能量累积在红外热图像序列处理中的应用

Application of Energy Accumulation in IR Thermal Image Sequences Processing

针对飞机结构隐藏腐蚀热波成像检测中出现的试件表面存在杂物、热像仪中有用数据较少、图像序列中腐蚀区域不明显等情况,首先通过对加热前的一幅图像进行自适应形态学锐化处理,提高图像的对比度,并根据图像梯度的变换情况确定出杂物的位置。其次对加热后的图像序列在相同的位置采用(5×5)模板进行最小值滤波,将杂物滤除掉。然后采用Daubechies9/7小波对图像序列进行变换,并分析了主动式热波图像能量的分布情况,对能量集中的低频部分进行累积,降低高频部分的能量,在此基础上对图像进行重构。最后对重构前和重构后图像的质量进行了定量评价。实验结果表明,该方法可以有效的提高图像的质量,降低图像的噪声,得到易于判读的红外热图像。

The paper solved the problems of less valid data in thermal infrared imager, impurity being on surface of specimen and uneasy dipartite corrosion area in image which happened in detection of structure parts＇ hidden corrosion by thermal wave imaging. Firstly, the contrast of one unheated image was enhanced by self-adaptive mathematical morphology sharpening, and then location of the impurity was confn-med by change of the image grads. Secondly, the impurity in post-heated image sequences was filtered based on minimum of （5×5） template at the same impurity location. Thirdly, the sequence of images was transformed based on wavelet Daubechies9/7. Low frequency＇s energy was cumulated and high frequency＇s energy was reduced through analyzing distribution of the active thermal image＇s energy. And then the thermal image was reconstructed. Finally, quantitative evaluation was presented between the reconstructed image and the original image. The experimental result indicates that the method can improve the quality of IR thermal image, reduce noise of IR thermal image, and obtain identified IR thermal image easily.