A high-performance hand-held thermal imaging camera has been developed, based on a 320×256-element InSb infrared focal plane array (FPA) operating in the medium-wave infrared region. The primary design objective was a low-cost, compact, lightweight, and portable thermal camera with a recognition range of 2 km. A staring FPA based on InSb technology with long and variable integration time provides the answer best suited to these requirements. The system provides such features as two-point and adaptive nonuniformity correction, bad-pixel detection and replacement, dynamic range compression, contrast and edge enhancement, histogram equalization, and digital scan conversion for CCIR-B-compatible output. The design methodology and the performance are presented.
Present day thermal imaging systems are designed based on highly sensitive infrared focal plane arrays (IRFPA), in which most of the preprocessing is done on the focal plane itself. In spite of many advances in the design of IRFPAs, it has inherent non-uniformities and instabilities, which limits its sensitivity, dynamic range and other advantages. Whenever there is little or no thermal variation in the scene, the thermal imager suffers from its inability to separate out the target of interest from its background. Thus, most of the infrared imagery suffers from poor contrast and high noise. This results in object not being visible clearly. The problem becomes complicated because of dynamic background and non-availability of background clutter characteristics. In this paper, we present a adaptive approach for image contrast enhancement that expands the range of the digital numbers in a self-adaptive manner. This algorithm has been tested on the field-recorded data and is observed that this technique offers excellent results for thermal imager operating in both 3-5 μm and 8-12 μm wavelength regions.
A fully reconfigurable architecture for realizing thermal imaging system is proposed. This architecture provides a generic solution to any signal processing issues related to thermal imaging and also provides the advantage of low power design and take care of any sensor up-gradation. The proposed architecture is implemented by using Xilinx Virtex II 2000K gate FPGA and 320 x 256 elements InSb IRFPA. The system can store up to six gain and offset tables which can be optimized for different environmental conditions and as well us allow the up-gradation of offset coefficients dynamically. Image frames are presented which shows the successful implementation of the architecture.
A high performance hand held thermal imaging camera has been developed based upon 320 x 256 elements InSb focal plane array (FPA) operating in MWIR region. The primary design goal of this camera was to design a low cost, compact, lightweight and man portable thermal camera with a recognition range of 2 Km. A staring FPA based upon the InSb technology with long and variable integration time provides the answer best suited under these requirements. The system provides the various features such as non-uniformity correction (NUC), bad pixel detection and replacement (BPR), contrast enhancement, histogram equalization and digital scan conversion for CCIR-B compatible output. The design methodology and the performance are presented.