1. Image
Enhancement
using Alpha
Rooting based
Hybrid Technique

2. Image Enhancement

3. Image Enhancement in Spatial domain

4. Gray Level Transformation Functions

5. Gray Level Transformation Functions

6. Negative Image Transformation
s = 1 - r
s = 1 – r
where, s = output image gray level
r = input image gray level

7. Log transformation
s = c log ( 1 + r ) where, c = scaling factor

8. Power law transformation function

9. Power law transformation function

10. Power law transformation function

11. Power law transformation function

12. By Alpha Rooting
Image Enhancement in Frequency
domain
Orthogonal transformation

13. 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

14. 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)

15. 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 darkening
of image which is artifact of alpha rooting
Requirements
• Eliminate Tonal change
• Achieve good contrast and brightness
Remedy
• Apply log transform
• Apply power law transform

16. 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

17. Experimental Results
(a)
(b) (c) (d)
Fig (a) : Original Image
Fig (b) : Alpha Rooted using α = 0.72
Fig (c) : Hybrid Alpha Rooted using
α = 0.78, b = 1.2, γ = 0.8
Fig (d) : Hybrid Alpha Rooted using
α = 0.7, b = 1.2, γ = 0.8

18. Experimental Results
Fig (a) : Original Image
Fig (b) : Alpha Rooted using α = 0.78
Fig (c) : Hybrid Alpha Rooted using
α = 0.75, b = 1.1, γ = 2
(a)
(b) (c)

19. CONCLUSION
In this paper we elucidated an Alpha Rooting Based Hybrid
Procedure for image enhancement which is free of the conventional
limitations associated with the transform domain image
enhancement techniques.

20. Thank You !!!