Image processing apparatus and image processing program product for discriminating dot region in image

• US 7,792,364 B2
• Filed: 12/09/2003
• Issued: 09/07/2010
• Est. Priority Date: 08/12/2003
• Status: Active Grant

• Current Assignee: Konica Minolta Business Technologies Incorporated (Konica Minolta Inc.)
• Original Assignee: Konica Minolta Business Technologies Incorporated (Konica Minolta Inc.)
• Inventors: Ishiguro, Kazuhiro
• Primary Examiner(s): Bella; Matthew C
• Assistant Examiner(s): RAHMJOO, MANUCHER
• Application Number:
  US10/730,122
• Publication Number:
  US 20050036687A1
• Time in Patent Office: 2,464 Days
• Field of Search: 382/194, 382/195, 382/203, 382/218
• US Class Current: 382/194
• CPC Class Codes: G06V 30/413 Classification of content, e.g. text, photographs or tables
• CPC Class Codes: H04N 1/40062 Discrimination between different image types, e.g. two-tone, continuous tone

Abstract

To accurately discriminate a dot region within an image, the image processing apparatus includes first through fourth isolated dot discriminating portions each judging, for each of a plurality of pixels included in the image, whether the pixel corresponds to a center pixel of an isolated dot, an isolated dot size determining portion detecting an isolated dot size, a dot region discriminating portion judging whether a target pixel is included in a dot region based on a position of the pixel judged as being the center pixel of the isolated dot, and a dot region determining portion determining the dot region based on a position of the target pixel judged as being included in the dot region and the detected isolated dot size.

Claims

1. An image processing apparatus comprising:

an isolated dot discriminating portion judging, for each pixel of a plurality of pixels included in an image, whether the pixel corresponds to a center pixel of an isolated dot;

a size detector detecting an isolated dot size;

a dot region discriminating portion judging whether a target pixel is included in a dot region based on a position of said pixel judged as being the center pixel of the isolated dot; and

a dot region determining portion determining a dot region based on a position of said target pixel judged as being included in the dot region and said isolated dot size detected,

wherein said dot region discriminating portion includes

a counter counting the number of center pixels of isolated dots existing within a prescribed range from a process-target pixel, and

a comparator comparing said counted number of the center pixels of the isolated dots with a predetermined threshold value.

2. The image processing apparatus according to claim 1, wherein said counter counts the number of the center pixels of the isolated dots of all sizes regardless of the isolated dot sizes.

3. The image processing apparatus according to claim 1, wherein

said counter counts the number of the center pixels of the isolated dots separately for each isolated dot size, and

said comparator compares the number of the center pixels of the isolated dots of the isolated dot size having been determined to exist in a greatest number with said threshold value.

4. The image processing apparatus according to claim 1, wherein

said counter counts the number of the center pixels of the isolated dots separately for each isolated dot size, and

said dot region discriminating portion judges that said process-target pixel is not included in a dot region when said comparator determines that the number of the center pixels of the isolated dots of the isolated dot size existing in a greatest number and the number of the center pixels of the isolated dots of the isolated dot size existing in a next greatest number both exceed said threshold value.

5. The image processing apparatus according to claim 1, wherein

said counter counts the number of the center pixels of the isolated dots separately for each isolated dot size, and

said dot region discriminating portion judges that said process-target pixel is included in a dot region when a sum of the number of the center pixels of the isolated dots of a first isolated dot size existing in a greatest number and the number of the center pixels of the isolated dots of a second isolated dot size different from said first isolated dot size exceeds said threshold value even if the number of the center pixels of the isolated dots of said first isolated dot size does not exceed said threshold value.

6. The image processing apparatus according to claim 1, wherein said dot region determining portion includes

a tentative region determining portion determining a region within said prescribed range as a tentative region based on positions of the pixels judged as being included in the dot region, and

a correcting portion correcting said determined tentative region based on said detected isolated dot size.

7. The image processing apparatus according to claim 6, wherein said correcting portion includes an expanding portion expanding said tentative region by the number of pixels of not greater than half said detected isolated dot size.

8. The image processing apparatus according to claim 1, wherein said isolated dot discriminating portion includes

a plurality of calculators, each using a filter having sensitivity corresponding to an isolated dot size different from each other to calculate an evaluation value corresponding to the relevant isolated dot size for each process-target pixel, and

a comparator comparing evaluation values calculated by said plurality of calculators with prescribed threshold values.

9. The image processing apparatus according to claim 1, further comprising a processor performing prescribed processing on the image, said processor changing a level of said prescribed processing to be performed on said determined dot region in accordance with said detected isolated dot size.

10. The image processing apparatus according to claim 9, wherein said prescribed processing is smoothing.

11. The image processing apparatus according to claim 9, wherein said prescribed processing is edge enhancement.

12. The image processing apparatus according to claim 9, wherein said level includes a level where no processing is performed.

13. An image processing apparatus comprising:

an isolated dot discriminating portion judging, for each pixel of a plurality of pixels included in an image, whether the pixel corresponds to a center pixel of an isolated dot;

a size detector detecting an isolated dot size;

a dot region discriminating portion judging whether a target pixel is included in a dot region based on a position of said pixel judged as being the center pixel of the isolated dot; and

a dot region determining portion determining a dot region based on a position of said target pixel judged as being included in the dot region and said isolated dot size detected, wherein

said dot region discriminating portion judges that a process-target pixel is included in a dot region when said process-target pixel is included in a smallest rectangular region including center pixels of isolated dots, and

said dot region determining portion determines the dot region to include said process-target pixel and peripheral pixels within a range of the number of pixels of not greater than half said detected isolated dot size from said process-target pixel.