A method for generating ejection position data indicating an ejection position where ink is ejected includes performing an edge detection process, an edge correction process, and an ejection position data generation process based on processing target data indicating an image to be printed. In the processing target data, a non-ejection value indicating that ink is not ejected to a corresponding ejection position or an ejection value other than the non-ejection value is set as a pixel value of a pixel. In the edge detection process, a position where a pixel to which the non-ejection value is set and a pixel for which the ejection value is set are adjacent is detected to detect an edge. In the edge correction process, the pixel value of the corresponding pixel is changed to a non-ejection value for at least a part of the ejection position where ink is ejected to draw the edge.