Abstract:
An image analysis and enhancement system is provided with an image processor, imaging metrics, an image storage depository, and a reconfigurable sensor device that can be present at the same location. A remote reconfigurable sensor device is connected to the image processor via a communication link. Both the reconfigurable sensor device and the remote reconfigurable sensor device are equipped with selectable optical elements and imaging elements that are selected in a desired combination and orientation to capture desired image frames from a target scene or object. The selectable optical and imaging elements are provided with actuating devices to move and translate the selected optical and imaging elements into a desired orientation with one another, so that a desired imaging technique can be employed to obtain an enhanced image. The system is applicable to industrial, medical and military use.

Description:
[0001]    This is a divisional of non-provisional application Ser. No. 11/225,405 for “IMAGE ANALYSIS AND ENHANCEMENT SYSTEM” filed on Sep. 13, 2005. 
     
    
     DEDICATORY CLAUSE 
       [0002]    The invention described herein may be manufactured, used and licensed by or for the U.S. Government for governmental purposes without payment of any royalties thereon. 
       BACKGROUND OF THE INVENTION 
       [0003]    1. Field of the Invention 
         [0004]    The present invention pertains to the field of imaging. More particularly, the present invention relates to a system of imaging that utilizes a plurality of image collection hardware elements that can be selectively employed to give a desired image configuration for a desired imaging technique. 
         [0005]    2. Discussion of the Background 
         [0006]    The prior art demonstrates a number of techniques used for image processing. These techniques involve configuring and then reconfiguring an image to achieve an improved image, i.e., an image reconfiguration. 
         [0007]    For example, it is well established that contrast is reduced when a scene is viewed through a medium with suspended particles in it, but contrast can be enhanced by viewing the scene through two orthogonal polarizations, then taking the difference between the two polarized scenes. Taking the difference between the two polarizations has the effect of reducing the scattering, thus enhancing the contrast. The medium could be the earth&#39;s atmosphere filled with dust, or aerosols or a piece of biological tissue viewed through a microscope. U.S. Pat. No. 5,975,702 to Pugh, Jr. et al. that issued Nov. 2, 1999 and which is herein incorporated by reference demonstrates this method of polarization differencing. 
         [0008]    The ability to collect a large number of narrow hyperspectral images of the same scenes allows one to then select the best set of a smaller number of bands that give the best signal to noise ratio, and the bands need not may be contiguous. 
         [0009]    A well established art in the field of hyperspectral imaging has been made possible by the voltage controlled acousto-optical tunable filter. The imagery that can be collected through such tunable filters can be quite varied—from topographical scenes to the imaging of biological specimens. 
         [0010]    Acousto-optic tunable filters (AOTF&#39;s) are taught in U.S. Pat. No. 4,720,177, U.S. Pat. No. 4,685,772 and U.S. Pat. No. 5,329,397 to Chang which issued on Jan. 19, 1988, Aug. 11, 1987, and Jul. 12, 1994, respectively, the teachings of which are herein incorporated by reference. In U.S. Pat. No. 5,576,880 that issued Nov. 19, 1996, and which is herein incorporated by reference as well, Chang teaches an acoustic-optic modulator. AOTF&#39;s are used in a variety of imaging and display systems. An example of a display system utilizing an AOTF is U.S. Pat. No. 5,410,371 to Lambert which issued on Apr. 25, 1995, the teachings of which are herein incorporated by reference. 
         [0011]    Another imaging technique has been to obtain an in-focus image and an out-of-focus image and then subtract the out-of-focus image from the in-focus image to obtain an enhanced image by removing the lower frequency components. This concept is disclosed in U.S. Pat. No. 6,433,325 to Trigg which issued on Aug. 13, 2002 the teachings of which are herein incorporated by reference.  FIG. 1  demonstrates an embodiment from the Trigg patent in which a microscope body  18  having an optically aligned lens  14  and focal array  16  is operably connected to a ball screw assembly  20  that is driven by a motor  22  and controlled by a computer  24 . A sample  12  resting on a sample stage  10  can be brought in and out of focus by the operation of the ball screw assembly. 
