Patent Publication Number: US-10326950-B1

Title: Image capture at multiple resolutions

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 15/271,333, which was filed on Sep. 21, 2016, which claims the benefit of U.S. Provisional Application No. 62/233,698, which was filed on Sep. 28, 2015, the contents of which are hereby incorporated by reference in its entirety for all purposes. 
    
    
     FIELD 
     The disclosure relates generally to the field of imaging devices. More particularly, the disclosure relates to capturing images at multiple resolutions using an imaging device. 
     BACKGROUND 
     Still images and video sequences are utilized as inputs by a variety of computing applications. These applications often operate in real-time, by receiving inputs from an image sensor. The characteristics of the required input are application specific. Some applications require high frame rate video, while other applications require high-resolution images. 
     Known solid-state image sensors can be controlled to operate at various resolutions and framerates. Generally, there is an inverse relationship between frame rate and resolution. High frame rate modes typically operate at low to moderate resolutions, while high-resolution modes typically operate at low to moderate frame rates. 
     SUMMARY 
     One aspect of the disclosed embodiments is a device for capturing an image. The device includes an image sensor having a plurality of sensing elements and a control circuit. The control circuit is configured to receive a first group of image signals from a first portion of the plurality of sensing elements using at least a first binned read mode; receive a second group of image signals from a second portion of the plurality of sensing elements using a non-binned read mode; generate a first image based on at least the first group of image signals and the second group of image signals; and generate a second image based on the second group of image signals. 
     Another aspect of the disclosed embodiments is a device for capturing an image. The device includes an image sensor having a plurality of sensing elements, a computing device, and a control circuit. The control circuit is configured to receive a first group of image signals from a first portion of the plurality of sensing elements using at least a first binned read mode, receive a second group of image signals from a second portion of the plurality of sensing elements using a non-binned read mode, generate a first image based on at least the first group of image signals and the second group of image signals, generate a second image based on the second group of image signals, and transmit the first image and the second image to the computing device over a single interface by interleaving the first image and the second image. 
     Another aspect of the disclosed embodiments is a device for capturing an image. The device includes an image sensor having a plurality of sensing elements and a control circuit. The control circuit is configured to receive a first group of image signals from a first portion of the plurality of sensing elements using at least a first binned read mode, receive a second group of image signals from a second portion of the plurality of sensing elements using a non-binned read mode, generate a first image based on at least the first group of image signals and the second group of image signals, generate a second image based on the second group of image signals, expose the first portion over a first integration time period, and expose the second portion over a second integration time period, wherein the first integration time period is shorter than the second integration time period. 
     Another aspect of the disclosed embodiments is a device for capturing an image. The device includes an image sensor having a plurality of sensing elements and a control circuit. The control circuit is configured to obtain a reference image using the image sensor, identify a window of interest using the reference image based on presence of at least one feature, identify a first portion of the image sensor that does not include the window of interest and a second portion of the image sensor that includes the window of interest, read a first group of image signals from the first portion of the image sensor using at least a first binned read mode, read a second group of image signals from a second portion of the image sensor using a non-binned read mode, generate a first image based on at least the first group of image signals and the second group of image signals by combining the first group of image signals with a downsampled version of the second group of image signals, and generate a second image that corresponds to the window of interest based on the second group of image signals. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The detailed description makes reference to the accompanying drawings, wherein like reference numerals refer to like parts through several views, and in which: 
         FIG. 1  is a block diagram showing an example of an imaging system; 
         FIG. 2  is a block diagram showing an example of a computing device; 
         FIG. 3  is an illustration showing an image; 
         FIG. 4  is a schematic illustration showing an image sensor; 
         FIG. 5  is a schematic illustration showing a portion of a line group from the image sensor; 
         FIG. 6  is a flowchart showing a process for reading an image sensor; and 
         FIG. 7  is a functional block diagram showing an apparatus. 
