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Development and Application of a Universal Filter in Image Processing for Automatic Interpretation of Temperature-Sensing Thermal Paints



Machines like Internal Combustion Engines and gas turbines work on the principle of converting the heat energy into mechanical energy. Every effort is taken to elevate the operating temperature which in turn increases the output efficiency. However, the engine components cannot withstand such high temperatures and their life is seriously affected. The true gradient of the temperature to which these engine components are exposed is a wealth of knowledge for an engine designer. Conventional thermometry has got many limitations from measuring and mounting point of view and is unable to give the exact thermal gradient. Advancement in thermal mapping technique is required to enhance the development of these components. Comparatively thermal paints provide a better alternative to be used as temperature sensors. These paints change their color permanently when exposed to temperature. A proper calibration and automatic interpretation of these paints using digital image processing gives a reliable thermal contour. During the engine testing the carbon exhaust from the engine blackens the color of the thermal paint applied on the various components as it flows across it creating an obstacle in the color pattern (temperature) recognition. This article highlights the efforts taken in development and application of a filter which removes the effect of the carbon soot to denoise the degraded image and recover the original image to get the required temperature profile.