Image processing apparatus, image processing method, and program and storage medium therefor

• US 7,376,267 B2
• Filed: 02/26/2007
• Issued: 05/20/2008
• Est. Priority Date: 07/12/2000
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Toda, Yukari
• Primary Examiner(s): Alavi; Amir
• Application Number:
  US11/678,914
• Publication Number:
  US 20070154091A1
• Time in Patent Office: 449 Days
• Field of Search: 382/162, 382/164, 382/165, 382/166, 382/232, 382/233, 382/276, 382/277, 345/589, 345/600, 345/603, 358/2.1, 358/3.21, 358/504, 358/515, 358/523, 358/530
• US Class Current: 382/166
• CPC Class Codes: G06T 2207/10008 from scanner, fax or copier
• CPC Class Codes: G06T 2207/10024 Color image
• CPC Class Codes: G06T 2207/30176 Document
• CPC Class Codes: G06T 7/11 Region-based segmentation
• 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
• CPC Class Codes: H04N 1/41 Bandwidth or redundancy reduction by scanning H04N1/17 ; methods or arrangements for coding, decoding, compressing or decompressing digital video signals H04N19/00
• CPC Class Codes: H04N 19/12 Selection from among a plurality of transforms or standards, e.g. selection between discrete cosine transform [DCT] and sub-band transform or selection between H.263 and H.264
• CPC Class Codes: H04N 19/136 Incoming video signal characteristics or properties
• CPC Class Codes: H04N 19/17 the unit being an image region, e.g. an object
• CPC Class Codes: H04N 19/60 using transform coding
• CPC Class Codes: H04N 19/90 using coding techniques not provided for in groups H04N19/10-H04N19/85, e.g. fractals

Abstract

In an image processing apparatus, a histogram calculation unit calculates a histogram that is consonant with an input image, a binary threshold value calculation unit calculates a binary threshold value, based on the histogram, with which a predetermined area in the input image is blurred, and a binarizing unit binarizes the input image using the binary threshold value. In addition, a calculation unit calculates the color of the predetermined area of the input image based on the results obtained by the binarizing unit.

Claims

1. An image processing apparatus comprising:

binarization means for binarizing color image data obtained by an image reading process into binary image data and outputting the binary image data;

detection means for detecting a symbol area including a plurality of symbols, based on the binary image data binarized by said binarization means;

symbol cutting means for cutting the plurality of symbols one by one from the symbol area detected by said detection means, based on the binary image data, and obtaining symbol cutting information indicating each of the plurality of symbols;

color allocation means for generating image data corresponding to the symbol area detected by said detection means such that in the image data the plurality of symbols cut from the symbol area are allocated respective representative colors, based on the symbol cutting information obtained by said symbol cutting means and the color image data corresponding to the symbol area; and

compression means for compressing the image data corresponding to the detected symbol area generated by said color allocation means in different compression methods in accordance with the number of the representative colors allocated to the plurality of symbols.

2. An apparatus according to claim 1, wherein said color allocation means select, for each of the plurality of symbols, a color which occupies the largest number of pixels forming the symbol as the representative color for the symbol.

3. An apparatus according to claim 2, wherein said compression means compress the image data corresponding to the symbol area in MMR compression method if the number of the representative colors is one, in ZIP compression method if the number of the representative colors is greater than one and smaller than a predetermined number S, or in JPEG compression method if the number of the representative colors is equal to or greater than S.

4. An image processing method comprising:

a binarization step of binarizing color image data obtained from an image into binary image data and outputting the binary image data;

a detection step of detecting a symbol area including a plurality of symbols, based on the binary image data binarized in said binarization step;

a symbol cutting step of cutting the plurality of symbols one by one from the symbol area detected in said detection step, based on the binary image data, and obtaining symbol cutting information indicating each of the plurality of symbols;

a color allocation step of generating image data corresponding to the symbol area detected in said detection step such that in the image data the plurality of symbols cut from the symbol area are allocated respective representative colors, based on the symbol cutting information obtained in said symbol cutting step and the color image data corresponding to the symbol area; and

a compression step of compressing the image data corresponding to the detected symbol area generated in said color allocation step in different compression methods in accordance with the number of the representative colors allocated to the plurality of symbols.

5. A computer program stored in a computer-readable storage medium, the program causing a computer to execute an image processing method comprising:

a binarization step of binarizing color image data obtained from an image into binary image data and outputting the binary image data;

a detection step of detecting a symbol area including a plurality of symbols, based on the binary image data binarized in said binarization step;

a symbol cutting step of cutting the plurality of symbols one by one from the symbol area detected in said detection step, based on the binary image data, and obtaining symbol cutting information indicating each of the plurality of symbols;

a color allocation step of generating image data corresponding to the symbol area detected in said detection step such that in the image data the plurality of symbols cut from the symbol area are allocated respective representative colors, based on the symbol cutting information obtained in said symbol cutting step and the color image data corresponding to the symbol area; and

a compression step of compressing the image data corresponding to the detected symbol area generated in said color allocation step in different compression methods in accordance with the number of the representative colors allocated to the plurality of symbols.

6. A computer-readable storage medium that stores a computer program causing a computer to execute an image processing method comprising:

a binarization step of binarizing color image data obtained from an image into binary image data and outputting the binary image data;

a detection step of detecting a symbol area including a plurality of symbols, based on the binary image data binarized in said binarization step;

a symbol cutting step of cutting the plurality of symbols one by one from the symbol area detected in said detection step, based on the binary image data, and obtaining symbol cutting information indicating each of the plurality of symbols;

a color allocation step of generating image data corresponding to the symbol area detected in said detection step such that in the image data the plurality of symbols cut from the symbol area are allocated respective representative colors, based on the symbol cutting information obtained in said symbol cutting step and the color image data corresponding to the symbol area; and

a compression step of compressing the image data corresponding to the detected symbol area generated in said color allocation step in different compression methods in accordance with the number of the representative colors allocated to the plurality of symbols.