Image reading apparatus and image reading method for performing background removal processing on image data

Patent metadata

Field	Value
Publication number	US-10021272-B2
Application number	US-201615251891-A
Country	US
Kind code	B2
Filing date	Aug 30, 2016
Priority date	Mar 22, 2016
Publication date	Jul 10, 2018
Grant date	Jul 10, 2018

Abstract

An image reading apparatus includes an image data obtaining unit, a foreign material position information obtaining unit, and a separation processor. The image data obtaining unit obtains image data read from a document passing over a read area. The foreign material position information obtaining unit obtains foreign material position information read from the read area in which the document is not present. The separation processor separates the image data into plural objects including a background object, detects, by using the foreign material position information, a streak image portion caused by foreign material in the read area and included in the image data, and assumes a pixel of the streak image portion to belong to the background object if the pixel is present in the background object and has a pixel value equal to or smaller than a threshold determined in accordance with a representative value of the background.

First claim

What is claimed is:

1. An image reading apparatus comprising:
an image processor configured to act as:
an image data obtaining unit that obtains, as image data, a read signal read from a document that passes over a read area;
a foreign material position information obtaining unit that obtains, as foreign material position information, a read signal read from the read area in which the document is not present; and
a background removing unit; and

a separation processor that separates the image data into a plurality of objects including a background object corresponding to a background of the document, detects, by using the foreign material position information, a streak image portion that is caused by foreign material present in the read area and that is included in the image data, and performs a process for assuming a pixel of the streak image portion to belong to the background object if the pixel is present in the background object and has a pixel value equal to or smaller than a threshold determined in accordance with a representative value of the background, wherein
when separating the image data into the plurality of objects, the separation processor separates a pixel of the streak image portion having a pixel value equal to or smaller than the representative value of the background as a pixel belonging to the background object, and assumes and separates a pixel of the streak image portion having a pixel value larger than the representative value of the background as a pixel belonging to a line object, and
the background removing unit converts a pixel value of a pixel that belongs to the background object separated by the separation processor by using a relationship between an input value and an output value and by using the pixel value as the input value, and converts a pixel value of a pixel that is present in the background object and that is assumed, by the separation processor, to belong to the line object into the representative value of the background.

2. An image reading method comprising:
obtaining, as image data, a read signal read from a document that passes over a read area;
obtaining, as foreign material position information, a read signal read from the read area in which the document is not present;
separating the image data into a plurality of objects including a background object corresponding to a background of the document, detecting, by using the foreign material position information, a streak image portion that is caused by foreign material present in the read area and that is included in the image data, and performing a process for assuming a pixel of the streak image portion to belong to the background object if the pixel is present in the background object and has a pixel value equal to or smaller than a threshold determined in accordance with a representative value of the background, wherein
when separating the image data into the plurality of objects, the method further comprises separating a pixel of the streak image portion having a pixel value equal to or smaller than the representative value of the background as a pixel belonging to the background object, and assuming and separating a pixel of the streak image portion having a pixel value larger than the representative value of the background as a pixel belonging to a line object; and
converting a pixel value of a pixel that belongs to the separated background object by using a relationship between an input value and an output value and by using the pixel value as the input value, and converting a pixel value of a pixel that is present in the background object and that is assumed to belong to the line object into the representative value of the background.

Assignees

• Fuji Xerox Co Ltd

Inventors

• Namiki Tatsuya
• Matsuguma Chihiro
• Arai Noriko
• Ueda Kenji
• Ishikawa Yurie

Classifications

• H04N1/403

  Discrimination between the two tones in the picture signal of a two-tone original · CPC title

• H04N1/4092

  Edge or detail enhancement · CPC title

• H04N1/4072

  dependent on the contents of the original · CPC title

• H04N1/00092

  relating to the original or to the reproducing medium, e.g. imperfections or dirt (detecting properties of a sheet H04N1/00681) · CPC title

• H04N1/00084

  Recovery or repair, e.g. self-repair · CPC title