Systems and methods for color defringing
AssigneeConexant Systems, Inc.
InventorsRagnar H. Jonsson, Derek T. Walton, Trausti Thormundsson
Life of this patent
Estimating the term…
Abstract
A system and method for defringing chromatic aberrations that occur in imaging devices such as scanners. The system comprises shift filters to shift lines in the various color planes together. In addition in each color plane, a spread filter is used to compensate for the unequal point spread functions of each color. Furthermore, the results can be enhanced by filtering in the luminance-chrominance space.
Claims23
A color defringing filter:
- a red filter;
- a blue filter;
- a green filter;
- an red-green-blue (RGB) to luminance/chrominance (LC) converter coupled to the red filter, the blue filter and the green filter;
- a first chroma filter and a second chroma filter coupled to the RGB to LC converter;
- wherein the first chroma filter filters a first chroma component of the image in a scan direction and the second chroma filter filters a second chroma component of the image;
- wherein filtering the red component comprises applying a red shift filter in accordance with
- y
- r
-
- (
- n
- ,
- m
- )
- =
- 1
- 3
-
- x
- r
-
- (
- n
- ,
- m
- +
- 1
- )
- +
- 2
- 3
-
- x
- r
-
- (
- n
- ,
- m
- )
- ,
- where xr is a red component of an input image and yr is a red component of a filtered image y, and filtering the blue component comprises applying a blue shift filter.
A method of color defringing an image having a red component, a blue component and a green component, said method comprising:
- filtering the red component;
- filtering the blue component;
- filtering the green component;
- converting the red component, blue component, and green component into a luma component, a first chroma component and a second chroma component;
- filtering the first chroma component in a scan direction:
- and
- filtering the second chroma component in the scan direction, wherein filtering the red component comprises applying a red shift filter in accordance with
- y
- r
-
- (
- n
- ,
- m
- )
- =
- 1
- 3
-
- x
- r
-
- (
- n
- ,
- m
- +
- 1
- )
- +
- 2
- 3
-
- x
- r
-
- (
- n
- ,
- m
- )
- ,
- where xr is a red component of an input image and yr is a red component of a filtered image y, and filtering the blue component comprises applying a blue shift filter.
A color defringing filter operable to defringe an image having a red component, a blue component, and a green component, said filter comprising:
- means for filtering the red component;
- means for filtering the blue component;
- means for filtering the green component;
- means for converting the red component, blue component, and green component into a luma component,
- a first chroma component and a second chroma component;
- means for filtering the first chroma component;
- and
- means far filtering the second chroma component;
- wherein filtering the red component comprises applying a red shift filter in accordance with
- y
- r
-
- (
- n
- ,
- m
- )
- =
- 1
- 3
-
- x
- r
-
- (
- n
- ,
- m
- +
- 1
- )
- +
- 2
- 3
-
- x
- r
-
- (
- n
- ,
- m
- )
- ,
- where xr is a red component of an input image and yr is a red component of a filtered image y, and filtering the blue component comprises applying a blue shift filter.
A scanner comprising:
- a scan head;
- electronic logic comprising an external interface, processor, and memory;
- wherein the memory comprises instructions which causes the processor to defringe a scanned image having a red component, a blue component and a green component by filtering the red component by shifting a red pixel component in a scan direction by ⅓ pixel;
- filtering the blue component by shifting a blue pixel component in the scan direction by ⅓ pixel;
- converting the red component, blue component, and green component into a luma component, a first chroma component and a second chroma component;
- filtering the first chroma component in the scan direction;
- and
- filtering the second chroma component in the scan direction, wherein filtering the red component comprises applying a red shift filter in accordance with
- y
- r
-
- (
- n
- ,
- m
- )
- =
- 1
- 3
-
- x
- r
-
- (
- n
- ,
- m
- +
- 1
- )
- +
- 2
- 3
-
- x
- r
-
- (
- n
- ,
- m
- )
- ,
- where xr is a red component of an input image and yr is a red component of a filtered image y, and filtering the blue component comprises applying a blue shift filter.
Dependencies are inferred from the claim text.