames, synchronization of captured frames, numbering the synchronized frames in sequence, and so forth, denoted as camera logic  622 . The various elements may be implemented by assembler instructions supported by processor(s)  602  or high-level languages, such as, for example, C, that can be compiled into such instructions. 
     The permanent copy of the programming instructions may be placed into permanent mass storage device(s)  606  in the factory, or in the field, through, for example, a distribution medium (not shown), such as a compact disc (CD), or through communication interface  610  (from a distribution server (not shown)). 
     The number, capability and/or capacity of these elements  610 - 612  may vary, depending on the intended use of example multi-camera device  100 , e.g., whether example multi-camera device  100  is a smartphone, tablet, ultrabook, or a laptop. The constitutions of these elements  610 - 612  are otherwise known, and accordingly will not be further described. 
       FIG. 7  illustrates an example non-transitory computer-readable storage medium having instructions configured to practice all or selected ones of the operations associated with operations associated with placement of the shutter button, provision of the previews, determination of blocking, provision of alert, and so forth, earlier described, in accordance with various embodiments. As illustrated, non-transitory computer-readable storage medium  702  may include a number of programming instructions  704 . Programming instructions  704  may be configured to enable a device, e.g., multi-camera device  100 , in response to execution of the programming instructions, to perform, e.g., various operations associated with placement of the shutter button, provision of the previews, determination of blocking, provision of alert, capturing frames, synchronization of captured frames, numbering the synchronized frames in sequence, and so forth, described with references to  FIGS. 1-5 . In alternate embodiments, programming instructions  704  may be disposed on multiple non-transitory computer-readable storage medium  702  instead. In still other embodiments, programming instructions  704  may be encoded in transitory computer readable medium, such as signals. 
     Referring back to  FIG. 6 , for one embodiment, at least one of processors  602  may be packaged together with a computer-readable storage medium having camera logic  622  (in lieu of storing in system memory  604  and/or mass storage device  606 ) configured to practice all or selected ones of the operations earlier described with references to  FIG. 1-5 . For one embodiment, at least one of processors  602  may be packaged together with a computer-readable storage medium having camera logic  622  to form a System in Package (SiP). For one embodiment, at least one of processors  602  may be integrated on the same die with a computer readable storage medium having camera logic  622 . For one embodiment, at least one of processors  602  may be packaged together with a computer-readable storage medium having camera logic  622  to form a System on Chip (SoC). For at least one embodiment, the SoC may be utilized in, e.g., but not limited to, a hybrid computing tablet/laptop. 
     Referring now to  FIG. 8 , wherein a function block view of the camera logic, in accordance with various embodiments, is shown. As illustrated, in embodiments, camera logic  622  may include main engine  802 , and a number of auxiliary function blocks, such as occlusion function block  804 , alert function block  806 , and setting function block  808 . Main engine  802  may be configured with the main logic to operate multi-camera device  100 , including, but are not limited to, operation mode selection, soft shutter placement, preview, capturing of image, synchronization of captured frames, numbering the synchronized frames in sequence, and so forth. Occlusion function block  804  may be configured to determine obstruction/occlusion as earlier described. Alert function block  806  may be configured to provide alert as earlier described. Setting function block  808  may be configured to set various configuration parameters, including, but are not limited to, threshold values for determining occlusion, alert preferences, and so forth. In alternate embodiments, camera logic  622  may include more or less functions distributed in more or less function blocks. 
     Example 1 may be a multi-camera device, comprising: 3 or more camera sensors disposed on a world facing side of the multi-camera device; and a soft shutter button to be disposed on an opposite side to the world facing side, at a location coordinated with locations of the 3 or more camera sensors that reduces likelihood of a user of the multi-camera device blocking one or more of the 3 or more camera sensors. 
     Example 2 may be example 1, wherein the 3 or more camera sensors are disposed in a triangular pattern on one edge of the world facing side of the multi-camera device, and the soft shutter button may be disposed in a lower corner of an opposite edge of the opposite side. 
     Example 3 may be example 2, wherein a first of the 3 or more camera sensors may be disposed proximally at a center location of a side edge of the world facing side of the multi-camera device, a second of the 3 or more camera sensors may be disposed proximally at a location biased towards the side edge, at a top edge of the world facing side of the multi-camera device, and a third of the 3 or more camera sensors may be disposed proximally at a location biased towards the side edge, at a bottom edge of the world facing side of the multi-camera device. 
     Example 4 may be example 3, wherein the first camera sensor has a first resolution, and the second and third camera sensors have second and third resolutions that are lower than the first resolution. 
     Example 5 may be example 4, wherein the second and third camera sensors form a stereo camera pair. 
     Example 6 may be example 4, wherein the first camera sensor has a first resolution of 8MP, and the second and third camera sensors have second and third resolutions, both of 720p. 
