Image processing method and device using such method

• US 5,572,603 A
• Filed: 02/21/1995
• Issued: 11/05/1996
• Est. Priority Date: 05/20/1992
• Status: Expired due to Term

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Koike, Kazumasa
• Primary Examiner(s): Mancuso, Joseph
• Application Number:
  US08/391,462
• Time in Patent Office: 623 Days
• Field of Search: 382/22, 382/27, 382/54, 382/18, 382/30, 382/33, 358/456, 358/288, 386/205, 386/209, 386/199, 386/200, 386/217, 386/254, 386/266
• US Class Current: 382/199
• CPC Class Codes: G06T 5/20 using local operators

Abstract

An image processing device in which each pixel data of a gray-scale image, which data is obtained by scanning an original, is converted into a binary image-signal. The device comprises a matrix preparing unit for preparing a 3*3 pixel matrix comprising a focus pixel positioned in the center of the matrix and bordering pixels surrounding the focus pixel, a determining unit for determining whether or not the focus pixel is an edge pixel by comparing an intensity of the focus pixel with intensities of each of three bordering pixels consecutively arranged around the focus pixel, the comparison using the focus-pixel signal and bordering pixel-signals supplied by the matrix preparing unit, and the determining unit also being for outputting a control signal indicating the determined condition of the focus pixel. The device further comprises an enhancing unit for enhancing the focus pixel signal, and a selecting unit for selecting a pixel signal, in accordance with the control signal, from among the focus pixel signal and the enhanced pixel signal.

Claims

1. An image processing method in which each pixel data of a gray-scale image, which data is obtained by means of scanning an original, is determined as either being or not being an edge pixel corresponding to an edge of a picture of the original, the method comprising the steps of:

a) preparing a 3*3 pixel matrix including a focus pixel to be processed, wherein said focus pixel is positioned in the center of the matrix and bordering pixels surround said focus pixel; and

b) determining said focus pixel as either being an edge pixel or not being an edge pixel, by performing a plurality of comparisons of an intensity of said focus pixel with three intensities of respective bordering pixels of a plurality of different sets containing three bordering pixels, the three bordering pixels in each set being arranged consecutively around said focus pixel to form three intensity differences for each one of said plurality of sets, wherein;

1) the three consecutively arranged border pixels in each set include either three consecutive co-linear border pixels, or three non-co-linear pixels including a corner border pixel; and

2) said focus pixel is determined to be an edge pixel when each of the three intensity differences between said focus pixel and each of said three respective bordering pixels in any set of bordering pixels is greater than a predetermined value.

2. The image processing method as claimed in claim 1, wherein said step of determining said focus pixel as either being an edge pixel or not being an edge pixel is performed by a logical circuit which outputs a determination signal in accordance with a logical expression in which all of said three intensity differences of at least one of said plurality of sets is greater than a predetermined threshold value.

3. The image processing method as claimed in claim 1, wherein said focus pixel is determined to be an edge pixel when each of intensity differences between said focus pixel and each of said three bordering pixels is greater than a predetermined first value, said focus pixel being determined to be an unclassifiable pixel when each of intensity differences between said focus pixel and each of said three bordering pixels falls within a range between said first value and a predetermined second value smaller than said first value, and said focus pixel being determined to be a non-edge pixel when said focus pixel is determined neither an edge pixel nor an unclassifiable pixel.

4. An image processing method in which each pixel data of a gray-scale image, which data is obtained by means of scanning an original, is determined as either being or not being an edge pixel corresponding to an edge of a picture of the original, the method comprising the steps of:

a) preparing a 3*3 pixel matrix including a focus pixel to be processed, so that said focus pixel is positioned in the center of the matrix and so that eight bordering pixels surround said focus pixel, said pixel matrix including sets of three bordering pixels, each set of three bordering pixels including two first pixels and a second pixel, one of said two first pixels being positioned at each of two sides of said focus pixel so that said two first pixels and said focus pixel lie along a line, said second pixel being positioned adjacent to said focus pixel and at an equal distance from either of said first pixels; and

b) determining whether or not said focus pixel is an edge pixel, the determining being based on said sets of said second pixel and said two first pixels by comparing an intensity of said second pixel with intensities of each of said first pixels and said focus pixel for each of said sets.

5. The image processing method as claimed in claim 4, wherein said focus pixel is determined to be an edge pixel when each of intensity differences between the intensity of said second pixel and the intensities of each of said first pixels and said focus pixel is greater than a predetermined value.

