Edge enhancement preprocessing with image region determining function

• US 6,757,427 B1
• Filed: 08/21/2000
• Issued: 06/29/2004
• Est. Priority Date: 08/24/1999
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Hongu, Takahiro
• Primary Examiner(s): Mehta, Bhavesh M.
• Assistant Examiner(s): Hung, Yubin
• Application Number:
  US09/642,094
• Time in Patent Office: 1,408 Days
• Field of Search: 382/173, 382/176, 382/177, 382/180, 382/185, 382/199, 382/200, 382/266, 382/268, 382/162-166, 358/538, 358/453, 358/464, 358/462
• US Class Current: 382/164
• CPC Class Codes: H04N 1/40062 Discrimination between different image types, e.g. two-tone, continuous tone

Abstract

An image processing apparatus includes an edge processing section, an region data producing section, and a region determining section. The edge processing section enhances an edge portion of a first region of an image in units of picture elements to produce an enhanced image. The image includes the first region and a second region which are mixed, and picture elements of the image are expressed to as RGB data. The region data producing section divides the enhanced image into regions to output region data indicative of each of the regions, variance data of each of the regions and contour edge data indicative of a contour of each of the regions. The region determining section determines the first region in the enhanced image based on the region data, the variance data and the contour edge data.

Claims

1. An image processing apparatus comprising:

an edge processing section which enhances an edge portion of a first region of an image in units of picture elements to produce an enhanced image, wherein said image includes said first region and a second region which are mixed, and picture elements of said image are expressed to as RGB data;

a region data producing section which divides said enhanced image into regions to output region data indicative of each of said regions, variance data of each of said regions and contour edge data indicative of a contour of each of said regions;

a region determining section which determines said first region in said enhanced image based on said region data, said variance data and said contour edge data;

wherein said edge processing section selectively sets a picture element value of each of picture elements of said image as a concerned picture element to that of one of neighbor picture elements of the picture element in units of picture elements of said image, to produce said enhanced image;

wherein said edge processing section carries out an enhancing process to set said picture element value of said concerned picture element to said picture element value of a first one of said neighbor picture elements when said concerned picture element has a middle color between said first neighbor picture element and a second one of said neighbor picture elements in a direction opposite to a direction of said first neighbor picture element with respect to said concerned picture element;

wherein said edge processing section carries out said enhancing process to set said picture element value of said concerned picture element to said picture element value of said first neighbor picture element, when said concerned picture element has said middle color, and when a first color difference between said concerned picture element and said first neighbor picture element is smaller than a second color difference between said concerned picture element and said second neighbor picture element, and to set said picture element value of said concerned picture element to said picture element value of said second neighbor picture element, when said concerned picture element has said middle color, and when said first color difference is equal to or larger than said second color difference between said concerned picture element and said second neighbor picture element; and

wherein said color difference between said first and second neighbor picture elements is the largest among said color differences in the other opposing directions.

2. The image processing apparatus according to claim 1, wherein said edge processing section carries out said enhancing process, when a color difference between said first and second neighbor picture elements is equal to or larger than a first predetermined value.

3. The image processing apparatus according to claim 1, wherein said edge processing section carries out said enhancing process, when a ratio of a third color difference between picture elements outside of said first and second neighbor picture elements in said opposing directions to the color difference between said first and second neighbor picture elements is equal to or larger than a second predetermined value.

4. An image processing method comprising:

enhancing an edge portion of a first region of an image in units of picture elements to produce an enhanced image, wherein said image includes said first region and a second region which are mixed, and picture elements of said image are expressed to as RGB data;

dividing said enhanced image into regions to output region data indicative of each of said regions, variance data of each of said regions and contour edge data indicative of a contour of each of said regions;

determining said first region in said enhanced image based on said region data, said variance data and said contour edge data;

wherein said enhancing includes;

selectively setting a picture element value of each of picture elements of said image as a concerned picture element to that of one of neighbor picture elements of the picture element in units of picture elements of said image, to produce said enhanced image;

wherein said enhancing includes;

carrying out an enhancing process to set said picture element value of said concerned picture element to said picture element value of a first one of said neighbor picture elements when said concerned picture element has a middle color between said first neighbor picture element and a second one of said neighbor picture elements in a direction opposite to a direction of said first neighbor picture element with respect to said concerned picture element;

wherein said enhancing includes;

carrying out said enhancing process to set said picture element value of said concerned picture element to said picture element value of said first neighbor picture element, when said concerned picture element has said middle color, and when a first color difference between said concerned picture element and said first neighbor picture element is smaller than a second color difference between said concerned picture element and said second neighbor picture element, and to set said picture element value of said concerned picture element to said picture element value of said second neighbor picture element, when said concerned picture element has said middle color, and when said first color difference is equal to or larger than said second color difference between said concerned picture element and said second neighbor picture element; and

wherein said color difference between said first and second neighbor picture elements is the largest among said color differences in the other opposing directions.

5. The image processing method according to claim 4 wherein said enhancing includes:

carrying out said enhancing process, when a color difference between said first and second neighbor picture elements is equal to or larger than a first predetermined value.

6. The image processing method according to claim 4 wherein said enhancing includes:

carries out said enhancing process, when a ratio of a third color difference between picture elements outside of said first and second neighbor picture elements in said opposing directions to the color difference between said first and second neighbor picture elements is equal to or larger than a second predetermined value.

7. A recording medium in which a program is stored for an image processing method, wherein said method comprises:

enhancing an edge portion of a first region of an image in units of picture elements to produce an enhanced image, wherein said image includes said first region and a second region which are mixed, and picture elements of said image are expressed to as RGB data;

dividing said enhanced image into regions to output region data indicative of each of said regions, variance data of each of said regions and contour edge data indicative of a contour of each of said regions;

determining said first region in said enhanced image based on said region data, said variance data and said contour edge data;

wherein said enhancing includes;

selectively setting a picture element value of each of picture elements of said image as a concerned picture element to that of one of neighbor picture elements of the picture element in units of picture elements of said image, to produce said enhanced image;

wherein said enhancing includes;

carrying out an enhancing process to set said picture element value of said concerned picture element to said picture element value of a first one of said neighbor picture elements when said concerned picture element has a middle color between said first neighbor picture element and a second one of said neighbor picture elements in a direction opposite to a direction of said first neighbor picture element with respect to said concerned picture element;

wherein said enhancing includes;

carrying out said enhancing process to set said picture element value of said concerned picture element to said picture element value of said first neighbor picture element, when said concerned picture element has said middle color, and when a first color difference between said concerned picture element and said first neighbor picture element is smaller than a second color difference between said concerned picture element and said second neighbor picture element, and to set said picture element value of said concerned picture element to said picture element value of said second neighbor picture element, when said concerned picture element has said middle color, and when said first color difference is equal to or larger than said second color difference between said concerned picture element and said second neighbor picture element; and

wherein said color difference between said first and second neighbor picture elements is the largest among said color differences in the other opposing directions.

8. The recording medium according to claim 7, wherein said enhancing includes:

carrying out said enhancing process, when a color difference between said first and second neighbor picture elements is equal to or larger than a first predetermined value.

9. The recording medium according to claim 7, wherein said enhancing includes:

carries out said enhancing process, when a ratio of the color difference between picture elements outside of said first and second neighbor picture elements in said opposing directions to a third color difference between said first and second neighbor picture elements is equal to or larger than a second predetermined value.