Algorithm for quickly and accurately calculating circularity of sandstone

The invention relates to an algorithm for quickly and accurately calculating the circularity of sandstone. The algorithm comprises the following steps: acquiring a contour line and a two-dimensional coordinate of a single sandstone particle image; calculating the area G of the gravel particles; any point in the contour line is selected as an initial circle center coordinate, the maximum distance between the initial circle center coordinate and a point on the contour line is used as an initial radius R0 to form a circumcircle, and the circumcircle and the contour line form a plurality of intersection points; carrying out vector superposition and unitization on the initial circle center pointing to the intersection point of the circumcircle and the contour line to form a displacement vector, moving the initial circle center along the direction of the displacement vector to obtain a new circle center, repeatedly carrying out iteration according to the formed new circumcircle until the radius R '0 of the circumci