noise models

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5/13/2013 COMSATS Institute of Information Technology, Abbottabad Digital Image Processing CSC330 1 Digital Image Processing Image Restoration Noise models and additive noise removal

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noise models in images

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Page 1: Noise Models

5/13/2013 COMSATS Institute of Information Technology, Abbottabad Digital Image Processing CSC330 1

Digital Image Processing

Image Restoration

Noise models and additive noise removal

Page 2: Noise Models

5/13/2013 COMSATS Institute of Information Technology, Abbottabad Digital Image Processing CSC330 2

Image Restoration

Page 3: Noise Models

5/13/2013 COMSATS Institute of Information Technology, Abbottabad Digital Image Processing CSC330 3

Image Restoration

What is noise (in the context of image processing) and how can it be modeled?

What are the main types of noise that may affect an image? What are the possible solutions?

Subjective Vs Objective (Enhancement Vs Restoration)

Page 4: Noise Models

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Degradation Model for a Digital Image

Page 5: Noise Models

5/13/2013 COMSATS Institute of Information Technology, Abbottabad Digital Image Processing CSC330 5

Noise Models

Page 6: Noise Models

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Noise and Noise Models

Gaussian (normal) Impulse (salt-and-pepper) Uniform Rayleigh Gamma (Erlang) Exponential

Page 7: Noise Models

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Effect of Noise on Images & Histograms

Gaussian

Exponential

Impulse (salt-and-pepper)

Page 8: Noise Models

5/13/2013 COMSATS Institute of Information Technology, Abbottabad Digital Image Processing CSC330 8

Effect of Noise on Images & Histograms

Rayleigh

Gamma (Erlang)

Uniform

Page 9: Noise Models

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Noise Models: Gaussian Noise

Page 10: Noise Models

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Noise Models: Rayleigh Noise

Page 11: Noise Models

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Noise Models: Erlang (Gamma) Noise

Page 12: Noise Models

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Noise Models: Exponential Noise

Where

Page 13: Noise Models

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Noise Models: Uniform Noise

The mean and variance are given by

otherwise 0

if ,1)(

bzaabzp

12)(,

2

22 abba

Page 14: Noise Models

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Noise Models: Impulse (Salt and Pepper) Noise

Page 15: Noise Models

5/13/2013 COMSATS Institute of Information Technology, Abbottabad Digital Image Processing CSC330 15

Effect of Noise on Images & Histograms

Page 16: Noise Models

5/13/2013 COMSATS Institute of Information Technology, Abbottabad Digital Image Processing CSC330 16

Effect of Noise on Images & Histograms

Page 17: Noise Models

5/13/2013 COMSATS Institute of Information Technology, Abbottabad Digital Image Processing CSC330 17

Effect of Noise on Images & Histograms

Page 18: Noise Models

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Periodic Noise (Example)

Spatially Dependent Case

Page 19: Noise Models

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Applicability of various noise models