Back to results
US 8,542,944 B2Granted
Method and apparatus for multi-scale based dynamic range compression and noise suppression
AssigneeShenzhen Mindray Bio-Medical Electronics Co., Ltd.
InventorWenwu Sun
Life of this patent
Estimating the term…
Abstract
An input image is decomposed into a residual image and a set of detail images in different levels of a hierarchy. The set of detail images are enhanced after which noise reduction filtering is directly applied to the enhanced set of detail images without the need to apply noise estimation to a local area of the enhanced set of detail image in advance. The residual image and the set of detail images with reduced noise are recomposed so as to obtain resultant image.
Claims17
An apparatus for processing an input image, comprising:
- an image decomposition unit for decomposing the input image into a residual image and a set of detail images in different levels of a hierarchy, wherein at least one detail image differs from the input image and comprises detail information from a high frequency band;
- an image enhancement unit for enhancing the set of detail images;
- a noise suppression unit for reducing noise of the enhanced set of detail images without applying noise estimation to a local area of the enhanced set of detail images in advance,
- wherein the noise suppression unit directly applies noise reduction processing to each of the enhanced detail images;
- an image reconstruction unit for recomposing the residual image and the set of detail images with reduced noise so as to obtain a resultant image;
- and
- a dynamic range compression unit for applying dynamic range compression to the enhanced set of detail images and the residual image;
- wherein the dynamic range compression unit compresses the residual image by weighted averaging the residual image and a uniform image.
5 more elements
A method for processing an input image, comprising:
- decomposing the input image into a residual image and a set of detail images in different levels of a hierarchy, wherein at least one detail image differs from the input image and comprises detail information from a high frequency band;
- enhancing the set of detail images;
- reducing noise of the enhanced set of detail images without applying noise estimation to a local area of the enhanced set of detail images in advance,
- wherein reducing noise comprises directly applying noise reduction processing to each of the enhanced detail images;
- recomposing the residual image and the set of detail images with reduced noise so as to obtain a resultant image;
- and
- applying dynamic range compression to the enhanced set of detail images and the residual image;
- wherein the dynamic range compression step compresses the residual image by weighted averaging the residual image and a uniform image.
5 more elements
An apparatus for processing an input image, comprising:
- means for decomposing the input image into a residual image and a set of detail images in different levels of a hierarchy, wherein at least one detail image differs from the input image and comprises detail information from a high frequency band;
- means for enhancing the set of detail images;
- means for reducing noise of the enhanced set of detail images without applying noise estimation to a local area of the enhanced set of detail images in advance,
- wherein the means for reducing noise directly applies noise reduction processing to each of the enhanced detail images;
- means for recomposing the residual image and the set of detail images with reduced noise so as to obtain a resultant image;
- and
- means for applying dynamic range compression to the enhanced set of detail images and the residual image;
- wherein the means for applying dynamic range compression compresses the residual image by weighted averaging the residual image and a uniform image.
5 more elements
A non-transitory computer-readable storage medium comprising program code for causing a computer to perform a method for processing an input image, the method comprising:
- decomposing the input image into a residual image and a set of detail images in different levels of a hierarchy, wherein at least one detail image differs from the input image and comprises detail information from a high frequency band;
- enhancing the set of detail images;
- reducing noise of the enhanced set of detail images without applying noise estimation to a local area of the enhanced set of detail images in advance,
- wherein reducing noise comprises directly applying noise reduction processing to each of the enhanced detail images;
- and
- recomposing the residual image and the set of detail images with reduced noise so as to obtain a resultant image;
- and
- applying dynamic range compression to the enhanced set of detail images and the residual image;
- wherein the dynamic range compression step compresses the residual image by weighted averaging the residual image and a uniform image.
6 more elements
An apparatus for processing an input image, comprising:
- an image decomposition unit for decomposing the input image into a residual image and a set of detail images in different levels of a hierarchy, wherein at least one detail image differs from the input image and comprises detail information from a high frequency band;
- an image enhancement unit for enhancing the set of detail images;
- a noise suppression unit for reducing noise of the enhanced set of detail images without applying noise estimation to a local area of the enhanced set of detail images in advance,
- wherein the noise suppression unit directly applies noise reduction processing to each of the enhanced detail images;
- and
- an image reconstruction unit for recomposing the residual image and the set of detail images with reduced noise so as to obtain a resultant image;
- wherein the noise suppression is a noise filter for retaining detail edge information for the enhanced set of detail images while reducing the noise of the enhanced set of detail images;
- wherein, with the noise filter, a pixel that is closer to a current pixel has greater influence on filtering of the current pixel, and a pixel that has a value differing farther from that of the current pixel has less influence on filtering of the current pixel;
- wherein the noise filter uses the following equation to reduce the noise of the enhanced set of detail images:
- L
- ″
-
- [
- p
- ,
- q
- ]
- =
- ∑
- j
- ≠
- 0
- ,
- k
- ≠
- 0
-
- L
- ′
-
- [
- p
- +
- j
- ,
- q
- +
- k
- ]
- ·
- exp
-
- (
- -
- r
- 2
- 3
- σ
- 2
- -
- (
- L
- ′
-
- [
- p
- +
- j
- ,
- q
- +
- k
- ]
- -
- L
- ′
-
- [
- p
- ,
- q
- ]
- )
- 2
- t
- 2
- )
- ∑
- j
- ≠
- 0
- ,
- k
- ≠
- 0
-
- exp
-
- (
- -
- r
- 2
- 3
- σ
- 2
- -
- (
- L
- ′
-
- [
- p
- +
- j
- ,
- q
- +
- k
- ]
- -
- L
- ′
-
- [
- p
- ,
- q
- ]
- )
- 2
- t
- 2
- )
- where, L′ and L″ are respectively images before and after filtering;
- r is the distance between pixel (p, q) and pixel (p+j, q+k) in the image L′, p and q are integers greater than or equal to 0, j and k are integers not equal to 0, and the values of j and k depending on the size of the noise filter;
- for the noise filter with a size of (2x+1)×(2y+1), |j|≦x and |k|≦y, and x and y are positive integers;
- σ is a constant for controlling the degree of spatial smoothness, the value of which is a real number greater than 0;
- and t is a constant representing a gray scale threshold which is a positive integer not greater than the maximum gray scale value in the image L′.
125 more elements
Dependencies are inferred from the claim text.