热流场层析图的预处理实验研究

热流场的层析图是一些以条纹为主要特征的流场信息记录。条纹分析无论对干涉层析术还是对莫尔层析术都是较为关键的步骤。如何从各种噪声尤其是强烈的不均匀背景光噪声中提取清晰完整的条纹是热流场层析图预处理的主要问题。本文从热流场层析图的特征入手，修正灰度直方图重心，引入可提取概率作为区分噪声和信号的判据，将灰度图像依据由图像性质决定的投影函数投影到概率平面上，进行迭代以增强信号，衰减噪声。事实证明，本文所提

Experimental Study on Image Preprocessing of Thermal Flow Field Tomogram

Tomograms of thermal flow field are the information records characterized of fringes. Fringe analysis is a critical step both for interferometric and Moire tomography. How to extract clear and intact fringes from all kinds of noises, especially strongly inhomogeneous background illumination, is the key problem in preprocessing of thermal flow field tomogram. The characteristics of thermal flow field are analyzed and a probability filter method is developed, in which the center of image histogram is corrected, a so-called “extractable probability” is introduced as the standard for identifying signal from noise. According to a projection function determined by image features, gray image is projected into its probability plane where iterative signal enhancing and noise reduction are performed. It is proved that the probability filter presented in this paper is effective to the tomograms of thermal flow field.