Patent ID: 8646869

Claim:
A recording position error measurement apparatus, comprising: a read image signal acquisition device which acquires a read image signal of a test pattern recorded on a recording medium by a plurality of recording elements while causing relative movement between the recording medium and a recording head in which the plurality of recording elements are arranged; and a signal processing device which carries out processing for analyzing the read image signal so as to identify recording position errors of the plurality of recording elements, wherein: the test pattern includes line-shaped patterns which are recorded by operating the recording elements corresponding to projected recording elements selected at an interval of a fixed detection pitch number PP, from among an alignment of projected recording elements obtained by projecting the plurality of recording elements of the recording head onto a straight line parallel to a first direction that is orthogonal to a direction of the relative movement; when an interval between the projected recording elements aligned in the first direction is represented by a recording pixel pitch WP, a pixel size in the first direction of read image data acquired by the read image signal acquisition device is represented by a read pixel pitch WS, and a group of a plurality of read pixels aligned continuously in the first direction which forms an analysis unit for analyzing the read image signal is represented by an analysis pitch number PS, then a period T determined by T=WP×PP÷|WS×PS−WP×PP| is three or greater in units of pixels of the read image signal; and the signal processing device has: a dividing device which divides pixel series of the read image signal into sequences having different remainder values so as to generate image signals of the respective sequences, the remainder values being obtained respectively by dividing read pixel numbers by the analysis pitch number PS, the read pixel numbers being respectively assigned as consecutive integers, in alignment sequence, to pixels which are aligned in the first direction with respect to the acquired read image signal; a prediction signal generation device which calculates regular prediction signals which are predicted with respect to the respective sequences, according to the read image signal; a threshold value determination device which determines tone value differences corresponding to respective distances representing recording position errors from the prediction signals, and which determines threshold values corresponding respectively to the recording position errors, from the tone value differences; a change signal calculation device which calculates a change signal indicating a difference between the prediction signal and the image signal of each of the sequences; and an error distance calculation device which specifies the recording position errors of the plurality of recording elements in the recording head according to comparing the change signal with each of the threshold values.