PROBLEM TO BE SOLVED: To provide an image processor which can uniformly represent the sizes of thin lines simply, and an image processing method or the like. SOLUTION: Thin lines are extracted from drawing data (step S11). Upon extracting the thin lines, a thin line extracting unit 14 extracts as thin lines the lines whose width is narrower than a predetermined threshold value. Whether the extracted thin lines satisfy the predetermined condition or not is determined(step S12). Concretely, an angle of inclination is checked to determine whether it is 45°or 135° or not from a specified reference axis (horizontal axis). When the predetermined condition is determined not be satisfied, bit map data is produced from the drawing data as it is as printing data (step S14) and print data or the like is transmitted to a printing device. Meanwhile, when the predetermined condition is determined to be satisfied, a process for shifting one terminal point of the thin line is effected (step S13). Then, bit map data is produced from the drawing data after processing as printed data (step S14) and print data or the like is transmitted to the printing device. COPYRIGHT: (C)2009,JPO&INPIT