     
    
    
     DETAILED DESCRIPTION 
     In known systems, it is not practical for multiple applications to concurrently use a single image sensor to provide inputs when the applications require differing characteristics. The methods, systems, and devices described herein utilize a flexible read out scheme for an image sensor by which portions of an image sensor are read using differing read modes. For example, a first portion of an image sensor can be read using a first read mode, and a second portion of the image sensor can be read using a second read mode. The information read from the first portion of the image sensor can be combined with the information read from the second portion of the image sensor to generate a first output image, while a second output image is generated using at least part of the information read from the second portion of the image sensor. 
       FIG. 1  shows an imaging system  100  that includes an imaging device  110 . The imaging device  110  is an example of a device that can be utilized to implement the systems and methods described herein. In the illustrated example, the imaging device  110  includes a lens assembly  112 , a filter  114 , an image sensor  116 , a processing circuit  120 , a memory  122 , an interface  124 , and a control circuit  126 . It should be understood that these components are described by way of example, and that the systems and methods that are described herein can be implemented using imaging systems that differ from the imaging system  100 . 
     The imaging device  110  receives electromagnetic radiation from a scene  130  and generates information representing an image based on the received electromagnetic radiation. The scene  130  includes any source of visible electromagnetic radiation or non-visible electromagnetic radiation in at least the infrared portion of the electromagnetic spectrum within the field of view of the imaging device  110 . The output of the imaging device can be transmitted to an external device, such as a computing device  140 . The computing device  140  can be any manner of device that is able to receive, interpret, display, and/or store the output of the imaging device  110 . The computing device  140  may include instructions, whether encoded in hardware or stored in memory. As one example, the computing device  140  may include one or more processors and memory, such that the processor of the computing device  140  is operable to access information stored in the memory and execute program instructions stored in the memory. As another example, the computing device  140  can be or include one or more processors that are dedicated to the function of controlling the imaging device. As another example, the computing device may be a device such as a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC) that includes encoded instructions for controlling the imaging device. As another example, the computing device  140  can be a conventional computer of any type. 
     The lens assembly  112  of the imaging device  110  includes one or more lenses. The lens assembly  112  receives and directs at least visible and infrared electromagnetic radiation. In typical implementations, the lens assembly includes a plurality of lens elements, some of which may be manipulated mechanically to allow focusing and/or zooming. 
     The electromagnetic radiation that passes through the lens assembly  112  next passes through the filter  114 . The filter  114  is an element that controls the type of electromagnetic radiation that passes through it, by allowing passage of or blocking passage of electromagnetic radiation of particular wavelength ranges. In some implementations, the filter  114  is an array of filter elements that each allow or block passage of a different wavelength as compared to one or more neighboring filter elements in the array. As one example, if the imaging device  110  is intended to capture color images, the filter  114  can be a color filter array such as a Bayer filter. As another example, if the imaging device  110  is intended to capture infrared images, the filter  114  can be of a type that passes infrared radiation. As another example, if the imaging device  110  is intended to capture both visible images and infrared images, the filter  114  can include a pattern of filter elements including filter elements that pass certain wavelengths in the visible portion of the electromagnetic spectrum and filter elements that pass wavelengths in the infrared portion of the electromagnetic spectrum. 
     The image sensor  116  is a solid-state device that includes an array of sensing elements  118 . Each of the sensing elements  118  is operable to accumulate an electrical charge proportional to the amount of electromagnetic radiation incident upon it. The charge of each sensing element  118  can manipulated by the image sensor  116  to allow it to be amplified and read out as an analog image signal. As examples, the image sensor  116  can be a CCD image sensor or a CMOS image sensor. To control exposure of the sensing elements  118 , the image sensor  116  can include a global shutter or a rolling shutter. 
     The processing circuit  120  is operable to receive the analog image signals and store information in the memory  122  that represents the analog image signals. The processing circuit  120  can include, as examples, an analog-to-digital converter and a digital signal processor. The interface  124  is operable to access information stored in the memory  122  and transmit the information to an external component, such as the computing device  150 . 
