1. A non-transitory storage medium storing an image processing program causing a computer to execute processing of: acquiring, on a first image of a captured marker having a pattern formed by a plurality of first areas which has a first color and a plurality of second areas which has a second color that is different from the first color, a position of a first point where the plurality of first areas and the plurality of second areas cross; acquiring, on the first image, a boundary between one of the plurality of the first areas and one of the plurality of the second areas having the first point; converting the first image to a second image having a plurality of pixels to other positions with pixel values by using the position of the first point, the position of a second point present on the boundary and the positions of the plurality of pixels included in the first image and the pixel values of the plurality of pixels; scanning on the second image; acquiring an expectation value indicating a possibility that an intersection where the plurality of first areas and the plurality of second areas cross exists excluding the first point; acquiring the position of the intersection on the second image on the basis of the expectation value; inverting the other positions of the plurality of pixels included in the second image to the corresponding positions on the first image; acquiring the position of the first point and the position of the intersection on the first image; and determining the acquired position of the first point and the position of the intersection as the positions of features of the pattern.