         [0012]    The highest frequency component that can be captured in a focal plane array is limited by the detector pitch, or the spacing between the centers of the pixel elements. Under the Nyquist criteria, the highest frequency that a band-limited spectra can contain to be fully recoverable is one half the sampling rate, which in the case of the staring focal plane array is one half of the detector pitch. 
         [0013]    Since infrared scenes typically contain frequencies higher than one half the sampling rate of the focal plane array, the result is aliasing, or the overlap of adjacent spectra leading to distortion of the sampled signals and the loss of information in the reconstruction process. 
         [0014]    The reduction in distortion from aliasing can be achieved by a process of microscanning that shifts the image plane a fraction of the detector pitch in two coordinates over the focal plane array. This technique allows the capture of higher frequency components in an image that would otherwise be lost in distortion. The technique is presented in U.S. Pat. No. 5,774,179 to Chevrette et al. that issued on Jun. 30, 1998, the teachings of which are hereby incorporated by reference. 
         [0015]    To establish some measure of quality of an image, a conceptual ruler or metric is needed. One commonly used metric in image analysis that has been used is the peak signal to noise ratio (PSNR). 
         [0016]    If one image is defined as the reference image, then the degree of dissimilarity with a comparison image is given in terms of a distance measure or error. The most obvious measure of distance between two images is obtained by comparing them on a pixel-by-pixel basis and taking the difference between the pixel values (pixel difference metrics). For example, if a sensor device collects an image and it is compressed for transmission, and then decompressed, the decompressed image will differ from the original image by the errors or artifacts introduced by the compression-decompression process. 
         [0017]    The variety of image similarity metrics previously used in imaging technology, has included spectral angle mapping, Euclidian distance and others. These metrics have ambiguities, and efforts have been made to improve them with something called a “spectral similarity scale”. A method for determining spectral similarity is disclosed in U.S. Pat. No. 6,763,136 that issued to Sweet on Jul. 13, 2004 which is hereby incorporated by reference. 
         [0018]    In that the type of image that is desired and the circumstances and conditions under which an image is obtained can vary greatly, a need is seen for an image analysis and enhancement system that has the ability to utilize a multiplicity of imaging techniques positioned at local and/or remote locations. 
       SUMMARY OF THE INVENTION 
       [0019]    Accordingly, one object of the present invention is to provide an image analysis and enhancement system that is able to selectively employ a plurality of optical element and imaging elements for obtaining desired imaging frames. 
         [0020]    Another object of the present invention is to provide a centralized or local image enhancement center that is equipped to process images utilizing a variety of techniques. 
         [0021]    Another object of the present invention is to allow for image processing of images obtained from different locations at a central image enhancement center. 
         [0022]    Still another object of the present invention is to realize new imaging techniques made possible by the interchangeability of respective optical and imaging elements utilized by the present invention. 
         [0023]    These and other valuable objects are achieved by an image analysis and enhancement system having an on-location-imaging center having an image processor that interfaces with imaging metrics. The image processor is provided with software for implementing a variety of imaging techniques. An image depository is connected to the image processor for storing collected image frames. Control means including controlling software and a keyboard input means are connected to the image processor. A display for viewing the processed and enhanced images is connected to the image processor. A reconfigurable sensor system or device is connected to the image processor with the reconfigurable sensor device having a plurality of optical and image collecting elements which can be selectively arranged for purposes of obtaining an image to be processed by a predetermined imaging technique. 
         [0024]    At least one remote reconfigurable system or device may be connected to the image processor by means of a communication link. The remote reconfigurable system is likewise provided with a plurality of optical and imaging elements that can be selectively arranged for purposes of obtaining an image to be processed by a predetermined imaging technique. 
         [0025]    The remote reconfigurable sensor device can be placed at a remote geographical location on a platform, vehicle or aircraft at the remote location. Accordingly, the remote reconfigurable sensor device can interface with a local command imaging center that is many miles away. The remote and local reconfigurable sensor devices can be used for various applications including military, industrial and medical applications. 
