Abstract:
An imaging device has a plurality of predefined regions of interest. The predefined regions of interest may be selected or deselected. Image data from selected regions of interest is transmitted to a host. In some embodiments the regions of interest comprise tiles. A set of selected tiles may be identified by a bit vector. An example application provides a digital camera configured to provide predefined regions of interest. The camera may be configured to permit a host to select or deselect the regions of interest.

Description:
FIELD OF INVENTION 
       [0001]    The invention relates to digital imaging devices, such as cameras, and to apparatus that uses cameras or other imaging devices in applications. The invention has application, for example, in pattern recognition systems and other systems that perform automated analysis of digital images. 
       BACKGROUND 
       [0002]    Image processing systems may have one or more digital cameras that acquire image data and transmit the image data to a processor over suitable data communication channels. For example, a control system for an industrial robot may include a camera that acquires an image showing a part. The control system may process the image to determine the location and orientation of the part. The control system may then cause the robot to perform an action in a manner based on the location and orientation of the part. Similarly, a control system for a wire bonding machine may comprise a camera that acquires an image of a microchip. The control system may process the image to determine a position and orientation of the microchip. The control system may then operate the wire bonding machine to bond wires to specific locations on the chip. These are but two examples of imaging control systems. 
         [0003]    Some cameras are configured in a manner that permits a user to define a region of interest within a digital image. The camera may be operated in such a manner that only data representing the portion of an image within the region of interest is output by the camera. This is useful because, in some applications only a portion of an image is required for image processing. Sending a portion of an image may permit the acquisition rate to be increased in some embodiments. Sending a portion of an image may reduce the amount of data being sent over a bus or other data communication channel in some embodiments. This, in turn, can allow more cameras to share the same data communication channel. 
         [0004]    It is typically cumbersome to define a region of interest. The position and boundary of the region of interest must be specified. At a processor it can be necessary to allocate memory to provide a buffer of sufficient size to receive the image data. An application that processes data from such a camera typically requires significant custom programming to properly define a region of interest and to interpret data provided by the camera. 
         [0005]    The inventors have recognized a need for efficient cost effective methods and apparatus in which a digital imaging device is configurable to send data for only one or more selected regions of interest. The inventors have recognized a particular need for such methods and apparatus that can be applied in industrial settings such as automated manufacturing. 
       SUMMARY OF THE INVENTION 
       [0006]    This invention provides image capture devices (of which cameras are one example) and methods and apparatus for configuring an image capture device to output regions of interest from within a full image. One aspect of the invention provides a camera which has a number of pre-defined regions of interest. The regions of interest are smaller than a full image. A controller in the camera is configured to receive instructions in a compact syntax for identifying selected ones of the regions of interest and subsequently cause the camera to acquire and transmit image data for the selected regions of interest. Image data for regions not included in any regions of interest is not transmitted in some embodiments. 
         [0007]    In some embodiments, an array of pixels of a digital imaging device is logically divided into predefined regions, which may be called tiles. A controller of the digital imaging device is configurable to select or deselect individual ones of the tiles. An identifier may be assigned to each tile. The identifier may be a number. A desired subset of selected tiles may be specified, for example, by a bit vector in which each bit in the vector maps to a corresponding tile. Enabling a bit in the bit vector will cause the tile corresponding to the enabled bit to be selected. 
         [0008]    In some embodiments, the tiles make up a static, regularly-spaced array. Having tiles that are not static or are irregularly spaced does not make the invention impossible to implement, only more complicated. 
         [0009]    An imaging device and host system may be connected by a suitable data bus. In some embodiments, the imaging device and/or host system are configured to perform bandwidth negotiation prior to transmitting image data for selected tiles. The amount of bandwidth required depends on, the number of pixels transmitted, and the pixel format and desired frame rate of the digital imaging device. 
         [0010]    Where the pixel format and frame rate of the digital imaging device is constant, the amount of bandwidth required will directly correlate with the number of pixels being transmitted, which depends, in turn, on the number of selected tiles. 
         [0011]    In one embodiment, the amount of bandwidth is renegotiated when the number of selected tiles is modified. This embodiment ensures optimal bandwidth usage. In one embodiment, the amount of bandwidth is renegotiated when the number of selected tiles is increased or decreased by more than a threshold number of selected tiles. Renegotiating bandwidth may be performed more intermittently in order to conserve computing resources. 
         [0012]    Another embodiment, involves negotiating a maximum expected bandwidth determined by the maximum expected number of selected tiles. In this embodiment, the output image data may be padded, for example, with 0&#39;s when there is too much bandwidth, and may be truncated when there is not enough bandwidth. The number of active tiles in the subset of active tiles can be compared to the maximum expected number of tiles used to configure the bandwidth to insure that the allocated bandwidth will not be exceeded in normal operation. 
         [0013]    Another aspect of the invention provides apparatus and methods wherein information identifying the subset of active tiles is embedded into output image data. While this is not mandatory, it is advantageous to facilitate ease of use of the image data. 
         [0014]    Further aspects of the invention and features of embodiments of the invention are set out below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The accompanying drawings illustrate non-limiting embodiments of the invention. 
           [0016]      FIG. 1  is a flow chart illustrating a method according to an example embodiment of the invention. 
           [0017]      FIG. 2  is a schematic diagram of a system according to an example embodiment of the invention; an imager of a digital imaging device illustrating associations between pixels in the imager and an 8×8 regular array of tiles. 
           [0018]      FIG. 2A  is a schematic illustration of an imaging device according to an embodiment of the invention. 
           [0019]      FIG. 2B  illustrates an example association between non-overlapping tiles and pixels of an imaging array. 
           [0020]      FIGS. 3A ,  3 B and  3 C respectively illustrate image-aligned, tile-aligned and tile-interleaved data formats. 
           [0021]      FIG. 4  is a schematic illustration depicting a wire boding machine according to an example implementation of the invention. 
           [0022]      FIG. 5  is a block diagram illustrating a system according to another example implementation of the invention. 
       
