Image reading apparatus

• US 6,466,340 B1
• Filed: 02/25/1999
• Issued: 10/15/2002
• Est. Priority Date: 03/02/1998
• Status: Expired due to Fees

• Current Assignee: Konica Corporation (Konica Minolta Inc.)
• Original Assignee: Konica Corporation (Konica Minolta Inc.)
• Inventors: Washio, Koji
• Primary Examiner(s): Lee, Cheukfan
• Application Number:
  US09/257,702
• Time in Patent Office: 1,328 Days
• Field of Search: 358/488, 358/474, 358/452, 358/453, 358/448, 358/494, 358/497, 382/289, 382/296
• US Class Current: 358/488
• CPC Class Codes: G06V 30/1478 of characters or characters lines
• CPC Class Codes: H04N 1/3878 Skew detection or correction

Abstract

An image reading apparatus includes: an image reading device for reading an image in a reading area including an inside and an outside of an original document area to obtain image data; a memory for storing the image data obtained by the image reading device; an edge detector for detecting a plurality of edges in the original document area according to the image data obtained by the image reading device; a calculator for calculating an inclination of an original document on the basis of the plurality of edges detected by the edge detector; and a correcting device for correcting the inclination of the original document on the basis of the inclination calculated by the calculator with respect to at least the image data in the original document area among the image data stored in the memory.

Claims

1. An image reading apparatus comprising:

(a) image reading means for reading an image in a reading area including an inside and an outside of an original document area to obtain image data;

(b) a memory for storing the image data obtained by the image reading means;

(c) edge detecting means for detecting a plurality of edges in the original document area according to the image data obtained by the image reading means,

wherein said detecting means detects a first difference in values on coordinates between two adjacent edges of the plurality of edges, determines an inclination of the two adjacent edges based on the first difference, judges whether the inclination has an inclination angle of less than 45°

, and then selects edges having the inclination angle of less than 45°

by applying a first template matching to the judgment result, and

wherein said detecting means detects a second difference in values on coordinates between two adjacent first differences, determines a singular edge point which does not designate the edge of the original document by applying a second template matching different from the first template matching, and then eliminates the singular edge point from the selected edges having the inclination angle of less than 45°

;

(d) calculating means for calculating an inclination angle of an original document based on the selected edges; and

(e) correcting means for correcting the inclination angle of the original document based on the inclination angle calculated by the calculating means with respect to at least the image data in the original document area among the image data stored in the memory.

2. The image reading apparatus of claim 1, further comprising:

a document platen on which the original document is placed;

a document platen cover having an optical characteristic different from white for covering the document platen;

scanning means for optically scanning the reading area including the inside and outside of the original document area through the document platen; and

an image sensor for conducting photoelectric conversion of light reflected from the reading area, to thereby read the image in said reading area and obtain the image data.

3. The image reading apparatus of claim 1, further comprising converting means for converting image data outside the original document area to have a predetermined density.