Image forming apparatus and image forming method for printing a sequential pattern

An image forming apparatus to perform printing on each of a plurality of sheets of paper, comprising:

• a communication section for receiving print data for printing a printing image and an additional image on each sheet of paper from the plurality of sheets, wherein
• any one region of the additional image is expressed in a first color, the additional image including a predetermined number of regions which are provided at an end part of each sheet of the plurality of sheets of paper and which are continuous in an extending direction of the end part of the sheets;
• and
• the remaining regions from the predetermined number of regions of the additional image are expressed in a second color,
• the image forming apparatus further comprising:
• a control section to synthesize, on each sheet of paper, the additional image, wherein the one region of the additional image expressed in the first color is shifted sequentially in the extending direction of the end part of the sheets, with the printing image, in an order of the printing of each sheet of paper;
• and
• a printing section to print the synthesized image, wherein
• the addition image includes a plurality of images,
• the predetermined number of regions are respectively provided for a plurality of number which differ from each other,
• the control section synthesizes the plurality of additional images, which respectively correspond to the plurality of numbers which differ from each other with the printing image, in the end part of each sheet at positions which differ from each other, and
• when the printing is performed normally to each sheet of paper and when each sheet of paper is layered on each other in order, a geometric pattern is formed with respect to each region on a side surface of a bundle of sheets of paper, each geometric pattern being different from each other.