    
    
     DESCRIPTION 
       [0023]    Throughout the following description, specific details are set forth in order to provide a more thorough understanding of the invention. However, the invention may be practiced without these particulars. In other instances, well known elements have not been shown or described in detail to avoid unnecessarily obscuring the invention. Accordingly, the specification and drawings are to be regarded in an illustrative, rather than a restrictive, sense. 
         [0024]      FIG. 1  is a flow chart illustrating a method  10 .  FIG. 2  illustrates schematically a system  50  that may be used in the practice of method  10 . Method  10  is performed in a system, such as system  50  which includes an imaging device  12  and a host  14  coupled by a data link  16 . Imaging device  12  generates image data. The image data comprises values associated with pixels in a sensing array. 
         [0025]    Imaging device  12  may comprise a charge-coupled device (CCD), active pixel sensor (APS), complementary metal oxide semiconductor (CMOS) sensor or other imaging sensor. Imaging device  12  does not necessarily sense visible light but could sense other things such as infrared light, ultraviolet light, or other electromagnetic radiation outside of the visible part of the spectrum; temperatures, vibration levels, or other measurable physical quantities; chemical concentrations; or the like. Imaging device  12  may comprise another source of image data such as a data processor running a simulation that produces image data. Imaging device  12  may optionally comprise a data processor, image processor or the like that processes raw image data from a suitable sensing array into the image data to be sent to host  14 . 
         [0026]    In some embodiments, imaging device  12  is capable of generating a large volume of image data. For example, in some embodiments, imaging device  12  is capable of generating values for 1 million or more pixels, in some cases, 6 million or more pixels. Each pixel value may be represented by several bits of digital data. For example, in some imaging devices, each pixel value is represented by 8 to 24 bits of digital data. In some cases, a new set of image data is created periodically at a frame rate which may, for example, be in excess of 1 Hz and in some cases is 30 Hz, 60 Hz, 200 Hz, or more. 
         [0027]    Data link  16  may comprise, for example, a serial bus such as an IEEE 1394 (also known as Firewire™) interface, Cameralink™, Ethernet (GigE), USB, another wired data communication interface, an optical data channel, a wireless data channel or the like. In some cases, data link  16  is a bottleneck that limits the performance of system  50 . This is especially the case where latency is an issue. For example, consider the case where system  50  comprises a control system for a robot such as a manipulator or the like and host  14  controls actuators that make parts of the robot move in response to image data. In such as system image data from imaging device  12  may be used to provide feedback to motion control algorithms. Delays in transmitting the image data from imaging device  12  to host  14  can limit in the overall performance of the robot. 
         [0028]    Host  14  may comprise a data processor, an image processor, which may be implemented in software, hardware, or a combination thereof, a programmed computer such as a personal computer or workstation, an embedded controller for an apparatus or system or a component of an apparatus or system, a collection of programmable controllers or data processors, or the like. In some embodiments, an embedded controller, which may constitute all or part of host  14  or another data processor and one or more imaging devices  12  are tightly coupled. This might be the case, for example where the embedded processor and imaging device(s)  12  are components of a ‘smart camera’. 
         [0029]    Block  20  of method  10  comprises providing one or more predefined regions of interest  15  in imaging device  12 . Each of the predefined regions of interest includes a subset of pixels in an array  13  of pixels  13 A of imaging device  12  (see  FIG. 2A ). Where there are two or more predefined regions of interest, it is not mandatory that the regions of interest be equal in size, of the same shapes and/or dimensions, or non-overlapping. 
         [0030]    It is convenient to provide predefined regions of interest that are regularly-spaced, do not overlap, and are of the same sizes and shapes. In the embodiment illustrated in  FIG. 2B , the predefined regions of interest specified in block  20  of method  10  (see  FIG. 1 ) comprise tiles  15 A. Tiles  15 A comprise rectangular groups of pixels  13 A that are non-overlapping and regularly-spaced. In the illustrated embodiment, the entire area of array  13  is covered with non-overlapping tiles  15 A. In the illustrated embodiment, each tile  15 A contains the same number of pixels. In the illustrated embodiment, each tile  15 A has the same shape and dimensions. It is not mandatory that tiles  15 A have these attributes in all embodiments. 
         [0031]    In some embodiments, tiles  15 A have widths that are an even multiple of 8. In some embodiments there are between 25 and 256 predefined regions of interest. For example, it can be convenient to divide the image data produced by a camera into an array of tiles that is 8×8 or 16×16. Such embodiments have enough tiles that are large enough that, for many applications, image data for only a few tiles will be required and yet the image data for a few tiles is much smaller than the image data for the entire area of the imaging array. Arrays of tiles having other dimensions such as 7×7 or 10×12 are also possible. 
         [0032]    The allocation of pixels  13 A to tiles  15 A does not need to be reflected in the physical structure of imaging array  13 . The pre-allocation of pixels  13 A to tiles  15 A is a logical relationship. As discussed below, that logical relationship may be embodied in any suitable manner including one or a combination of:
       circuitry;   a data record, data structure, data store or the like;   configurable circuitry (such as a field-programmable gate array or the like);   the configuration of array  13  (an array  13  may be constructed so that data from predefined regions of interest can be selectively read from the array); etc.       
 
