Apparatus for clearing an image and method thereof

• US 7,936,941 B2
• Filed: 10/04/2005
• Issued: 05/03/2011
• Est. Priority Date: 10/08/2004
• Status: Expired due to Fees

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Hizume, Taro, Sumiya, Kazunori, Sano, Toshiyuki, Yata, Manabu
• Primary Examiner(s): Mehta; Bhavesh M
• Assistant Examiner(s): Thirugnanam; Gandhi
• Application Number:
  US11/576,726
• Publication Number:
  US 20080199101A1
• Time in Patent Office: 2,037 Days
• Field of Search: 382260-264, 382/266, 382270-272, 382/275
• US Class Current: 382/266
• CPC Class Codes: G06T 2207/20012 Locally adaptive
• CPC Class Codes: G06T 2207/20192 Edge enhancement; Edge preservation
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: G06T 5/70 Denoising; Smoothing
• CPC Class Codes: G06T 5/73 Deblurring; Sharpening
• CPC Class Codes: H04N 1/4092 Edge or detail enhancement

Abstract

An object of the present invention is to provide an image processing apparatus capable of obtaining a sharp image having less noise, comprising: a horizontal edge strength calculating unit 22 for calculating an edge strength along a horizontal direction of a concerned pixel; and a prefilter 24 for carrying out a filter processing based on the horizontal edge strength, and performing noise reduction and edge enhancement, a vertical edge strength calculating unit 23 for calculating an edge strength along a vertical direction of the concerned pixel; and a prefilter 25 for carrying out a filter processing based on the vertical edge strength, and performing noise reduction and edge enhancement, thereby enabling to sharpen image data in the vicinity of the concerned pixel respectively along horizontal and vertical directions, and obtain an image having less noises as well as sharp for edge directions.

Claims

1. An image processing apparatus, comprising:

image data inputting means for inputting image data;

edge strength calculating means comprising a processor operable to execute program modules for calculating an edge strength along a specific direction based on a difference of level between a concerned pixel of said inputted image data and a pixel disposed in vicinity of said concerned pixel;

filter processing means comprising a processor operable to execute program modules for determining a filter based on said edge strength along said specific direction calculated by said edge strength calculating means, carrying out filter processing on pixel data, and selectively performing noise reduction and edge enhancement by way of said filter;

edge enhancement signal generating means for generating an edge enhancement signal based on said pixel data on which said filter processing has been carried out; and

image correcting means for correcting said inputted image data based on said edge enhancement signal, wherein

said filter processing means is operative to calculate a preliminary value by multiplying said edge strength along said specific direction by a gradient coefficient and adding an image quality adjusting value to be used for adjusting image quality to the multiplication result, to compare said preliminary value with a predetermined upper limit and a predetermined lower limit, to determine, as a weighting coefficient, said upper limit if said preliminary value is greater than said upper limit, said lower limit if said preliminary value is less than said lower limit, and said preliminary value if said preliminary value is not greater than said upper limit nor less than said lower limit, and to selectively perform noise reduction and edge enhancement by carrying out weighted addition using said weighting coefficient on data of said concerned pixel.

4. An image processing apparatus as set forth in claim 1, in which

said filter processing unit is operative to carry out said weight addition by adding a product of a difference value of data between said concerned pixel and an average value of pixels respectively disposed in the vicinity of said concerned pixel, and said weight coefficient, to an average value of data of said pixels disposed in the vicinity of said concerned pixel.

5. An image processing apparatus as set forth in claim 1, in which

said gradient coefficient and said image quality adjusting value are determined based on the amount of noise contained in said image data.

2. An image processing apparatus, comprising:

image data inputting means for inputting image data;

edge strength calculating means comprising a processor operable to execute program modules for calculating an edge strength along a specific direction based on a difference of level between a concerned pixel of said inputted image data and a pixel disposed in vicinity of said concerned pixel;

filter processing means comprising a processor operable to execute program modules for determining a filter based on said edge strength along said specific direction calculated by said edge strength calculating means, carrying out filter processing on pixel data, and selectively performing noise reduction and edge enhancement by way of said filter;

edge enhancement signal generating means for generating an edge enhancement signal based on said pixel data on which said filter processing has been carried out; and

