图像面积百分比测量的误差分析

Error Analysis of Image Area Percentage Measurement

以单晶高温合金中疏松和残余共晶的测量为例,分析金相分析中用图像法测量面积比结果的误差。结合实验及理论分析,测量结果的误差主要来源于图像色彩及人为认知的待测对象的色域范围,表现为被测对象的“边界像素”是否被定义。通过实验获得了不同放大倍数、色彩阈值时,疏松和残余共晶含量测量结果,参数对2种测量对象的影响规律类似,测量值随选定色彩阈值范围的增大而增大,且放大倍数较大时,变化程度总体上变小。在某个色彩阈值时,各放大倍数对应的测量结果较相近。实际应用中,可以通过规定相对合理的放大倍数来减少人为认知和其他因素偏差的影响,兼顾效率与准确性,达到评估和控制测量结果的误差的目的。

Analysis of image area percentage measurement error was carried out for the measurement of porosity and residual eutectic in a single-crystal superalloy as an example.Synthesizing the experimental and theoretical analysis results,it is found that the error of the measurement results mainly comes from the image color and the color gamut range of the object to be tested.In other words,the measurement error mainly comes from whether the“boundary pixels”of the object have been defined.The measured results of porosity and residual eutectic content were obtained through experiments at different magnification multiples and color thresholds.The influence law of parameters on the two measured objects is similar.The measured value increases with the increase of the range of selected color threshold,and the change degree generally decreases with the larger magnification multiples.At a certain color threshold,the measurement results corresponding to each magnification are similar.In practical application,the effect of cognitive and other biases can be reduced by setting relatively reasonable magnification,and the efficiency and accuracy can be improved,so as to evaluate and control the error of measurement results.