6. The image processing method as claimed in claim 4, wherein said focus pixel is determined to be an edge pixel when each of intensity differences between said second pixel and each of said first pixels and focus pixel is greater than a first predetermined value, said focus pixel is determined to be an unclassifiable pixel which does not correspond to either an edge pixel or a non-edge pixel when each of intensity differences between said second pixel and each of said first pixels and said focus pixel falls within a range between said first predetermined value and a second predetermined value smaller than said first predetermined value, and said focus pixel is determined to be a non-edge pixel when said focus pixel is determined neither an edge pixel nor an unclassifiable pixel.

7. An image processing method in which each pixel data of a gray-scale image, which data is obtained by means of scanning an original, is converted into a binary image-signal, the image processing device comprising:

a) matrix preparing means for preparing a 3*3 pixel matrix comprising a focus pixel to be processed, so that said focus pixel is positioned in the center of the matrix and bordering pixels surround said focus pixel, said matrix preparing means including means for outputting a focus-pixel signal, and bordering-pixel signals corresponding to each of said bordering pixels;

b) determining means for determining whether or not said focus pixel is an edge pixel by performing a plurality of comparisons of an intensity of said focus pixel with three intensities of respective bordering pixels of each one of a plurality of different sets containing three bordering pixels, the three bordering pixels in each set being consecutively arranged around said focus pixel, wherein;

1) the three consecutively arranged border pixels in each set include either three consecutive co-linear border pixels, or three non-co-linear pixels including a corder border pixel;

the comparison using said focus pixel signal and bordering pixel-signals supplied by said matrix preparing means, and said determining means also being for outputting a control signal indicating the above determined condition of said focus pixel;

2) the comparing includes using said focus-pixel signal and bordering-pixel signals supplied by said matrix preparing means; and

3) said determining means includes means for outputting a control signal indicating the above determined condition of said focus pixel;

c) enhancing means for enhancing said focus-pixel signal supplied by said matrix preparing means by applying a predetermined enhancing process thereto, and for outputting an enhanced pixel signal;

d) selecting means for selecting a selected pixel signal, in accordance with said control signal supplied by said determining means, from among said focus-pixel signal supplied by said matrix preparing means and said enhanced-pixel signal supplied by said enhancing means, wherein;

1) said enhanced pixel signal is output as the selected pixel signal when said control signal indicates that the focus pixel is an edge pixel, and

2) said focus pixel signal is output as the selected pixel signal when said control signal does not indicate that the focus pixel is an edge pixel; and

e) processing means for processing said selected pixel signal supplied by said selecting means by applying a half-tone binarizing process, and for outputting said binary image signal.

8. The image processing device as claimed in claim 7, wherein said determining means comprises means for determining said focus pixel as being an edge pixel when each of intensity differences between said focus pixel and-each of said three bordering pixels is greater than a predetermined value.

9. An image processing device in which each pixel data of a gray-scale image, which data is obtained by scanning an original, is converted into a binary image-signal, the image processing device comprising:

a) matrix preparing means for preparing a 3*3 pixel matrix comprising a focus pixel to be processed, so that said focus pixel is positioned in the center of the matrix and bordering pixels surround said focus pixel, said matrix preparing means including means for outputting a focus-pixel signal, and bordering-pixel signals corresponding to each of said bordering pixels;

b) determining means for determining whether or not said focus pixel is an edge pixel by comparing an intensity of said focus pixel with three intensities of respective bordering pixels arranged in a set containing three bordering pixels, the three bordering pixels in the set being consecutively arranged around said focus pixel, wherein;

1) the three consecutively arranged border pixels in each set include either three consecutive co-linear border pixels, or three non-co-linear pixels including a corner border pixel;

2) the comparing includes using said focus-pixel signal and bordering-pixel signals supplied by said matrix preparing means; and

3) said determining means includes means for outputting a control signal indicating the above determined condition of said focus pixel;

c) smoothing means for smoothing said focus pixel signal supplied by said matrix preparing means by applying a predetermined smoothing process, and for outputting a smoothed pixel signal;

d) selecting means for selecting a selected pixel signal, in accordance with a signal supplied by said determining means, from among said focus-pixel signal supplied by said matrix preparing means and said smoothed pixel signal supplied by said smoothing means, and for outputting the selected pixel signal corresponding to said focus pixel; and

e) processing means for processing said selected pixel signal supplied by said selecting means by applying a half-tone binarizing process thereto, and for outputting said binary image-signal.

10. The image processing device as claimed in claim 9, wherein said determining means comprises means for determining said focus pixel as being an edge pixel when each of intensity differences between said focus pixel and each of said three bordering pixels is greater than a predetermined value.

