Image processing method and apparatus which iteratively divides image data into sub-regions

• US 6,282,314 B1
• Filed: 09/06/1995
• Issued: 08/28/2001
• Est. Priority Date: 09/08/1994
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Mori, Hiroshi, Maeda, Mitsuru, Yamada, Osamu, Makita, Takeshi, Sugiura, Susumu
• Primary Examiner(s): Patel, Jay
• Application Number:
  US08/524,409
• Time in Patent Office: 2,183 Days
• Field of Search: 358/434, 358/262.1, 358/443, 358/455-458, 358/453, 358/401, 358/500, 358/538, 382/240, 382/302, 382/307, 382/100, 382/171, 382/172, 382/173, 382/175-180, 348/588
• US Class Current: 382/173
• CPC Class Codes: G06V 30/10 Character recognition
• CPC Class Codes: G06V 30/162 Quantising the image signal
• CPC Class Codes: G06V 30/413 Classification of content, e.g. text, photographs or tables
• CPC Class Codes: H04N 1/403 Discrimination between the two tones in the picture signal of a two-tone original

Abstract

An object of the invention is to convert multivalue image data to data in a format which can be easily handled. For such an object, the multivalue image data of each pixel is inputted and an image expressed by the multivalue image data is converted to data which is hierarchically structured to a plurality of layers.

Claims

1. An image processing method for processing multivalue image data representing an image that includes a first portion and a second portion, comprising the steps of:

inputting the multivalue image data; and

sequentially converting the image represented by said multivalue image data into hierarchically structured data,

wherein said converting step includes

a step of dividing the image into a plurality of partial areas in accordance with image data corresponding to the image, the plurality of partial areas including the first portion and the second portion, said second portion having a first subportion and a second subportion,

a step of separating a sub-Partial area from said first subportion by using a threshold determined by multivalue image data included in said first subportion, and

a step of separating a sub-partial area from said second subportion by using a threshold determined by multivalue image data included in said second subportion.

2. A method according to claim 1, further comprising the step of compressing said hierarchically structured data.

3. A method according to claim 1, further comprising the step of communicating said hierarchically structured data with an outside media.

4. A method according to claim 1, wherein said hierarchically structured data has image data for character recognition, image data for display/print, and a plurality of code data groups for retrieval.

5. A method according to claim 1, wherein said conversion is executed by discriminating the kind of image area on the basis of different discrimination parameters step by step.

6. A method according to claim 1, wherein the plurality of layers are divided to form the plurality of partial areas in accordance with different kinds of partial image areas of the image represented by said multivalue image data.

7. A method according to claim 6, wherein the plurality of partial areas include a character portion, an image portion and a table portion.

8. A method according to claim 7, wherein non-character portions of the plurality of partial areas are further divided in said step of dividing the partial areas into the plurality of sub-partial areas.

9. An image processing method for processing image data representing an image that includes a first portion and a second portion, comprising the steps of:

outputting the image data representing the image;

determining a first threshold based on the image data corresponding to said image;

binarizing the image data by comparing the image data with the first threshold and generating resultant first binary data;

dividing the image into a plurality of partial areas in accordance with the first binary data, the plurality of partial areas including the first portion and the second portion, the second portion including a first subportion and a second subportion;

determining a second threshold in the second subportion of said second portion based on image data included in said second subportion;

binarizing the image data in the second subportion by comparing the image data with the second threshold and generating resultant second binary data; and

dividing the second subportion into sub-partial areas in accordance with the second binary data.

10. A method according to claim 9, wherein said partial area is a character area or a non-character area.

11. A method according to claim 9, further comprising the step of recognizing characters in said partial areas or sub-partial areas.

12. A method according to claim 9, further comprising the step of performing a halftone processing to a halftone area in said sub-partial areas.

13. A method according to claim 12, further comprising the step of compressing the image data and storing into a file.

14. A medium which stores computer programs for use with an image processing for processing multivalue image data representing an image that includes a first portion and a second portion, comprising the steps of:

causing a computer to output image data representing an image;

causing the computer to determine a first threshold based on the image data corresponding to said image;

causing the computer to binarize the image data by comparing the image data with the first threshold and to generate first binary data;

causing the computer to divide the image into a plurality of partial areas in accordance with the first binary data, the plurality of areas including the first portion and the second portion, the second portion including a first subportion and a second subportion;

causing the computer to determine a second threshold in the second subportion of said second portion based on image data included in said second subportion;

causing the computer to binarize the image data in the second subportion by comparing the image data with the second threshold and to generate second binary data; and

causing the computer to divide the second subportion into sub-partial areas in accordance with the second binary data.