image enhancement using alpha rooting based hybrid technique
TRANSCRIPT
Image Enhancement using Alpha
Rooting based Hybrid Technique
Image Enhancement
Image Enhancement in Spatial domain
Gray Level Transformation Functions
Gray Level Transformation Functions
Negative Image Transformation
s = 1 - r
s = 1 – r
where, s = output image gray level
r = input image gray level
Log transformation
s = c log ( 1 + r ) where, c = scaling factor
Power law transformation function
Power law transformation function
Power law transformation function
Power law transformation function
By Alpha Rooting
Image Enhancement in Frequency domain
Orthogonal transformation
Image
|X(p,s)|
Magnitude(contains frequency
content of image)
θ(p,s)
Phase(angle of the
magnitude content)
Orthogonal transform
X(p,s) = |X(p,s)| e jθ(p,s)
Orthogonal transformation
Inverse Orthogonal transform
Enhanced Image
Operation
Separation
Combination
Alpha Rooting
X(p,s) = |X(p,s)| e jθ(p,s)α^
• Operation in orthogonal transformation,
where, 0 < α < 1
• here, X(p,s) is alpha rooted image^
(a) (b)
Alpha Rooting Based Enhancement Procedure
Conventional Alpha Rooting results in• Subtle edge information in images• Increases sharpness• Makes image crisper
Enhancement in sharpness is mostly subdued by overall darkeningof image which is artifact of alpha rooting
Requirements• Eliminate Tonal change• Achieve good contrast and brightness
Remedy• Apply log transform• Apply power law transform
Proposed Method
Input Image
Apply Orthogonal Transformation
Separate Magnitude and phase coefficients
X(p,s) = |X(p,s)| e jθ(p,s)
Apply Alpha Rooting on magnitude|X(p,s)|α
Combine Magnitude and
phase components
Inverse Orthogonal Transform
Apply Log Transformation
s = c log(1+r)
Apply Power Law Transformation
s = b rγ
Enhanced Image
Experimental Results
(a)
(b) (c) (d)
Fig (a) : Original ImageFig (b) : Alpha Rooted using α = 0.72Fig (c) : Hybrid Alpha Rooted using α = 0.78, b = 1.2, γ = 0.8Fig (d) : Hybrid Alpha Rooted using α = 0.7, b = 1.2, γ = 0.8
Experimental Results
Fig (a) : Original ImageFig (b) : Alpha Rooted using α = 0.78Fig (c) : Hybrid Alpha Rooted using α = 0.75, b = 1.1, γ = 2
(a)
(b) (c)
CONCLUSION
In this paper we elucidated an Alpha Rooting Based HybridProcedure for image enhancement which is free of the conventionallimitations associated with the transform domain imageenhancement techniques.
Thank You !!!