Patent ID: 9389565
Filing Date: 2016-07-12
CPC Classification: G03G,H04N

Claim Text:
1. A color registration method of an image forming apparatus, comprising: printing a preset test pattern for color registration on a printing paper; generating a scan image by scanning the printing paper on which is printed the preset test pattern for color registration; detecting the printed test pattern for color registration from the scan image; calculating location error values of respective colors, using the detected test pattern for color registration; and performing the color registration using the calculated location error values of respective colors, wherein the preset test pattern for color registration comprises a plurality of pairs of a first color line and combined lines of a second color line, a third color line, a fourth color line, a fifth color line, and a second color line in sequence, and the first color is one of cyan C, magenta M, yellow Y, and black K, and the second, third, fourth and fifth colors are different colors from each other with one of each of cyan C, magenta M, yellow Y and black K, wherein the detecting the printed test pattern for color registration comprises detecting the printed test pattern for color registration by detecting the first color line from the scan image, and the calculating comprises: wherein the calculating the median location values of respective color lines constituting the combined lines comprises: calculating the median location values based on middle locations of a distance between the calculated linear equations of the first and second edges.