After processing the data, it was calculated that the average measurement error of the detection method for diameter is -15%, and the average measurement error for area is -25%. There is a relationship between diameter and area: area=(π×diameter²)/ In addition, it should be noted that the test error in this project is mainly affected by three factors: the printing resolution of the printer, the quality of the printing ink/paper and the parameter settings of the blob filter in the Python code.