11. An image processing device in which each pixel data of a gray-scale image data, which data is obtained by scanning an original, is converted into a binary image signal, the image processing device comprising:

a) matrix preparing means for preparing a 3*3 pixel matrix including a focus pixel to be processed, so that said focus pixel is positioned in the center of the matrix and bordering pixels surround said focus pixel, said pixel matrix including sets of three bordering pixels, each set of three bordering pixels including two first pixels and a second pixel, one of said two first pixels being positioned at each of two sides of said focus pixel so that said two first pixels and said focus pixel lie along a line, said second pixel being positioned adjacent to said focus pixel and at equal distance from either of said first pixels, said matrix preparing means including means for outputting a focus-pixel signal and bordering-pixel signals corresponding to each of said bordering pixels;

b) determining means for determining whether or not said focus pixel is an edge pixel the determining being based on said sets of said second pixel and said two first pixels, by comparing an intensity of said second pixel with intensities of each of said first pixels and said focus pixel for each of said sets, and for outputting a control signal indicating the above determined condition of said focus pixel;

c) enhancing means for enhancing said focus-pixel signal supplied by said matrix preparing means by applying a predetermined enhancing process thereto, and for outputting an enhanced pixel signal;

d) selecting means for selecting, in accordance with said control signal supplied by said determining means, a selected pixel signal from among said focus-pixel signal supplied by said matrix preparing means and said enhanced pixel signal supplied by said enhancing means, wherein;

1) said enhanced pixel signal is output as the selected pixel signal when said control signal indicates that the focus pixel is an edge pixel; and

2) said focus-pixel signal is output as the selected pixel signal when said control signal does not indicate that the focus pixel is an edge pixel; and

e) processing means for processing said selected pixel-signal supplied by said selecting means by applying a half-tone binarizing process thereto, and for outputting said binary image signal.

12. The image processing device as claimed in claim 11, wherein said determining means comprises means for determining said focus pixel as being an edge pixel when each of intensity differences between the intensity of said second pixel and intensities of each of said first pixels and focus pixel is greater than a predetermined value.

13. An image processing device in which each pixel data of a gray-scale image, which data is obtained by scanning an original, is converted into a binary image-signal, the image processing device comprising:

a) matrix preparing means for preparing a 3*3 pixel matrix including a focus pixel to be processed, so that said focus pixel is positioned in the center of the matrix and bordering pixels surround said focus pixel, said pixel matrix including sets of three bordering pixels, each set of three bordering pixels including two first pixels and a second pixel, one of said two first pixels being positioned at each of two sides of said focus pixel so that said two first pixels and said focus pixel lie along a line, said second pixel being positioned adjacent to said focus pixel and at equal distance from either of said first pixels, said matrix preparing means including means for outputting a focus-pixel signal, and bordering-pixel signals corresponding to each of said bordering pixels;

b) determining means for determining whether or not said focus pixel is an edge pixel, the determining being based on said sets of said second pixel and said two first pixels, by comparing an intensity of said second pixel with intensities of each of said first pixels and said focus pixel for each of said sets, and for outputting a control signal indicating the above determined condition of said focus pixel;

c) smoothing means for smoothing said focus pixel signal supplied by said matrix preparing means by applying a predetermined smoothing process, and for outputting a smoothed pixel signal;

d) selecting means for selecting a selected pixel signal, in accordance with said control signal supplied by said determining means, from among said focus-pixel signal supplied by said matrix preparing means and said smoothed pixel signal supplied by said smoothing means, and for outputting the selected pixel-signal corresponding to said focus pixel; and

e) processing means for processing said selected pixel signal supplied by said selecting means by applying a half-tone binarizing process thereto, and for outputting said binary image signal.

14. The image processing device as claimed in claim 13, wherein said determining means comprises means for determining said focus pixel as being an edge pixel when each of intensity differences between the intensity of said second pixel and each of the intensities of each of said first pixels and said focus pixel is greater than a predetermined value.

15. An image processing device in which each pixel data of a gray-scale image data, which data is obtained by scanning an original, is converted into a binary image-signal, the image processing device comprising:

a) matrix preparing means for preparing a 3*3 pixel matrix including a focus pixel to be processed, so that said focus pixel is positioned in the center of the matrix and bordering pixels surround said focus pixel, said matrix preparing means including means for outputting a focus-pixel signal, and bordering-pixel signals corresponding to each of said bordering pixels;

b) determining means for determining whether said focus pixel is an edge pixel corresponding to an edge of a picture of said original, a non-edge pixel not corresponding to an edge of the picture of said original, or an unclassifiable pixel which does not correspond either to an edge pixel or to a non-edge pixel, wherein;

1) the determining includes using said focus-pixel signal and said bordering pixel-signals supplied by said matrix preparing means;

2) the determining includes comparing an intensity of said focus pixel with three intensities of respective bordering pixels arranged in a set containing three bordering pixels, the three bordering pixels in the set being consecutively arranged around said focus pixel;