         [0026]    The hardware included in the reconfigurable sensor devices includes at least one optical member or lens, means for polarizing an image at more than one angular orientation, a hyperspectral filter, and a focal plane array. Means are provided to change the pitch of the optical member, and means are provided to translate and move the hyperspectral filter, polarizing means and focal plane into desired imaging orientations. Still further, means are provided so the hyperspectral filter, polarizing means and focal plane array can be selectively utilized. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings described below. 
           [0028]      FIG. 1  is a schematic illustration of a prior art device used for image enhancement. 
           [0029]      FIG. 2  is a schematic block diagram of the image analysis and enhancement system according to the present invention. 
           [0030]      FIG. 3  is a cutaway side-view illustration of a reconfigurable sensor device according to one embodiment of the present invention. 
           [0031]      FIG. 4  is a top view of a lens provided with optical actuators according to the embodiment of the present invention shown in  FIG. 3 . 
           [0032]      FIG. 5  is a schematic illustration of an optical actuator demonstrated in  FIGS. 3 and 4 . 
           [0033]      FIG. 6  is a schematic illustration of a translatable actuating element according to the embodiment of the present invention shown in  FIG. 3 . 
           [0034]      FIG. 7  is a schematic illustration of another embodiment of an optical sensor system that is adaptable for utilization with a plurality of sensor enhancement techniques. 
           [0035]      FIG. 8  is a block diagram that illustrates an image enhancement technique that can be utilized by the present invention. 
           [0036]      FIG. 9  is a block diagram that illustrates a second image enhancement technique that can be utilized by the present invention. 
           [0037]      FIG. 10  is a block diagram that illustrates a third image enhancement technique that can be utilized by the present invention. 
           [0038]      FIG. 11  is a block diagram that illustrates some of the imaging step capabilities that can be utilized by the present invention. 
           [0039]      FIG. 12  is a block diagram that illustrates additional imaging step capabilities that can be utilized by the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0040]    Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, and, more particularly to  FIG. 2  thereof, an image analysis and enhancement center  50  of an image enhancement and analysis system  40  is provided with an image processor or central processing unit  52 . Imaging metrics  54  connect and interface with the image processor  52 . The imaging metrics  54  may include any number of software-based metrics utilized for imaging. An image depository or image storage or memory unit  56  is connected and interfaces with the image processor  50 . A reconfigurable sensor device or system  58 , which may be comprised of many components, is used to obtain various configurations of images of a target object for processing by the image processor  52 . 
         [0041]    Imaging can be initiated and controlled by a controller  60  which can include a keyboard for interfacing with the image processor  52 . A display  62  is connected to the image processor  52 . The display can be one of various varieties of computer-type monitors. A printer device (not shown) can be connected to the image processor as well. 
         [0042]    The image processor  52 , imaging metrics  54 , image depository  56  and reconfigurable sensor device  58 , as well as control  60  and display  62  are all located in an image analysis and enhancement center  50 . The respective elements of the image analysis and enhancement center can be accommodated in a small room. 
         [0043]    A remote reconfigurable sensor device  64  positioned at a remote location  66  is connected to the image processor  52  through a communication link  68 . The communication link can be a fiber optic link, a satellite feed, or other appropriate link for channeling image data from the remote reconfigurable sensor device  64  to the image processor  52 . This remote reconfigurable sensor device  64  may be located hundreds or even thousands of miles from the image processor  52 . 
         [0044]    The images collected by the reconfigurable sensors,  58 ,  64  are delivered to the signal processor for image processing. The software provided for the signal processor can include such processing tools as segmentation, edge detection, image restoration, image fusion, image enhancement, image compression, and image comparison, and image comparison with images from storage. 
         [0045]    Tools derived from multi-resolution theory allow the decomposition of an image into different resolution levels, then operations on the selected resolution level are followed by reconstruction. 