     The interface  124  is also operable to receive information including instructions from the computing device  150 , and relay the information and/or instructions to the control circuit  126 . The control circuit  126  is operable to regulate operation of the image sensor  116 , such as by setting a read mode for the image sensor  116  and controlling the manner in which the analog image signals are collected and/or read by the image sensor  116 . 
       FIG. 2  shows an example of a computing device  200  that can be utilized as the computing device  150  of  FIG. 1 . The computing device  200  can be a single computing device, such as a desktop computer, a laptop computer, a tablet, or a mobile telephone. Alternatively, the computing device  200  can be a system that includes multiple computing devices working cooperatively. 
     In the illustrated example, the computing device  200  includes a processor  210 , a memory device  220 , a storage device  230 , one or more input devices  240 , and one or more output devices  250 , which are interconnected by a bus  260 . The computing device  200  can also include a bus interface  270  for connecting peripheral devices to the bus  260 . 
     The processor  210  can be any type of device that is able to process or manipulate information, including devices that are currently known and devices that may be developed in the future. As an example, the processor  210  can be a conventional central processing unit (CPU). Although the illustrated example shows a single processor, multiple processors can be utilized instead of a single processor. 
     The memory device  220  is utilized to store information for immediate use by the processor  210 . The memory device  220  includes either or both of a random access memory (RAM) device and a read only memory (ROM) device. The memory device  220  can be utilized to store information, such as program instructions that can be executed by the processor  210 , and data that is stored by and retrieved by the processor  210 . In addition, portions of the operating system of the computing device  200  and other applications that are being executed by the computing device  200  can be stored by the memory device during operation of the computing device  200 . 
     The storage device  230  is utilized to store large amounts of data persistently. As examples, the storage device  230  can be a hard disk drive or a solid-state drive. 
     The input devices  240  can include any type of device that is operable to generate computer interpretable signals or data in response to user interaction with the computing device  200 , such as physical interaction, verbal interaction, or non-contacting gestural interaction. As examples, the input devices  240  can include one or more of a keyboard, a mouse, a touch-sensitive panel with or without an associated display, a trackball, a stylus, a microphone, a camera, or a three-dimensional motion capture device. 
     The output devices  250  can include any type of device that is able to relay information in a manner that can be perceived by a user. As examples, the output devices  250  can include one or more of an LCD display screen, an LED display screen, a CRT display screen, a printer, an audio output device such as a speaker, or a haptic output device. In some implementations, the output devices  250  include a display screen and the input devices  240  include a touch sensitive panel that is integrated into the display screen to define a touch-sensitive display screen. 
     The bus  260  transfers signals and/or data between the components of the computing device  200 . Although depicted as a single bus, it should be understood that multiple or varying types of buses could be utilized to interconnect the components of the computing device  200 . The bus interface  270  can be any type of device that allows other devices, whether internal or external, to connect to the bus  260 . 
       FIG. 3  shows an example of an image  300  that includes a plurality of features. The image  300  can be a raster image that includes a plurality of pixels. 
     In the image  300 , each feature from a first group of features  310  corresponds to a first feature type and each feature from a second group of features  320  corresponds to a second feature type. In the illustrated example, the first group of features  310  includes two features and the first feature type is a star shape, while the second group of features  320  includes two features and the second feature type is a hexagonal shape. The number and types of features and groups of features can vary, however, and the specific numbers and types of features depicted in the illustrated example are chosen only for ease of description. 
     The first group of features  310  and the second group of features  320  can be identified using conventional feature extraction and classification techniques. Such feature extraction techniques can be implemented using a computing device such as the computing device  200 , which would receive the image  310  as an input. 
     A window of interest is defined around each of the features in the image. For example a first window of interest  331  can be defined around a first feature from the first group of features  310 , a second window of interest  332  can be defined around a second feature from the first group of features  310 , a third window of interest  333  can be defined around a first feature from the second group of features  320 , and a fourth window of interest  334  can be defined around a fourth feature from the fourth group of features  310 . In some instances, windows of interest may overlap, as is the case with the second window of interest  332  and the fourth window of interest  334  in the illustrated example. 
