Nitrogen-containing fused ring compound having at least one structural unit selected from the group consisting of a structural unit represented by the formula and a structural unit represented by the formula. Initially, a link from a local network site to a remote network site utilizing a communications application while multi-tasking applications are simultaneously running at the local network site is initiated. The ink ejection amount error of each same ink nozzle array is determined based on the color specification values of the plurality of color patches for each same ink nozzle array.