         [0037]    In preferred embodiments the predefined regions of interest:
       are defined statically;   are fixed; and/or   do not require initialization.       
 
         [0041]    In block  22  imaging device  12  receives region selection information identifying one or more of the predefined regions of interest provided in block  20 . The region selection information preferably identifies selected regions by way of a compact identifier. The compact identifier may, for example, comprise a number corresponding to the selected region. In one embodiment, the compact identifier for each selected region comprises a logic flag, which may comprise one-bit, for example a position in a bit vector. Enabling the flag selects a corresponding one of the regions. Disabling the flag deselects the corresponding region. 
         [0042]    The region selection information may be received at imaging device  12  in various manners. For example:
       region selection information may be entered by way of a user interface  17  of imaging device  12 ;   host  14  may transmit region selection information over data link  16  in a message addressed to or otherwise delivered to imaging device  12 ;   host  14  may store region selection information in a memory location that is in or accessible to imaging device  12 ; or   the like.
 
The region selection information identifies one or more of the previously-defined regions of interest and, in preferred embodiments, does not contain sufficient information (position, size, shape etc.) to define the regions of interest.
       
 
         [0047]    In block  24 , imaging device  12  maintains a list or other record  18  of selected tiles  13 B. List  18  is maintained within a selected tile register  19  of imaging device  12 . As described below, imaging device  12  uses the information about what tiles are selected to assemble image data from the selected tiles (or other regions of interest) for transmission to host  14 . 
         [0048]    In block  26  method  10  allocates bandwidth for the delivery of image data from imaging device  12  to host  14  over data communication path  16 . Block  26  is optional, especially in cases where:
       sufficient bandwidth is pre-allocated,   data communication path  16  is dedicated solely to communication between host  14  and imaging device  12 ,   there is more than sufficient bandwidth for imaging device  12  and any other devices that share data communication path  16 .
 