3) the three consecutively arranged border pixels in each set include either three consecutive co-linear border pixels, or three non-co-linear pixels including a corner border pixel; and

4) said determining means includes means for outputting a control signal indicating the above determined condition of said focus pixel;

c) enhancing means for enhancing said focus-pixel signal supplied by said matrix preparing means by applying a predetermined enhancing process, and for outputting an enhanced pixel signal;

d) smoothing means for smoothing said focus pixel signal supplied by said matrix preparing means by applying a predetermined enhancing process thereto, and for outputting a smoothed pixel signal;

e) selecting means for selecting, in accordance with said control signal supplied by said determining means, a selected pixel signal from among said focus-pixel signal supplied by said matrix preparing means, said enhanced pixel signal supplied by said enhancing means, and said smoothed pixel signal supplied by said smoothing means, wherein;

1) said enhanced pixel signal is output as the selected pixel signal when said control signal indicates said focus pixel is an edge pixel;

2) said smoothed pixel signal is output as the selected pixel signal when said control signal indicates that said focus pixel is a pixel other than an edge pixel and non-edge pixel; and

f) processing means for processing said selected pixel signal supplied by said selecting means by applying a half-tone binarizing process thereto, and for outputting said binary image signal.

16. The image processing device as claimed in claim 15, wherein said determining means comprises means for determining said focus pixel as being an edge pixel when each of intensity differences between said focus pixel and each of said three bordering pixels is greater than a predetermined first intensity value, said focus pixel being determined as an unclassifiable pixel when each of intensity differences between said focus pixel and each of said three bordering pixels falls within a range between said first intensity value and a predetermined second intensity value smaller than said first intensity value, and said focus pixel being determined as a non-edge pixel when said focus pixel is determined neither to be an edge pixel nor to be an unclassifiable pixel.

17. An image processing device in which each pixel data of a gray-scale image, which data is obtained by scanning an original, is converted into a binary image-signal, the image processing device comprising:

a) matrix preparing means for preparing a 3*3 pixel matrix comprising a focus pixel to be processed, so that said focus pixel is positioned in the center of the matrix and bordering pixels surround said focus pixel, said pixel matrix including sets of three bordering pixels, each set of three bordering pixels including two first pixels and a second pixel, one of said two first pixels being positioned at each of two sides of said focus pixel so that said two first pixels and said focus pixel lie along a line, said second pixel being positioned adjacent to said focus pixel and at equal distance from either of said first pixels, said matrix preparing means including means for outputting a focus-pixel signal, and bordering-pixel signals corresponding to each of said bordering pixels;

b) determining means for determining whether said focus pixel is an edge pixel corresponding to an edge of a picture of said original, a non-edge pixel not corresponding to an edge of the picture of said original, or an unclassifiable pixel which corresponds to neither an edge pixel nor a non-edge pixel, wherein;

1) the determining includes using said focus-pixel signal and bordering pixel-signals supplied by said matrix preparing means;

2) the determining is based on said sets of said second pixel and said two first pixels, and includes comparing an intensity of said second pixel with intensities of each of said first pixels and said focus pixel for each set; and

3) the determining means includes means for outputting a control signal indicating the above determined condition of said focus pixel;

c) enhancing means for enhancing said focus-pixel signal supplied by said matrix preparing means by applying a predetermined enhancing process thereto, and for outputting an enhanced pixel signal;

d) smoothing means for smoothing said focus-pixel signal supplied by said matrix preparing means by applying a predetermined smoothing process thereto, and for outputting a smoothed pixel signal;

e) selecting means for selecting a selected pixel signal, in accordance with said control signal supplied by said determining means, from among said focus-pixel signal supplied by said matrix preparing means, said enhanced pixel signal supplied by said enhancing means and said smoothed pixel signal supplied by said smoothing means, wherein;

1) said enhanced pixel signal is output as a selected pixel signal when said control signal indicates that said focus pixel is an edge pixel;

2) said smoothed pixel signal is output as a selected signal when said control signal indicates that said focus pixel is a non-edge pixel; and

f) processing means for processing said selected pixel signal supplied by said selecting means by applying a half-tone binarizing process, and for outputting said binary image signal.

18. The image processing device as claimed in claim 17, wherein said determining means comprises means for determining said focus pixel as being an edge pixel when each of intensity differences between the intensity of said second pixel and each of the intensities of each of first pixels and said focus pixel is greater than a predetermined first value, said focus pixel being determined as an unclassifiable pixel when each of intensity differences between the intensity of said second pixel and the intensities each of said first pixels and said focus pixel falls within a range between said first value and a predetermined second value smaller than said first value, and said focus pixel being determined as a non-edge pixel when said focus pixel is neither an edge pixel nor an unclassifiable pixel.