     The windows of interest identified using the image  300  can be utilized to control the manner by which information is read from an image sensor, such as an image sensor  400  as shown in  FIG. 4 . Controlling the manner by which information is read from the image sensor  400  can be performed by setting a read mode for the image sensor  400 . In one implementation, the read mode utilized for each of the windows of interest is dependent upon the feature type of the features within the respective window of interest. In the illustrated example, the first area  411  and the second area  412  correspond to the first feature type and are read with a first read mode, while the third area  413  and the fourth window of interest correspond to the second feature type and are read with a second read mode that is different than the first read mode. 
     Read modes for the image sensor  400  can vary in terms of characteristics such as resolution and rate, and read modes having different resolutions typically operate at different rates. For example, a highest possible resolution of the image sensor  400  can be obtained using a non-binned read mode in which the electrical charge accumulated by each of the image sensing elements of the image sensor is read out individually as an analog value. Thus, reading a portion of the image sensor  400  using the non-binned read mode generates a full-resolution image for that portion of the image sensor  400 . 
     Lower resolutions can be read directly from the image sensor  400  using a binned read mode in which the electrical charges accumulated by multiple sensing elements are combined and read out as a single analog value. As examples, binned read modes can include a 2×2 binned read mode in which electrical charges from four sensing elements are combined and read out as a single analog value, and a 4×4 binned read mode in which electrical charges from sixteen sensing elements are combined and read out as a single analog value. These examples are not an exhaustive list of read modes, as other read modes can be utilized to read information from the image sensor  400 . 
     By controlling the manner in which information is read from the image sensor  400 , such as by reading different portions of the image sensor  400  with different read modes multiple images having differing characteristics can be generated simultaneously. For example, the simultaneously generated images can include an image based on information from the entire image sensor  400 , as well as one or more additional images based on information from the image sensor  400  corresponding to one or more of the windows of interest. 
     The image sensor  400  can be configured as described with respect to the image sensor  116 , and can be incorporated in a device such as the imaging device  110 . The image sensor  400  includes an array of sensing elements (not shown in  FIG. 4 ) that are arranged in rows and columns. 
     Using information that identifies the first window of interest  331 , the second window of interest  332 , the third window of interest  333 , and the fourth window of interest  334 , corresponding areas of the image sensor  400  can be identified. In an implementation where the image  300  was previously captured using the image sensor  400 , the corresponding areas of the image sensor  400  are identified by mapping the spatial coordinates of the relevant window of interest to the image sensor  400 , such that the identified portion of the image sensor  400  includes the sensing elements that captured the portion of the image  300  that is disposed within the corresponding window of interest. In the illustrated example a first area  411 , a second area  412 , a third area  413  and a fourth area  414  of the image sensor  400  are identified as corresponding to the first window of interest  331 , the second window of interest  332 , the third window of interest  333 , and the fourth window of interest  334 . 
     The image sensor  400  can be subdivided into a plurality of line groups, where each line group includes one or more rows of sensing elements. For example, each line group could include four rows of sensing elements, and therefore have a height that corresponds to four sensing elements and a width that corresponds to the full width of the image sensor  400 . In the illustrated example, the line groups of the image sensor  400  include a first line group  421 , a second line group  422 , and a third line group  423 . 
     The presence or absence of a window of interest within a line group can be utilized to select a read mode. A window of interest is considered to be present within a line group if at least some of the sensing elements of the image sensor  400  that are included in the window of interest are included in the line group. In the illustrated example, there are no windows of interest present in first line group  421 , the first area  411  is present in the second line group  422 , and the first area  411  and the third area  413  are both present in the third line group  423 . 
     The read mode can be selected on a line group basis, with the entire line group being read using a single read mode. Where more than one read mode is applicable to a line group, a selection order can be defined to identify which read mode takes precedence when multiple are applicable. As an example, read modes having higher resolutions can take precedence over read modes having lower resolutions. Thus, the non-binned read mode can take precedence over the 2×2 binned read mode, and the 2×2 binned read mode can take precedence over the 4×4 binned read mode. 
