一种相变热图的图像处理方法

相变热图技术中,为了得到风洞试验模型表面的热流分布,必须对相变热图序列进行相变线提取.首先通过特殊的时-空变换,将所有原始序列图像的直接分割转化为对少量合成图像的分割,在减小计算量的同时较好地解决了原始图像中由于相变区域模糊而难以分割的问题.同时,为了解决由于模型表面存在镜面反射造成的模型头部区域相变线提取不准确,引入镜面反射模型,并通过分割和参数求取过程的迭代执行计算出反射模型各参数,对合成图像进行整体性亮度补偿并最终得到良好的分割结果.最后根据提取出的相变线位置和材料相变温度,完成热流值的计算.通过比较表明本文结果更为准确合理,也验证了所提出分割方法的有效性,促进相变测温技术的广泛应用.

The image processing of phase change thermography

To calculate the surface heat transfer rate of the experimentation model in wind tunnel,the isotherms should be extracted firstly from the phase change thermography sequences.In this paper,the segmentation which is not for all original images but several synthesized images is performed through the special time-space transformation to reduce the computation cost as well as to simplify the segmentation.Then to compensate the brightness of the synthesized images of the front region,the illumination model is introduced and its correlative parameters are computed by iteration method.Finally,the surface heat transfer rate of the experimentation model is calculated based on the temperature of the phase change materials and the positions of the isotherms which are obtained from the synthesized images.The eventual results are proved to be more precise and rational than the method used before,which adequately demonstrates the efficiency of the segmentation method.The proposed method will promote the application of phase change thermography.