         [0046]    The software employed by the image processor can include software for realizing Fourier and wavelet transformations of the image data. Examples of imaging that utilize wavelet transformation are disclosed in U.S. Pat. No. 6,094,050 that issued to Zaroubi et al. on Jul. 25, 2000 and in U.S. Pat. No. 6,751,363 that issued to Natsev at al. on Jun. 15, 2004 both of which are herein incorporated by reference. 
         [0047]    The Fourier transform can characterize the resolution of an image only on the dimension of wavelength. On the other hand, the wavelet transform can characterize resolution in both the frequency and spatial dimension and provides many tools and possibilities for utilization by the image processor  52 . 
         [0048]    Wavelets extend the power of the Fourier transform and its inverse as a tool for analysis and synthesis of signals. The Fourier transform has only two building blocks (“basis functions”) for these processes: sines and cosines. Since these functions are continuous from −infinity to +infinity, the only kind of signals that the Fourier transform can deal with is PERIODIC signals. Wavelets on the other hand are designed for processes of analysis and synthesis of TRANSIENT signals or signals with DISCONTINUITIES. 
         [0049]    In contrast with the Fourier transform and its inverse, wavelets have a practically unlimited number of building blocks (or “basis functions”). This has provided a gold mine for mathematicians, physicists and engineers in formulating new wavelet tools for signal processing functions. The great power of wavelets in two-dimensional image processing is the ability to DETECT LOCALIZED EDGES in the image. One specific application that has attracted widespread attention is the conversion of 29 million inked fingerprint card files in the FBI Criminal Justice Information Services to electronic form for quick retrieval and search of the database by automated fingerprint identification systems. This conversion technique which allows for quick retrieval by automated means is accomplished by means of wavelets. 
         [0050]    With reference to  FIG. 3 , a microscope-type reconfigurable image-enhancement sensor device  90  is provided with an optical lens or member  70  that is supported on an actuator frame  75  provided with optical actuators  72 . The actuator frame  75  extends from a lower support member  99  of a support body  92  that is supported by support member  98 . 
         [0051]    A support arm  94  extends from the lower support member  99 . A support body elevation-control mechanism  85  can be employed to raise and lower the support body so that the optical member  70  is positioned at a desired focal position. 
         [0052]    The support arm  94  is provided with a plurality of translatable optical element actuators  96 A,  96 B,  96 C.  96 D ( FIG. 6 ) which are further discussed below. A hyperspectral filter  76 , polarizer  80 , and focal plane array  82 , and auxiliary detector  84  are optically aligned on an optical axis  74  with optical member  70 . (The detector  84  is utilized to capture a visual image when the focal plane array is not utilized). The optical axis  74  extends to a target sample  100  that is positioned on a support member  102 . 
         [0053]    In  FIG. 4 , a top view shows that the optical member  70  is supported by a plurality of actuators  72 A,  72 B,  72 C, and  72 D that can be utilized to change the pitch of the optical member in two coordinates. Each actuator  72  is provided with an actuating finger  73  ( FIG. 5 ) that can be moved backwards and forwards as desired by piezo-electric or other equivalent means. Since each finger  73  is at an angle with lens  70 , this allows incremental lateral and upward and downward movement of the lens so as to enhance microscanning capability. 
         [0054]    The support arm  94  is used to support hyperspectral filter  76 , polarizer  80 , polarizer  81 , and focal plane array  82 . On the support arm  94 , actuator  96 A is connected to hyperspectral filter  76 , actuator  96 B is connected to polarizer  81 , actuator  96 C is connected to polarizer  80  and actuator  96 D is connected to focal plane array  82 . These actuators allow filter  76 , polarizers  80  and  81 , and focal plane array  82  to be moved in incremental distances in both the lateral direction and vertical directions. Further, the actuators  96 A,  96 B,  96 C,  96 D allow the filter  76 , polarizers  80  and  81 , and focal plane array  82  to be rotated from a position in the focal section  95  of the support body to a storage section  93  of the support body. 