     In the illustrated example, portions of the image sensor  400  that are not within one of the windows of interest correspond to a 4×4 binned read mode, portions of the image sensor  400  within the first area  411  and the second area  412  correspond to a 2×2 binned read mode, and portions of the image sensor  400  within the third area  413  and the fourth area  414  correspond to the non-binned read mode. Since the first line group  421  includes only portions of the image sensor  400  that are not within any window of interest, the first line group  421  is read with the 4×4 binned read mode. Since the second line group  422  includes portions of the image sensor  400  that are within the first area  411 , the second line group  422  is read using the 2×2 binned read mode, which corresponds to the first window of interest and takes precedence over the 4×4 binned read mode. The third line group  423  includes portions of the image sensor  400  that are within the first area  411  and portions of the image sensor  400  that are within the third area  413  and is read using the non-binned read mode, which corresponds to the third area  413  and takes precedence over the binned read modes. 
     Reading of the third line group  423  will be explained further with reference to  FIG. 5 . The third line group  423  includes a plurality of sensing elements  511  in an array that has a height equal to four of the sensing elements  511  and a width equal to the full width of the image sensor  400 . A portion of the sensing elements  511  are included within the third area  413 , a portion of the sensing elements  511  are included within the first area  411 , and the remainder of the sensing elements  511  are not included within any window of interest. 
     As previously noted, the third line group  423  is read using the non-binned read mode, analog values read from the image sensor  400  will include a respective value for each of the sensing elements  511  in the third line group  423 . The analog data values are converted to digital values as previously explained with respect to the processing circuit  410 . Of these digital values, the values that correspond to the sensing elements  511  within the third area  413  output in a manner that allows them to be used to define an image for the third area  413  when combined with values from other line groups. As examples, the values can be added to a memory space that corresponds to the third area  413  or the values can be added to a data stream. The values obtained from reading the third line group  423  are then downsampled to match the resolution of the 2×2 binned read mode. A portion of the downsampled values correspond to sensing elements  511  that are located within the first area  411 , and these values are output in a manner that allows them to be used to define an image for the first area  411  when combined with values from other line groups, such as by adding the values to a corresponding memory space or data stream. The downsampled data values are further downsampled to match the resolution of the 4×4 binning mode, and these values are output in a manner that allows them to be used to define an image for the entire image sensor  400  when combined with values from other line groups, such as by adding the values to a corresponding memory space or data stream. 
     In implementations where the image sensor  400  allows individual addressing of the sensing elements  511  or blocks of the sensing elements  511 , the manner of reading the third line group  423  can be modified by reading portions of the line group using different read modes instead of reading the entirety of the third line group  423  with a single read mode. In particular, the portion of the third line group  423  within the third area  413  can be read using the non-binned read mode, the portion within the first area  411  can be read using the 2×2 binned read mode, and the remaining portions of the third line group  423  can be read using the 4×4 binned read mode. Portions of the third line group  423  read using the non-binned read mode and/or the 2×2 binned read mode are downsampled and added to the data obtained using other read modes as needed. 
     Reading all of the line groups from the image sensor  400  will produce five images. One of the images corresponds to the entire area of the image sensor  400 . The other images each correspond to a respective one of the first area  411 , the second area  412 , the third area  413 , and the fourth area  414 . Portions of each of these images can be stored in a memory space while the image sensor  400  is read, with each image being stored in a separate memory space. As an example, in the imaging device  110 , these memory spaces can be defined in the memory  122 . The images can then be transferred using an interface, such as the interface  124  of the imaging device  110 . In one implementation, the images are transmitted to the computing device  200  using a single interface such as the interface  124  by interleaving the images. In another implementation, the interface  124  includes multiple separately addressable interfaces that can each be addressed by the computing device  200  as if it were a separate device. In this implementation, the images are each transmitted using a respective one of the separately addressable interfaces. 
