Image enhancement methods and apparatus therefor
First Claim
1. An image processing method comprising a transformation step of processing an input image signal to generate an adjusted output image signal, wherein the intensity values I(x,y) for different positions (x,y) of an image are adjusted to generate an adjusted intensity value Iout(x,y) in accordance with:
-
Iout=Σ
i=0Nα
i(I)LPFΩ
i[Pi(F(I))]·
Qi(F(I))+β
(I),where the Pi(γ
) form an orthogonal basis of functions of γ
defined in a range 0<
γ
<
1, the Qi(..) are antiderivatives of the Pi(..);
the Qi(F(I))=∫
0F(i)=Pi(η
)dη
or approximations thereto, the LPFΩ
[..] is an operator of low-pass spatial filtering;
the Ω
i are cut-off frequencies of the low-pass spatial filter, the F(..) is a weighting function, the α
i(l) are ith members of a transformation step strength function, the β
(I) is a strength function, the i and N are positive constants and the η
is a variable.
2 Assignments
0 Petitions
Accused Products
Abstract
The invention relates to methods, devices and computer programs for processing images. The dynamic range of an image is adjusted to allow more detail in the original image to be reproducible, whilst preserving the natural look of the image. Improvements to lossy data compression/decompression algorithms are proposed which include elements of spatial non-uniformity, for example modifying relatively dark portions of an image to a greater extent than relatively bright portions of the image. The algorithms may be made reversible by storing parameters describing the compression process with a compressed image, which can then be used to reverse the process when decompressing the image.
30 Citations
23 Claims
-
1. An image processing method comprising a transformation step of processing an input image signal to generate an adjusted output image signal, wherein the intensity values I(x,y) for different positions (x,y) of an image are adjusted to generate an adjusted intensity value Iout(x,y) in accordance with:
-
Iout=Σ
i=0Nα
i(I)LPFΩi [Pi(F(I))]·
Qi(F(I))+β
(I),where the Pi(γ
) form an orthogonal basis of functions of γ
defined in a range 0<
γ
<
1, the Qi(..) are antiderivatives of the Pi(..);
the Qi(F(I))=∫
0F(i)=Pi(η
)dη
or approximations thereto, the LPFΩ
[..] is an operator of low-pass spatial filtering;
the Ω
i are cut-off frequencies of the low-pass spatial filter, the F(..) is a weighting function, the α
i(l) are ith members of a transformation step strength function, the β
(I) is a strength function, the i and N are positive constants and the η
is a variable. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 23)
-
-
19. An image processing method comprising the step of processing an input image signal to generate an adjusted output image signal, wherein the intensity values (I) for different positions of an image are adjusted to generate an adjusted intensity value (I′
- ) in accordance with;
- View Dependent Claims (20, 21, 22)
- ) in accordance with;
Specification