Table recognition apparatus

• US 5,708,730 A
• Filed: 06/07/1995
• Issued: 01/13/1998
• Est. Priority Date: 10/27/1992
• Status: Expired due to Term

• Current Assignee: Fuji Xerox Company Limited (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Xerox Company Limited (Fujifilm Holdings Corporation)
• Inventors: Itonori, Katsuhiko
• Primary Examiner(s): Mancuso, Joseph
• Assistant Examiner(s): Prikockis, Larry J.
• Application Number:
  US08/479,974
• Time in Patent Office: 951 Days
• Field of Search: 382/176, 382/177, 382/178, 382/173, 382/174, 382/175, 382/179, 382/180, 382/294, 382/295, 358/462, 358/453, 395/148, 395/149, 395/770, 395/771
• US Class Current: 382/177
• CPC Class Codes: G06V 30/412 Layout analysis of documents structured with printed lines or input boxes, e.g. business forms or tables

Abstract

A table recognition apparatus for recognizing a table image wherein coexist characters and ruled lines. The apparatus comprises a character/ruled line separating part for separating characters from ruled lines in the table image; a character block extracting part for extracting character blocks from the character image separated by the character/ruled line separating part; and a character block extending part for extending the character blocks extracted by the character block extracting part in such a manner that the edges of the character blocks are aligned according to the positional relations between the blocks.

Claims

1. A table recognition apparatus for recognizing a table image having both a character image and a ruled line image, said table recognition apparatus comprising:

image separating means for separating characters from ruled lines in said table image;

means for acquiring a rectangular area containing a character in the character image;

means for producing a threshold from the dimensions of said acquired rectangular area;

character block extracting means for using said threshold to extract character blocks from the character image separated by said image separating means;

first character block extending means for extending each of said character blocks up to the nearest one of the ruled lines;

means for computing a horizontal and a vertical distribution of character blocks to keep each extended character block from overlapping with other ones of the character blocks;

second character block extending means for further extending the extended character blocks to align the edges of the extended character blocks;

row extracting means for extracting rows of said table image based on the distance between the extended character blocks; and

column extracting means for extracting columns of said table image based on the distance between the extended character blocks.

2. A table recognition apparatus for recognizing a table image having both a character image and a ruled line image, said table recognition apparatus comprising:

image separating means for separating characters from ruled lines in said table image;

character block extracting means for extracting character blocks from the character image separated by said image separating means;

rectangular frame extracting means for extracting a rectangle composed of ruled lines, from the ruled line image separated by said image separating means;

means for converting the extracted ruled lines into a plurality of horizontal and vertical vectors;

means for comparing said horizontal and vertical vectors to a threshold angle;

component frame extracting means for extracting as a component frame a rectangular frame including at most one character block;

means for computing a horizontal and vertical distribution of character blocks

first character block extending means for using said computed horizontal and vertical distribution of character blocks to extend a target character block up to the nearest one of the ruled lines;

second character block extending means for further extending the extended character blocks to align the edges of the extended character blocks;

row extracting means for extracting rows of said table image based on the distance between the extended character blocks; and

column extracting means for extracting columns of said table image based on the distance between the extended character blocks.

3. A table recognition apparatus for recognizing a table image having both a character image and a ruled line image, said table recognition apparatus comprising:

image separating means for separating characters from ruled lines in said table image;

first character block extending means for extending each of said character blocks up to the nearest one of the ruled lines;

means for computing a horizontal and a vertical distribution of character blocks to keep each extended character block from overlapping with other ones of the character blocks;

second character block extending means for further extending the extended character blocks to align the edges of the extended character blocks;

character block normalizing means for normalizing each character block based on the distance between the extended character blocks;

character block interpolating means for detecting a virtual character block that overlaps the character blocks normalized by said character block normalizing means;

row extracting means for extracting rows based on the distance between the character blocks interpolated by said character block interpolating means; and

column extracting means for extracting columns based on the distance between the character blocks interpolated by said character block interpolating means.