image correcting means for correcting said inputted image data based on said edge enhancement signal, wherein

said specific direction includes at least a horizontal direction and a vertical direction,

said edge strength calculating means includes a horizontal edge strength calculating unit for calculating an edge strength along a horizontal direction based on a difference of data level between said concerned pixel and pixels respectively disposed in left and right sides of said concerned pixel, and a vertical edge strength calculating unit for calculating an edge strength along a vertical direction based on a difference of data level between said concerned pixel and pixels respectively disposed in upper and lower sides of said concerned pixel,

said filter processing means includes a horizontal filter processing unit for calculating a horizontal filter based on said edge strength along said horizontal direction calculated by said horizontal edge strength calculating unit and selectively performing horizontal noise reduction and horizontal edge enhancement using said horizontal filter, and a vertical filter processing unit for calculating a vertical filter based on said edge strength along said vertical direction calculated by said vertical edge strength calculating unit and selectively performing vertical noise reduction and vertical edge enhancement using said vertical filter, and

said edge enhancement signal generating means is operable to generate an edge enhancement signal based on data of pixel on which said horizontal filter processing has been carried out and data of pixel on which said vertical filter processing has been carried out.

6. An image processing apparatus as set forth in claim 2, in which

said edge strength calculating means further includes a first diagonal direction edge strength calculating unit for calculating an edge strength along a first diagonal direction based on a difference of data level between said concerned pixel and pixels respectively disposed in upper and lower sides of said concerned pixel along said first diagonal direction, and a second diagonal direction edge strength calculating unit for calculating an edge strength along a second diagonal direction based on a difference of data level between said concerned pixel and pixels respectively disposed in upper and lower sides of said concerned pixel along said second diagonal direction,

said filter processing means includes a first diagonal direction filter processing unit for calculating a first diagonal direction filter based on said edge strength along said first diagonal direction calculated by said first diagonal direction edge strength calculating unit and selectively performing first diagonal direction noise reduction and first diagonal direction edge enhancement using said first diagonal direction filter, and a second diagonal direction filter processing unit for calculating a second diagonal direction filter based on said edge strength along said second diagonal direction calculated by said second diagonal direction edge strength calculating unit and selectively performing second diagonal direction noise reduction and second diagonal direction edge enhancement using said second diagonal filter, and

said edge enhancement signal generating means is operative to generate an edge enhancement signal based on data of pixel on which said first diagonal direction filter processing has been carried out and data of pixel on which said second diagonal direction filter processing has been carried out.

3. An image processing method, comprising:

image data inputting step for inputting image data;

edge strength calculating step for calculating a plurality of edge strengths along a plurality of directions based on a difference of level between a concerned pixel of said inputted image data and a pixel disposed in vicinity of said concerned pixel;

filter processing step for determining a plurality of filters based on said edge strengths along said plurality of directions calculated by said edge strength calculating means, carrying out filter processing on pixel data, and selectively performing noise reduction and edge enhancement by way of said filters,

edge enhancement signal generating step for generating an edge enhancement signal based on said pixel data on which said filter processing has been carried out; and

image correcting step for correcting said inputted image data based on said edge enhancement signal, wherein

said plurality of directions includes at least a horizontal direction and a vertical direction,

said edge strength calculating step includes a horizontal edge strength calculating step for calculating an edge strength along a horizontal direction based on a difference of data level between said concerned pixel and pixels respectively disposed in left and right sides of said concerned pixel, and a vertical edge strength calculating step for calculating an edge strength along a vertical direction based on a difference of data level between said concerned pixel and pixels respectively disposed in upper and lower sides of said concerned pixel,

said filter processing step includes a horizontal filter processing step for calculating a horizontal filter based on said edge strength along said horizontal direction calculated in said horizontal edge strength calculating step and selectively performing horizontal noise reduction and horizontal edge enhancement using said horizontal filter, and a vertical filter processing step for calculating a vertical filter based on said edge strength along said vertical direction calculated in said vertical edge strength calculating step and selectively performing vertical noise reduction and vertical edge enhancement using said vertical filter, and

said edge enhancement signal generating step is to generate an edge enhancement signal based on data of pixel on which said horizontal filter processing has been carried out and data of pixel on which said vertical filter processing has been carried out.