     Example 7 may be example 4, further comprising view finder logic to provide a main view finder for the first camera sensor. 
     Example 8 may be example 7, wherein the multi-camera device has at least a single camera mode of operation, and the view finder logic may provide the main view finder in at least the single camera mode of operation. 
     Example 9 may be example 8, wherein the multi-camera device has at least another depth camera mode of operation, and the view finder logic may also provide the main view finder during the depth camera mode of operation. 
     Example 10 may be example 7, wherein the view finder logic to further provide two picture-in-picture viewfinders for the second and third camera sensors. 
     Example 11 may be example 10, wherein the multi-camera device has at least a depth camera mode of operation, and the view finder logic may also provide the two picture-in-picture viewfinders during the depth camera mode of operation. 
     Example 12 may be any one of examples 1-11, further comprising blocking determination logic to determine whether one or more of the 3 or more camera sensors is blocked, and provide an alert, when at least one of the 3 camera sensors is determined to be blocked. 
     Example 13 may be example 12, wherein the alert may comprise a selected one of a visual alert, an audio alert or a mechanical alert. 
     Example 14 may be example 12, wherein the blocking determination logic may receive and analyze images from at least 2 of the 3 or more cameras to determine whether one or more of the 3 or more camera sensors is blocked. 
     Example 15 may be example 14, wherein to analyze images from at least 2 camera sensors, the blocking determination logic may build respective histograms for one or more color channels for the images, and compare the histograms. 
     Example 16 may be example 15, wherein to compare the histograms, the blocking determination logic may compute distances of the histograms. 
     Example 17 may be example 14, wherein to analyze images from at least 2 camera sensors, the blocking determination logic may smooth or down sample the images. 
     Example 18 may be at least one computer-readable storage medium comprising a plurality of instructions configured to cause a multi-camera device having 3 or more camera sensors, in response to execution of the instructions by the multi-camera device, to provide a soft shutter button at a location on an opposite side to a world facing side of the multi-camera device where the 3 or more camera sensor are disposed, wherein the location of the soft shutter button may be selected in view of locations of the 3 or more camera sensors on the world facing side to reduce likelihood of a user of the multi-camera device blocking one or more of the 3 or more camera sensors. 
     Example 19 may be example 18, wherein the 3 or more camera sensors are disposed in a triangular pattern on one edge of the world facing side of the multi-camera device, and the multi camera device may be caused to place the soft shutter button in a lower corner of an opposite edge of the opposite side. 
     Example 20 may be example 18, wherein a first of the 3 or more camera sensors has a first resolution, and a second and a third of the 3 or more camera sensors have a second and a third resolution that are lower than the first resolution; wherein the multi-camera device may be further caused to provide a main view finder for the first camera sensor, and two picture-in-picture viewfinders for the second and third camera sensors. 
     Example 21 may be example 20, wherein the multi-camera device has at least a single camera mode of operation, and the multi-camera device may be caused to provide the main view finder in at least a single camera mode of operation. 
     Example 22 may be example 21, wherein the multi-camera device has at least another depth camera mode of operation, and the multi-camera device may be caused to also provide the main view finder during the depth camera mode of operation. 
     Example 23 may be example 20, wherein the multi-camera device has at least a depth camera mode of operation, and the multi-camera device may provide the two picture-in-picture viewfinders during the depth camera mode of operation. 
     Example 24 may be any one of examples 18-23, wherein the multi-camera device may be further caused to determine whether one or more of the 3 or more camera sensors is blocked, and provide an alert, when at least one of the 3 or more camera sensors is blocked. 
     Example 25 may be example 24, wherein the multi-camera device may be further caused to provide one or more of a visual alert, an audio alert or a mechanical alert, when at least one of the 3 or more camera sensors may be blocked. 
     Example 26 may be example 24, wherein the multi-camera device may be further caused to analyze images from at least 2 of the 3 or more cameras to determine whether one or more of the 3 or more camera sensors is blocked. 
     Example 27 may be example 26, wherein the multi-camera device may be further caused to build respective histograms for one or more color channels for the images, and compare the histograms, to analyze images from at least 2 camera sensors. 
     Example 28 may be example 27, wherein the multi-camera device may be further caused to compute distances of the histograms, to compare the histograms. 
     Example 29 may be example 26, wherein the multi-camera device may be further caused to smooth or down sample the images, to analyze images from at least 2 camera sensors. 
     Example 30 may be a method for operating a multi-camera device, comprising: providing, by the multi-camera device, a soft shutter button at a location on an opposite side to a world facing side of the multi-camera device where 3 or more camera sensors are disposed, wherein the location may be coordinated with location of the 3 or more camera sensors to reduce likelihood of blocking one or more of the 3 or more camera sensors; determining, by the multi-camera device, whether one or more of the 3 or more camera sensors is blocked; and providing, by the multi-camera device, an alert when a result of the determination indicates at least one of the 3 or more camera sensors is blocked. 