         [0055]    Filter  76 , polarizers  80  and  81 , and focal plane array  82  can be selectively utilized as needed for a desired imaging function. For example, polarizer  80  can be used separately and then in conjunction with polarizer  81  to change the polarization angle of a first and then a second image frame. Each translatable actuator  96  ( FIG. 6 ) is provided with a motor  89  that is connected for the lateral rotation of the given optical element  105 , i.e., the filter  76 , polarizers  80  and  81 , and focal plane array  82 . 
         [0056]    Further, each translatable actuator  96  is provided with a piezo-electric vertical actuator  97  which can incrementally change the incremental up and down orientation of the optical element. Depending on the scale of the reconfigurable sensor device of  FIG. 3 , MEMS (Microelectromechanical System) technology can be utilized in the fabrication of the respective actuators of the device. Thus, filter  76 , polarizers  80  and  81  and focal plane array  82  may be activated to move both laterally and vertically. 
         [0057]    The arrangement and selection possibilities of the respective optical and imaging elements of the reconfigurable sensors,  58 ,  64  are such that uses of the sensor devices include: 1) collecting and storing images in narrow hyperspectral bands of the same scene; 2) collecting and storing orthogonally polarized images of the same scene; 3) collecting and storing images of different resolutions of the same scene; and 4) microscanning an image to capture higher frequencies in the same scene than the sampling rate of the focal plane allows in a stationary position. —These are but a few of the applications for which the reconfigurable sensor systems of the present invention can be utilized. 
         [0058]    With reference to  FIG. 7 , a selectively adaptable optical sensor system  175  which can be utilized as a reconfigurable system  58 ,  64  ( FIG. 2 ) is provided with elongate support  160  that connects to power and communication link  162 . The elongate support  160  is fastened to foundation  170  by fasteners  164  and  166 . Selective locations of the elongate support  160  are provided with a plurality of rotatable motors represented by motors  128 ,  134 ,  140 ,  146 ,  152  and  158  that provide for the rotation of optical elements about an axis of the elongate support  160 . 
         [0059]    Rotatable motor  128  connects to support arm  124  on which an optical element or lens  122  is positioned. The lens  122  in  FIG. 7  is aligned with a target object  195  along an optical axis  120 . Vertical actuator  126  and lateral actuator  127  are provided on a support arm  124  for providing incremental changes in the vertical and/or lateral position of the lens  122 . Actuators  126  and  127  are piezo-electric actuators or their equivalent. Rotatable motor  128  may be further provided with gearing or with piezo-electric, magnetic or other equivalent means for horizontal movement of support  124  along the horizontal axis of elongate support  160 . This allows the lens  122  to be capable of three-coordinate movement. 
         [0060]    Still with reference to  FIG. 7 , rotatable motor  134  is connected to support arm  132  that connects to polarizer  130  and rotatable motor  140  is connected to a second polarizer  136  by support arm  138  thereby allowing the respective polarizers to be moved within and out of the optical path  120  as desired. Rotatable motor  146  is connected to a support arm  144  that connects to filter  142  (an AOTF non-collinear filter is depicted in  FIG. 7 ). Upshifted, undiffracted and downshifted beams of light emanate from the filter  142 . The filtered light can then be detected by focal plane detector  148  which is connected to support arm  150 . Rotatable motor  152  allows the focal plane detector to be rotated to a desired location for detecting the filtered light beams. An auxiliary detector  154  is connected by support arm  156  to rotatable motor  158 . The auxiliary detector can be utilized, if desired, as the operational light detecting element. Thus, by selectively utilizing the respective optical elements in a desired arrangement along optical path  120 , a desired imaging technique can be realized. 
         [0061]    If the sensor system  175  is used as or as part of the reconfigurable sensor device or system  58  of the local image analysis and enhancement center  50 , the image processor  52  and control  60  can be used to actuate and control the sensor system  175 . If the sensor system  175  is used as part of a remote system  64 , the central image processor  52  and control  60  can be used to actuate and control the remote sensor system or, alternatively, a personal computer can be used for controlling the remote sensor system. 
         [0062]    In that the sensor systems of the present invention can be adapted to conform to a variety of optical arrangements, a great number of imaging techniques can be used in conjunction with the present invention. 
