Image forming apparatus, recording medium in which test-pattern image forming program is recorded, test-pattern image forming method, and skew angle calculation method

Abstract

An image forming apparatus equipped with a first image forming unit, plural second image forming units, and a test-pattern image forming control unit for controlling the first and second image forming units which controls the first and second image forming units to form a test-pattern image, in such a manner that first and second marks of different densities are disposed adjacent to one another, based on test-pattern image data. This test-pattern image data includes first data serving to arrange a plurality of first color lines, which have each a predetermined line width, at a predetermined pitch by the first image forming unit, second data serving to form the first mark overlapping with the plural first color lines by the second image forming units, and third data serving to form the second mark displaced in a direction perpendicular to the plural first color lines. Before shipping the apparatus from a factory or when inspecting or repairing the apparatus at user's site, the customer engineer can easily grasps causes for possible positional errors using this simple test pattern and hence can cope with such trouble by exchanging or adjusting positions of parts comfortably and efficiently.