     Example 31 may be example 30, wherein providing an alert may comprise providing, by the multi-camera device, a selected one of a visual alert, an audio alter or a mechanical alert. 
     Example 32 may be example 30 or 31, wherein a first of the 3 camera sensors has a first resolution, and a second and a third of the 3 camera sensors have a second and a third resolution that are lower than the first resolution; wherein the method may further comprise providing a main view finder for the first camera sensor, and two picture-in-picture viewfinders for the second and third camera sensors. 
     Example 33 may be example 32, wherein the multi-camera device has at least a single camera mode of operation, and providing the main view finder may comprise providing the main view finder in at least a single camera mode of operation. 
     Example 34 may be example 33, wherein the multi-camera device has at least another depth camera mode of operation, and providing the main view finder may comprise providing the main view finder during the depth camera mode of operation. 
     Example 35 may be example 32, wherein the multi-camera device has at least a depth camera mode of operation, and providing the two picture-in-picture view finders may comprise providing the two picture-in-picture viewfinders during the depth camera mode of operation. 
     Example 36 may be example 30 or 31, wherein determining whether one or more of the 3 or more camera sensors is blocked may comprise analyzing images from at least 2 of the 3 or more cameras to determine whether one or more of the 3 or more camera sensors is blocked. 
     Example 37 may be example 36, wherein analyzing images from at least 2 camera sensors may comprise building respective histograms for one or more color channels for the images, and comparing the histograms. 
     Example 38 may be example 37, wherein comparing the histograms may comprise computing distances of the histograms. 
     Example 39 may be example 38, wherein analyzing images from at least 2 camera sensors comprises smoothing or down sampling the images. 
     Example 40 may be a multi-camera apparatus, comprising: 3 or more camera sensors disposed on a world facing side of the multi-camera apparatus; and means for providing a soft shutter button at a location at a location on an opposite side to the world facing side of the multi-camera apparatus, wherein the location may be coordinated with locations of the 3 or more camera sensors to reduce likelihood of blocking one or more of the 3 or more camera sensors. 
     Example 41 may be example 40, further comprising means for determining whether one or more of the 3 or more camera sensors is blocked; and means for providing an alert when a result of the determination indicates at least one of the 3 or more camera sensors is blocked. 
     Example 42 may be example 41, wherein means for providing an alert comprises means for providing a selected one of a visual alert, an audio alter or a mechanical alert. 
     Example 43 may be example 40, 41 or 42, wherein a first of the 3 camera sensors has a first resolution, and a second and a third of the 3 camera sensors have a second and a third resolution that are lower than the first resolution; wherein the apparatus further comprises means for providing a main view finder for the first camera sensor, and means for providing two picture-in-picture viewfinders for the second and third camera sensors. 
     Example 44 may be example 43, wherein the multi-camera apparatus has at least a single camera mode of operation, and means for providing the main view finder comprises means for providing the main view finder in at least a single camera mode of operation. 
     Example 45 may be example 44, wherein the multi-camera apparatus has at least another depth camera mode of operation, and means for providing the main view finder comprises means for providing the main view finder during the depth camera mode of operation. 
     Example 46 may be example 43, wherein the multi-camera apparatus has at least a depth camera mode of operation, and means for providing the two picture-in-picture view finders comprises means for providing the two picture-in-picture viewfinders during the depth camera mode of operation. 
     Example 47 may be example 41 or 42, wherein means for determining whether one or more of the 3 or more camera sensors is blocked comprises means for analyzing images from at least 2 of the 3 or more cameras to determine whether one or more of the 3 or more camera sensors is blocked. 
     Example 48 may be example 47, wherein means for analyzing images from at least 2 camera sensors comprises means for building respective histograms for one or more color channels for the images, and means for comparing the histograms. 
     Example 49 may be example 48, wherein means for comparing the histograms may comprise means for computing distances of the histograms. 
     Example 50 may be example 49, wherein means for analyzing images from at least 2 camera sensors may comprise means for smoothing or down sampling the images. 
     Although certain embodiments have been illustrated and described herein for purposes of description, a wide variety of alternate and/or equivalent embodiments or implementations calculated to achieve the same purposes may be substituted for the embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the embodiments discussed herein. Therefore, it is manifestly intended that embodiments described herein be limited only by the claims. 
     Where the disclosure recites “a” or “a first” element or the equivalent thereof, such disclosure includes one or more such elements, neither requiring nor excluding two or more such elements. Further, ordinal indicators (e.g., first, second or third) for identified elements are used to distinguish between the elements, and do not indicate or imply a required or limited number of such elements, nor do they indicate a particular position or order of such elements unless otherwise specifically stated.