1. A method of picking up images of substrates and creating a substrate image being a defect inspection reference on a basis of a plurality of the picked-up substrate images, comprising: a component decomposition step of decomposing a planar distribution of pixel values in the picked-up substrate image into a plurality of pixel value distribution components through use of a Zernike polynomial for each of the substrate images; a Zernike coefficient calculation step of calculating Zernike coefficients of the pixel value distribution components decomposed through use of the Zernike polynomial; a Zernike coefficient extraction step of extracting, for every Zernike coefficients having a same couple of degrees, from the calculated Zernike coefficients, (1) a median value, and (2) values deviated from the median value by a predetermined value or more; an image specification step of specifying substrate images having the extracted values; and an image creation step of creating a substrate image being a defect inspection reference by combining the specified substrate images.