a. In addition to the loss of small-sized spots, the low print resolution may also result in the loss of edges of large-sized spots, resulting in the circular area captured using OpenCV being smaller than the set size. b. Poor quality printing ink/paper could cause spreading or condensation of the ink on the paper, which can also affect measurement of spot size. c. The parameter setting of the blob filter in Python is an unavoidable error, and it is necessary to debug the detector parameters many times to obtain the parameters with the smallest error.