         [0063]    In  FIG. 8 , an infrared focal array  200  is depicted which corresponds to the focal array  82  ( FIG. 3 ) and focal array  148  ( FIG. 7 ). In a first step  202 , the infrared focal array  200  transmits an image frame at 0° polarization and in a second step  204  transmits a second image frame at 90° polarization. The image processor  52  grabs a frame of a target image at 0° polarization represented by an image signal V 0  and then grabs a frame of a target image at 90° polarization represented by an image signal V 90 . In a third step  206 , the respective target images represented by image signals V 0  and V 90  are used to assemble an enhanced image formulated by the expression (V 0 −V 90 )/(V 0 +V 90 ). 
         [0064]    In  FIG. 9 , the present invention is utilized to obtain an enhanced polarization difference image by obtaining a first focused image of a target at a 0° reference orientation in step  208  and by obtaining a first polarized defocused image of the target at the 0° reference orientation in step  210 . 
         [0065]    A second focused image of the target at a 90° orientation is obtained in step  216  and then a second polarized defocused image at the 90° orientation is obtained in step  218 . In step  212 , the first polarized defocused image is subtracted from the first focused image to obtain a value V 0 , and in step  220  the second polarized defocused image is subtracted from the second focused image to obtain a value V 90 . The values V 0  and V 90  are then stored in steps  214  and  222 , respectively. Then in step  224 , the values V 0  and V 90  are utilized in a mathematical expression (V 0 −V 90 )/(V 0 +V 90 ) which represents the enhanced polarization difference image. 
         [0066]    In  FIG. 10 , the present invention is utilized to obtain a focused microscanned image in a first step  226  and to obtained an unfocused microscanned image in a second step  228 . The unfocused microscanned image is then subtracted from the focused microscanned image in step  230  to obtain an enhanced microscanned image. 
         [0067]    With reference to  FIG. 11 , the present invention can be used to obtain an enhanced image with no aliasing distortion by first obtaining a non-polarized full focus image of a target scene or object in a first step  240  (e.g., without utilizing a polarizer with the lens  70 ,  122 ) and then microscanning and storing the image in a second step  250 . In a third step  260 , an out-of-focus image of the image target is obtained and in step  270  a microscanned out-of-focus image of the image target is stored. In step  280  the microscanned out-of-focus image is subtracted from the microscanned full focus image to obtain a result  290  which is an enhanced image without aliasing distortion. 
         [0068]    With reference to  FIG. 12 , the present invention may be used to receive a full focused image at 0 degrees polarization (e.g., utilizing lens  70 ,  122  with a polarizing means giving 0 degree polarization angle) in a first step  300  and then microscanning the image (e.g. utilizing hyperspectral filter  76  and focal plane array  82 ) in a second step  310  and storing the image. In a third step  320 , the lens  70 ,  122  is moved to an out-of-focus position and the received image is polarized at 0 degrees with the out-of-focus image being microscanned and stored in step  330 . In step  340 , the out-of-focus microscanned image obtained at 0 degrees polarization is then subtracted from the full focus, microscanned image that was obtained at 0 degrees polarization to obtain a 0 degree polarization image with no aliasing distortion in step  350 . In steps  360  and  370  the process is repeated for an image taken at a 90 degree polarization angle. 
         [0069]    The selectable and interchangeable optical elements in the reconfigurable sensor devices  58 ,  64 ,  90 ,  175  of the present invention allow images to be received by the signal processor that contain various properties thereby allowing a more optimal image for a given task to be realized by imaging enhancement. These different properties include different polarizations, different wave bands, and different resolutions or images with reduced aliasing. 
         [0070]    The reconfigurable imaging may be controlled both locally and remotely by an operator located at a local enhancement center, or the remote reconfigurable sensor system can be controlled by an operator using computer control means at the remote location. The image storage depository  56  of the present invention allows images from various remote locations to be stored along with locally-obtained images and allows the image processing of images obtained at different locations. 
         [0071]    Various modifications are possible without deviating from the spirit of the present invention. Accordingly the scope of the invention is limited only by the claim language which follows hereafter.