An image processing system comprises: a projector for projecting pattern light whose coordinate component at least in one direction is determinable; an imaging apparatus for imaging an object illuminated with the pattern light to acquire a pattern image; and a controller including a calculator for calculating the 3D coordinates of a point on the object based on the pattern light and the pattern image. The calculator determines a first point on the pattern image; calculates a second point corresponding to the first point in a pattern-light projection plane; calculates a third point based on the second point in the projection plane, a nonlinear line in the projection plane calculated by analyzing the pattern image, and an epipolar line in the projection plane calculated based on the first point; and calculates the three-dimensional coordinates of the point on the object based on the first point and the third point.