Allocation of bandwidth may be based upon the number of selected tiles  15 A or, more generally, on a number of pixels in selected regions of interest  15  (there is a difference when different regions of interest include different numbers of pixels). In this way sufficient bandwidth for the transmission of image data for the selected tiles  15 A is made available while allowing any surplus bandwidth to be allocated for other purposes.
       
 
         [0052]    In some embodiments, block  26  comprises allocating bandwidth sufficient for the image data for an expected maximum number of selected tiles  13 B. This approach can be advantageous in cases where reducing the overhead of re-allocating bandwidth each time the number of selected tiles  13 B changes is more important than minimizing the bandwidth allocated to the transmission of image data from imaging device  12  to host  14 . 
         [0053]    The mechanism for reserving or allocating bandwidth for image data, if there is such a mechanism, may be provided for in the protocol governing the operation data link  16 . Various mechanisms for reserving bandwidth are available commercially and/or known to those of ordinary skill in the art of designing data communication links. 
         [0054]    In block  28 , imaging device  12  acquires image data. Block  28  may involve opening mechanical or electronic shutters of a camera, acquiring a video frame or the like. Block  28  need not occur at the location in method  10  indicated in  FIG. 1 . Block  28  may cycle continuously or occur at any time prior to block  29 . In some embodiments it is important that image data be recent. In such embodiments, block  28  may occur immediately prior to block  29 . 
         [0055]    In block  29  imaging device  12  reads out the image data from imaging array  13 . In some embodiments, performance is improved by not reading out image data from at least some pixels that are outside of the selected tile(s)  13 B. Block  29  may comprise storing the image data in a data buffer or other memory in or accessible to imaging device  12 . 
         [0056]    In block  30 , imaging device  12  transmits image data from the selected tile(s) to host  14  by way of data communication path  16 . In some applications, blocks  29  and  30  may be performed simultaneously so that image data that has been read out of imaging array  13  earlier is transmitted to host  14  while other image data is still being read out of imaging array  13 . 
         [0057]    Image data may be transmitted to host  14  in any suitable format. Some example formats are:
       image-aligned formats;   tile-aligned formats; and,   tile-interleaved formats.
 
In an image-aligned format, data standing for the pixels in the entire image or an entire part of the image is transmitted, only the pixels in selected tiles contain actual values. Data in the image-aligned format corresponding to pixels outside of the selected tiles is set to a placeholder value (for example, zero). In some embodiments the protocol by which data is transmitted over data communication path  16  involves compression. In such embodiments, large contiguous areas within the image data in which the image data is set to the placeholder value can be transmitted very efficiently.
       
 
         [0061]      FIG. 3A  is an example of a data structure  40  holding image data in an image-aligned format. Data structure  40  has data corresponding to a number of selected regions (corresponding to corners of the imaging array in the illustrated example) and placeholder data in other regions. In  FIG. 3A  the placeholder data is indicated by “0”s and the image data is indicated by “X”s. The “X”s represent varying image data.  FIG. 3A  is schematic. In a typical implementation data structure  40  would comprise many more values than are illustrated in  FIG. 3A . For example, data structure  40  may have values corresponding to a few hundred, a few thousand or more pixels in each dimension. 
         [0062]    In a tile-aligned format, the output image data transmitted to host  14  is made up substantially entirely of data from selected tiles. Data corresponding to non-regions selected regions of the image is not transmitted. Data for different tiles is separated (e.g. the data for different tiles may be sent sequentially). This can introduce latency in cases where the transmission of data for one tile is not commenced until the readout of data for a previous tile is completed and the data for the previous tile has been transmitted. 
         [0063]      FIG. 3B  is an example of a data structure  43  holding image data in an tile-aligned format. Data structure  43  has sections  44 A through  44 D each containing image data corresponding to one selected region of interest (regions of interest  15 - 1 ,  15 - 2 ,  15 - 3  and  15 - 4  of imaging array  13  in the illustrated example). 
         [0064]    In a tile-interleaved format, data is transmitted in row-order but only data from selected tiles is included. Where a range of rows includes pixels belonging to two or more different selected tiles, data from the selected tiles is interleaved. A tile-interleaved format has the advantage of low latency at the cost of somewhat increased complexity in processing the data. 
         [0065]      FIG. 3C  is an example of a data structure  45  holding image data in a tile-interleaved format. In data structure  45 , data is arranged in the same order as it is read out of imaging array  13 . This results in rows of any regions of interest that have pixels from the same row of imaging array  13  being interleaved. For example, regions of interest  15 - 1  and  15 - 2  are on the same rows of imaging array  13  and so the rows of image data from regions of interest  15 - 1  and  15 - 2  are interleaved in data structure  45 . 
         [0066]    In some embodiments, a variable-sized buffer is allocated at host  14  to receive the image data. The size of the buffer may be allocated to hold the expected image data. In some embodiments, the buffer is allocated by
       determining the number of selected tiles in each row;   determining the maximum number of selected tiles in any row of tiles;   determining the number of rows containing any selected tiles;   allocating a buffer having a width sufficient to receive the maximum number of selected tiles times the number of columns in each active tile and a height sufficient to receive the number of rows containing selected tiles times the number of rows in each tile.
 