     The systems and methods herein include combining image signals read using the non-binned read mode and one or more binned read modes to generate an image. Since binning operations combine the electrical charge from multiple sensing elements of the image sensor  400 , portions that of the image sensor  400  are read using binned read modes can be exposed over a shorter integration time periods as compared to non-binned read modes or higher resolution binned read modes in order to achieve similar exposure characteristics for portions of the image sensor  400  that are read using different read modes. In an example where a first portion of the image sensor  400  is read using the 2×2 binned read mode and a second portion of the image sensor  400  is read using the non-binned read mode, the first portion can be exposed over a first integration time period that is shorter than a second integration time period over which the second portion is exposed. In one implementation, different integration times can be achieved using a rolling shutter. 
       FIG. 6  shows an example of a process  600  for reading information from an image sensor. The process  600  can be implemented in an imaging device, and will be described with respect to implementation using the imaging device  110 . As an example, the process  600  can be implemented in the form instructions that are executed by the control circuit  126  and/or the processing circuit  120  of the imaging device  110 . 
     Operation  602  includes obtaining a reference image. The reference image can be obtained by capturing it using the imaging device as previously described. In operation  604 , one or more windows of interest (WOI) are identified, and information identifying the locations of the windows of interest is available to the device or devices that are implementing the process  600 . The windows of interest can be identified, for example, based on features found in the reference image using a feature identification algorithm. 
     In this example, areas outside of one of the windows of interest correspond to a 4×4 binned read mode, and the window of interest include a 2×2 binned window of interest that corresponds to the 2×2 binned read mode and a non-binned window of interest that corresponds to the non-binned read mode. 
     A portion of the image sensor  116  is selected at operation  610 . The portion selected can, for example, be the next available line group of the image sensor  116 . The selection made at operation  610  can be in any form that causes a new portion of the image sensor  116  to be made available for reading, and does not require a selection between multiple options. The portion selected can be of any suitable area of the image sensor, such as one or more lines, one or more line groups, one or more sensing elements, or one or more blocks of sensing elements. 
     In operation  620 , a determination is made as to whether a window of interest is present in the current portion of the image sensor  116 . If no window of interest is present in the current portion of the image sensor  116 , the process proceeds to operation  622 , where image signals for the current portion of the image sensor  116  are read using the 4×4 binned read mode. If one or more windows of interest are present in the current portion of the image sensor, the process proceeds to operation  630 . 
     In operation  630 , a determination is made as to whether one of the non-binned windows of interest is present in the current portion of the image sensor  116 . If no non-binned window of interest is present in the current portion of the image sensor  116 , the process proceeds to operation  632 , where image signals for the current portion of the image sensor are read using the 2×2 binned read mode. If one or more non-binned windows of interest are present in the current portion of the image sensor, the process proceeds to operation  640 . 
     In operation  640 , image signals for the current portion of the image sensor are read using the non-binned read mode. In operation  642 , the image signals read out from the image sensor in operation  640  are analyzed, and the portion of the image signals from sensing elements that fall within one of the non-binned windows of interest are added to full resolution image data corresponding to the respective window of interest. As one example, the image signals can be added to a memory space that corresponds to the window of interest, such as a memory space at the memory  122  of the imaging device  110 . As another example, the image signals can be added to a data stream. Thus, a portion of an image is defined in the memory space or data stream. 
     In operation  644 , the image signals read out from the image sensor  116  at operation  640  are downsampled. The image signals can be downsampled to a resolution equivalent to the resolution that would result from reading the image sensor  116  using the 2×2 binned read mode. This can be accomplished by performing a 2×2 digital bin operation with respect to the full resolution image signals read at operation  640 . The process then proceeds to operation  650 . 
     Operation  650  occurs after either of operation  632  or operation  644 , and utilizes image signals obtained either at operation  632  by reading the image sensor  116  using the 2×2 binned read mode or the downsampled image signals generated at operation  644 . In operation  650 , the portion of the image signals from sensing elements that fall within one of the 2×2 binned windows of interest are added to 2×2 binned data corresponding to the respective window of interest, such as in a memory space or a data stream. Thus, a portion of an image is defined in the memory space or data stream. 
