Heat source recognition in PCB infrared thermal image based on B-spline wavelet transform

Heat sources recognition is very important for Printed Circuit Board (PCB) infrared thermal imaging diagnosis and several recognition techniques have been proposed by former researchers. In this paper the heat sources detection based on wavelet transforms is investigated. Cubic B-spline function is chosen as the smoothing function and its first derivative as the wavelet function. Fast recursive decomposition algorithm for 2-dimensional signal is used to compute wavelet transforms at different scales. Then the temperature gradient distributions on the thermal image of PCB under test can be determined and the bound of the heat sources can be located on the base of the gradient information. Multi-scale edge detection technique offered an opportunity to recognize the heat sources at the same time distinguishing them from the noises by choosing proper detection scale. Experimental results suggest that heat source in PCB thermal image can be recognized successfully using the proposed method.