Incoming image data can then be directed into the buffer. This may be performed by direct memory access (DMA) or any other suitable technology.
       
 
         [0071]    In block  32  host  14  processes the image data to provide some result, such as control signals for apparatus controlled by host  14 , or the like. Loops  34 A and/or  34 B can be repeated to transmit fresh image data from imaging device  12  to host  14  at a suitable frame rate. 
       EXAMPLE 
       [0072]      FIG. 4  shows a wire-bonding machine  80  according to an example embodiment of the invention. Machine  80  comprises a stage  82  that is movable in X and Y directions and can also be rotated. A VLSI chip  83  is mounted on stage  82  and is imaged by a camera  85 . A wire-bonding tip  86  that is movable in the Z direction by an actuator  88  controlled by controller  84  is supported over chip  83 . Controller  84  controls X-Y motion and rotation of stage  82  in response to image data received from camera  85  over bus  87  by suitably controlling actuators  89 . 
         [0073]    When chip  83  is first placed on stage  82  the precise location and orientation of chip  82  is not known. Controller  84  first must ascertain the position and orientation of chip  82  so that it can accurately position tip  86  over specific features on chip  83 . For this purpose, controller  84  obtains from camera  85  an image of chip  83 . It is not necessary to obtain image data for the entire chip  83  since the position and orientation of chip  82  can be determined by observing registration marks  91  that are present on chip  82  (for example on corners of chip  82 , as shown). Controller  84  sends to camera  85  region select information selecting only certain predefined regions of the image covering areas where registration marks  91  corners of chip  82  are expected to be seen (e.g. regions of interest that include image data for the corners of chip  82 ). 
         [0074]    Camera  85  acquires an image and stores image data from the selected regions of interest in a buffer. As soon as there is sufficient image data in the buffer, camera  85  begins transmitting the image data to controller  84 . Only image data for the selected predefined regions of interest is transmitted to controller  84 . Advantageously, the image data is transmitted in an image-aligned or tile-interleaved format so that data transmission can begin before image data for any region of interest has been read out of the imaging array of camera  85 . 
         [0075]    Controller  84  receives the image data, if necessary, identifies image data corresponding to individual regions of interest, and processes the image data using any suitable image-processing techniques to identify and measure locations of registration features  91  in the image data. From the locations of the registration features, controller  84  computes the position and orientation of chip  82 . The position and orientation data can then be used to determine a sequence of motions of actuators  89  to bring tip  85  into alignment over various features on chip  82  and to actuate actuator  88  and other systems to perform wire bonding or other actions on chip  82 . For example, wires may be bonded to connect bonding pads on chip  82  to bonding pads on a chip package (not shown). 
       EXAMPLE 
       [0076]      FIG. 5  shows apparatus  90  according to an example embodiment of the invention. Apparatus  90  comprises an imaging device  92 , for example a digital camera, connected to a host  94  by a data connection  93 . Imaging device  92  has an imaging array  95  having image data output lines  96 . A data selector  97  receives data from image output lines  96  and selects data corresponding to selected regions of interest. Data selector  97  determines which predetermined regions of interest have been selected by reading selected region data such as a bit vector  98  in a memory  99 . The selected region data identifies selected regions. In the illustrated embodiment, one bit of bit vector  98  corresponds to each predefined region available for selection. The bit vector serves as a set of flags. A region is selected if the corresponding bit of bit vector  98  is enabled and is not selected if the corresponding bit of bit vector  98  is not selected. 
         [0077]    Imaging device  92  has an optional data formatting stage  100  that, for example, collects image data for individual selected regions so that the image data can be inserted into a buffer in a tile-aligned format or inserts placeholder values where the image data is desired to be provided in an image-aligned format. A buffer  102  receives image data (as formatted by formatting stage  100 ). An interface  104  transmits the image data from buffer  102  across data connection  93  to host  94 . At host  94  the received image data is taken in at a suitable interface  105 , stored in a buffer  106  and is available to a data processor  108  that works with the image data under the control of instructions provided by software  109 . 
         [0078]    In any of the embodiments described herein, information identifying the selected region(s) of interest may be transmitted with image data being sent by the imaging device to the host. For example, the selected regions of interest may be embedded in a header or trailer attached to the image data. In such embodiments, the close association of the information identifying the selected region(s) of interest and the image data may facilitate later processing or interpretation of the image data. Information identifying the selected region(s) of interest may be associated with or linked to the corresponding image data in other ways such as by the provision of a pointer, data structure or the like that indicates what region(s) of interest were selected for a given image data. 
         [0079]    Data selector  97  and data formatting stage  102  may be provided by any suitable technology including, without limitation one or more of:
       logic circuits;   configurable logic, such as a field-programmable gate array (FPGA) configured to perform the functions defined above; and   a suitably programmed data processor such as a microprocessor, image processor, graphics processor, digital signal processor or the like.       
 
