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Improved Infrared Imaging with Variable Resolution Achieved via Post-Processing


TECHNOLOGY AREA(S): Sensors, Electronics, Battlespace 

OBJECTIVE: Develop imaging technology in the Mid Wave Infrared (MWIR) band with variable resolution achieved via software-coded post-processing algorithms that reduces cost and provides higher effective-resolution. 

DESCRIPTION: Mid Wave Infrared (MWIR) imaging systems are widely useful in both day and night operation since they measure thermal signatures of objects in the scene. At present, MWIR imagers deployed throughout the surface Navy are primarily associated with specific weapon systems. These sensors provide aim-point selection, fine tracks, and target recognition and identification at long ranges. These imaging systems must possess high angular resolution (10s of micro radians), provide full motion video outputs and have high sensitivity in order to achieve these objectives. However, there is an increasing need for MWIR imagers to provide situational awareness in congested waters, especially when operating conditions do not permit the effective use of radar. In these circumstances, the primary MWIR sensor requirements are wide field of view and high sensitivity. The requirements for target recognition, identification, and aim point selection and those for providing situational awareness are currently met by two approaches. In the first instance, MWIR imagers associated with specific weapon systems are used in a scanning mode in order to cover the required field of regard (typically full panoramic 360 degree coverage is desired). The second approach employs two separate MWIR imaging systems “ one with a panoramic field of view, moderate resolution (200 micro radian), and moderate frame rate (2 Hz) and a second imager with a narrow field of view (NFOV) and high resolution on a rotating mount that is steered in response to cues provided by the wide field of view (WFOV) system. In order to provide the needed general situational awareness and target detection, the first solution is not acceptable since it requires using the heavy gun mount to steer the dedicated NFOV imager. This results in needless and accelerated wear and tear on a critical weapon system. Furthermore, in non-hostile waters, it is typically against the rules of engagement to point a weapon system at another vessel without provocation. The second solution (a WFOV imager cueing a NFOV imager) becomes inordinately expensive because it requires using two completely independent yet coordinated imaging systems, which need a large number of high-resolution focal plane arrays. The cost, size, weight, and power consumption of MWIR imagers are dominated by the focal plane arrays and their associated cryogenic cooling systems. Large focal plane arrays are disproportionately higher in cost due to the lower production yields of large scale devices and the simple fact that fewer large devices are obtained from a given size semiconductor wafer. Therefore, it is desirable to find a solution that reduces the requirement on MWIR focal plane array size and number. For example, if a one Megapixel MWIR focal plane array could provide the same effective system level performance achieved by a sixteen Megapixel focal plane array, the resulting cost savings will be very significant. Observation shows that in a typical scene, only a small fraction of the field of view contains objects that need further inspection with higher spatial resolution. Imaging an entire wide field of view scene with a high angular resolution MWIR imager is extremely inefficient. This can be mitigated by digital super resolution. Digital super resolution is a well-established technique for achieving image resolution that is greater than that fundamentally obtained by the focal plane array while staying within the performance limits of the imaging optics. However, most demonstrated systems provide only modest improvement (around two times). The Navy seeks infrared imagers with variable resolution achieved via post-processing to reduce the overall cost of infrared imaging. The technical approach should enhance the detector-limited resolution of a MWIR imager by a minimum (threshold) of four times along each axis (with ten times enhancement as an objective), thereby providing sixteen times more effective pixels (as compared to the actual physical pixels) in a focal plane array. Such resolution enhancement can be restricted to regions within the field of view where objects of interest are detected via the coarse resolution image captured at the native resolution of the focal plane array. The desired solution will increase the complexity of the optical system minimally and will require post detection computation easily performed in real time over a small image segment (100 by 100 pixels). The technology sought is intended for video images and the video data (and associated metadata) should conform to the specifications set by the Motion Imagery Standards Board. A hardware-independent solution is desired. Software enhancement of effective resolution will reduce the fundamental resolution (number of pixels) of the many focal plane arrays required. The result will be either smaller, cheaper, focal plane arrays or fewer focal plane arrays per system. Implementation of functionality in software enables faster and potentially cheaper future technology upgrade to the imaging system. A secondary benefit is realized in reducing the numbers of cryogenic coolers required, as a separate cooler is typically needed for each focal plane array. 

PHASE I: The small business will define and develop a concept for infrared imagers with variable resolution achieved via post-processing in the MWIR waveband. The company will demonstrate the feasibility of their concept in meeting Navy needs and will establish that their concept can be feasibly implemented. Feasibility will be established by some combination of initial (not in real-time) prototype algorithm testing, analysis, and modeling, and using simulated video data. The company will also demonstrate, by some combination of analysis and/or modeling, that the concept increases effective resolution thereby increasing focal plane array efficiency and reducing imager cost. The Phase I Option, if awarded, should include the initial layout and capabilities specifications to build the prototype in Phase II. 

PHASE II: Based on the Phase I results and the Phase II Statement of Work (SOW), the small business will produce and deliver prototype infrared imagers with variable resolution achieved via post-processing in the MWIR waveband. The prototype will be refined and optimized to achieve the objectives stated in the description. The company will test and demonstrate the prototype to establish performance under a variety of relevant conditions and the results will be evaluated to determine the technologys capability in meeting Navy requirements. Although this is primarily a software effort, the company may need to design, purchase, build, or otherwise implement some hardware to fully demonstrate capability. The company will prepare a Phase III development plan to transition the technology for Navy and potential commercial use. 

PHASE III: The company will support the Navy in transitioning the technology to Navy use. The company will further refine infrared imaging technology with variable resolution achieved via post-processing according to the Phase III development plan for evaluation to determine effectiveness and reliability in an operationally relevant environment. Since a hardware-independent solution is desired, the expected technology shall consist of software-coded algorithms that can be deployed and supported on a variety of processors as part of larger MWIR sensor platforms. The company will support the Navy for test and validation to certify and qualify initial production components for Navy use. The final product will be produced by the company and will transition to the Government either directly or through Government prime contractors for use in Navy systems. Private Sector Commercial Potential: Imaging is a field with large commercial as well as industrial and military markets. Although this topic addresses a need in the MWIR waveband, the technology can likely be applied in the visible band as well. Since the desired technology would reduce cost in imaging systems, any advances made in this area will undoubtedly find other applications such as surveillance cameras, aerial imaging, and potentially even commercial photography. 


1. Su, Heng, et al. Spatially Adaptive Block-Based Super-Resolution. IEEE Trans. Image Processing 21, March 2012: 1031-1045.

2. Su, Heng, et al. Super-Resolution Without Dense Flow. IEEE Trans. Image Processing 21, April 2012: 1782-1795.-


KEYWORDS: Resolution Enhancement; Super Resolution; Effective Resolution; Mid Wave Infrared; Focal Plane Arrays; Infrared Imaging 

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