IMAGE PROCESSING METHOD AND PROGRAM STORAGE MEDIUM

• US 20110002015A1
• Filed: 06/25/2010
• Published: 01/06/2011
• Est. Priority Date: 07/04/2008
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Kitagawa, Kan, Hattori, Yusuke, Hayakawa, Mizuki
• Granted Patent: US 8,630,026 B2
• Time in Patent Office: Days
• US Class Current: 358/448
• CPC Class Codes: H04N 1/00795 Reading arrangements details of scanning heads H04N1/024; scanning arrangements therefor H04N1/04
• CPC Class Codes: H04N 1/00816 Determining the reading area, e.g. eliminating reading of margins
• CPC Class Codes: H04N 1/1017 the main-scanning components remaining positionally invariant with respect to one another in the sub-scanning direction
• CPC Class Codes: H04N 1/193 using electrically scanned linear arrays , e.g. linear CCD arrays
• CPC Class Codes: H04N 1/38 Circuits or arrangements for blanking or otherwise eliminating unwanted parts of pictures H04N1/387 takes precedence

Abstract

There is provided an image processing method which determines the area of a document from an image read on a transparent platen, the image processing method also determines a single object area or a plurality of object areas from the image on the transparent platen, and when the luminance of the area in which the object area is removed from the image on the transparent platen is detected to determine the document area, the image processing method detects whether or not an image of a shadow exists around the periphery of the object area on the image of the transparent platen, and the threshold value used for determining the document area is different depending on whether a shadow is detected.

Claims

1. An image processing method comprising:

reading an image on a transparent platen on which a single document or a plurality of documents is placed and which is covered by a platen cover, through the transparent platen;

determining a single object area or a plurality of object areas from the image on the transparent platen (a first determination);

determining an area including all the object areas determined in the first determination as a first area (a second determination);

determining a set of the object areas determined in the first determination as a second area (a third determination);

determining an area in which the first area is removed from the image on the transparent platen, as a third area and determining the feature quantity of the image in the third area as a first feature quantity (a fourth determination);

determining an area in which the second and the third area are removed from the image on the transparent platen, as a fourth area and determining the feature quantity of the image in the fourth area as a second feature quantity (a fifth determination); and

determining that, if a difference between the first and the second feature quantity is equal to or smaller than a first threshold value, each of the object areas is an image of each of a plural documents and, if the difference is greater than the first threshold value, the first area is an area of one document;

wherein the image processing method further comprises detecting whether an image of a shadow exists around the periphery of the object area on the image of the transparent platen, the shadow exist if the object is a thick document, and if the shadow is detected, a second threshold value greater than the first threshold value is used in the above determination instead of the first threshold value.

2. The image processing method according to claim 1, wherein the feature quantity of the image is a histogram of the number of pixels corresponding to the luminance value of each pixel of the image and a luminance value at which accumulation of a frequency exceeds a third predetermined threshold value.

3. The image processing method according to claim 1, wherein it is determined that the image of a shadow exists if a small-area image adjacent to the object area gradually becomes bright according as the image is away from the object area, on the side opposite to the position where illumination for reading the transparent platen is provided, relative to a document.

4. A storage medium which can be read by an information processing apparatus connected to an image reading apparatus and to which a program code executed by the information processing apparatus is stored, the program code comprising:

reading an image on a transparent platen on which a single document or a plurality of documents is placed and which is covered by a platen cover, through the transparent platen by controlling the image reading apparatus;

determining a single object area or a plurality of object areas from the image on the transparent platen (a first determination);

determining an area including all the object areas determined in the first determination as a first area (a second determination);

determining a set of the object areas determined in the first determination as a second area (a third determination);

determining an area in which the first area is removed from the image on the transparent platen, as a third area and determining the feature quantity of the image in the third area as a first feature quantity (a fourth determination);

determining an area in which the second and the third area are removed from the image on the transparent platen, as a fourth area and determining the feature quantity of the image in the fourth area as a second feature quantity (a fifth determination); and

determining that, if a difference between the first and the second feature quantity is equal to or smaller than a first threshold value, both of the third and the fourth area are images of the other side of the platen cover and each of the object areas is an image of each of plural documents and, if the difference is greater than the first threshold value, the first area is an area of one document (a sixth determination);

wherein the program code further comprises detecting whether an image of a shadow exists around the periphery of the object area on the image of the transparent platen, the shadow exist if the object is a thick document, and if the shadow is detected, a second threshold value greater than the first threshold value is used in the sixth determination instead of the first threshold value.