     In operation  652 , the image signals utilized at operation  650  are downsampled. The image signals can be downsampled to a resolution equivalent to the resolution that would result from reading the image sensor  116  using the 4×4 binned read mode. This can be accomplished by performing a 2×2 digital bin operation with respect to the image signals utilized at operation  652 . The process then proceeds to operation  660 . 
     Operation  660  occurs after either of operation  622  or operation  654 , and utilizes image signals obtained either at operation  622  by reading the image sensor  116  using the 4×4 binned read mode or the downsampled image signals generated at operation  654 . In operation  650 , the portion of the image signals from sensing elements that fall within one of the 4×4 binned windows of interest are added to 4×4 binned data corresponding to the respective window of interest, such as in a memory space or a data stream. Thus, a portion of an image is defined in the memory space or data stream. 
     The process then proceeds to operation  670 , where a determination is made as to whether further portions of the image sensor  116  remain that need to be read. If the process is to continue by reading a further portion of the image sensor  116 , the process returns to operation  610 . Otherwise, the process ends. 
     It will be appreciated from the foregoing that the process  600 , when applied to the image sensor  116  and using one or more windows of interest, will result in reading the image sensor using multiple read modes. In one example, application of the process  600  when at least one non-binned window of interest is present will result in receiving a first group of image signals from a first portion of the plurality of sensing elements of the image sensor  116  using at least a first binned read mode such as the 2×2 binned read mode or the 4×4 binned read mode; receiving a second group of image signals from a second portion of the plurality of sensing elements using a non-binned read mode; generating a first image based on at least the first group of image signals and the second group of image signals; and generating a second image based on the second group of image signals. In another example, application of the process  600  when portions outside of windows of interest correspond to a first binned read mode, at least one window of interest corresponds to a second binned read mode, and at least one window of interest corresponds to the non-binned read mode will result in receiving a first group of image signals from a first portion of the plurality of sensing elements of the image sensor  116  using a first binned read mode; receiving a second group of image signals from a second portion of the plurality of sensing elements using a second binned read mode; receiving a third group of image signals from a third portion of the plurality of sensing elements using a non-binned read mode; generating a first image based on at least the first group of image signals, the second group of image signals, and the third group of image signals; generating a second image based on the second group of image signals and the third group of image signals; and generating a third image based on the third group of image signals. 
       FIG. 7  is a functional block diagram showing an apparatus  700 . The apparatus  700  includes an image sensor  710  having a plurality of sensing elements and a control circuit  720 . The control circuit  720  includes a first receiving unit  722  to receive a first group of image signals from a first portion of the plurality of sensing elements using at least a first binned read mode; a second receiving unit  724  to receive a second group of image signals from a second portion of the plurality of sensing elements using a non-binned read mode; a first generating unit  726  to generate a first image based on at least the first group of image signals and the second group of image signals; and a second generating unit  728  to generate a second image based on the second group of image signals. 
     The control circuit  720  may also include a transmitting unit  730 . In some implementations, the transmitting unit  730  is operable to transmit the first image and the second image to a computing device over a single interface by interleaving the first image and the second image. In some implementations, the transmitting unit  730  is operable to transmit the first image via a first interface and to transmit the second image via a second interface. 
     The control circuit  720  may also include a reference image obtaining unit  732  to obtain a reference image. The control circuit  720  may also include a window of interest identifying unit  734  to identify a window of interest. 
     Persons of skill in the art will appreciate that operation of the units and modules of  FIG. 7  can be further understood with reference to corresponding operations in the process  600  of  FIG. 6 , and therefore, previously explained details are not repeated here. 
     It is also apparent for those skilled in the art that the units and modules of  FIG. 7  can be implemented in a device, such as the imaging device  110  of  FIG. 1 , in the form of software, hardware and/or combinations of software and hardware. Units described as separate components may or may not be physically separate. On the contrary, units may be integrated into a single physical component or may be separate physical components. Furthermore, it should be understood that the units, modules, and devices described herein may be implemented in form of software, hardware known or developed in the future, and/or the combination of such software and hardware.