         [0083]    In the illustrated embodiment, host  94  can control the content of memory  99  either directly or indirectly. By storing different bit vectors  98  in memory  99 , host  94  can control which regions of interest are selected at imaging device  92 . This may be done in response to software instructions being executed on data processor  108  of host  94 . Thus, host  94  can direct imaging device  92  to provide image data for a first group of one or more regions of interest to enable host  94  to perform a first task (such as determining the orientation and location of a chip by visualizing reference marks on the chip, for example) and to subsequently shift to provide image data for a second group of one or more regions of interest to enable host  94  to perform a second task (such as positioning a wire bonding tip  85  over a specific feature on the chip, for example). 
         [0084]    It can be appreciated that selected embodiments of the invention can be applied to advantage in various situations. For example, suitable embodiments may be applied in situations where one or more of the following conditions exist (although the invention is by no way limited to situations in which these conditions exist):
       Available bandwidth for carrying image data to a host is limited—data transmission can be reduced by transmitting data for required regions of interest only.   It is desired to operate an imaging array at an increased frame rate for better temporal resolution or reduced latency—some imaging devices can be operated at greater frame rates where the number of rows of image data being read out are reduced. In some embodiments, the digital imaging device may be configured to operate at an increased frame rate or rates when selected regions of interest occupy a reduced number of rows.   It is desired to reduce latency—which can be done by selecting and transmitting only image data from regions of interest.   It is desired to change which regions of interest are selected frequently or with low overhead.   It is desired to provide an imaging device in which regions of interest may be defined easily and with low overhead.   It is desired to take advantage of the increased performance of some sensors, such as certain CMOS sensors, attainable by reducing the number of columns that are read.       
 
         [0091]    From the foregoing description and the accompanying drawings it can be seen that the invention may be embodied, without limitation, in any of:
       an imaging device such as a camera;   a system which includes an imaging device; and,   a method for configuring, selecting and/or using regions of interest in image data.       
 
         [0095]    Where a component (e.g. a software module, processor, assembly, device, circuit, etc.) is referred to above, unless otherwise indicated, reference to that component (including a reference to a “means”) should be interpreted as including as equivalents of that component any component which performs the function of the described component (i.e., that is functionally equivalent), including components which are not structurally equivalent to the disclosed structure which performs the function in the illustrated exemplary embodiments of the invention. 
         [0096]    As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. For example:
       It is not mandatory that predefined regions of interest are rectangular. Regions of interest could have other regular shapes such as circular or could have more complicated bound shapes designed for specific applications;   It is not mandatory that image data corresponding to every pixel of an imaging array be included in a predefined region of interest. In some embodiments, regions of interest are predefined only for some parts of an image.   It is not mandatory that predefined regions of interest do not overlap.
 
Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.