lecture09_Image_Restoration_bw_2in1

(Gamma) noise

Impulse (Salt-and-Pepper) noise

The Hong Kong University of Science and Technology

Department of Electronic and Computer Engineering

Noise Effect

Noise Effect

The Hong Kong University of Science and Technology

Department of Electronic and Computer Engineering

Estimation of Noise Parameters

Use image system to capture a flat environment

and check the histogram

Use mean and standard deviation to estimate a and b for non-Gaussian noise distribution

15 The Hong Kong University of Science and Technology

Department of Electronic and Computer Engineering

Lecture Outline

The Hong Kong University of Science and Technology Department of Electronic and Computer Engineering

X-Ray Image with salt-and-pepper noise Result with 3 x 3

arithmetic mean

filter

Result with 3 x 3

median filter

Tradeoff between noise-reduction and blurring

Example of Max and Min Filtering

Q: What would happen if max and min filters were swapped here? The Hong Kong University of Science and Technology

The Hong Kong University of Science and Technology

Department of Electronic and Computer Engineering

Example: Adaptive Median Filtering

Non-Adaptive Median Filter Adaptive Median Filter

The Hong Kong University of Science and Technology

Department of Electronic and Computer Engineering

Band -Reject Filters

Ideal

Band -Reject Example

Math forms:

The Hong Kong University of Science and Technology

Department of Electronic and Computer Engineering

Notch Filtering Example

Note: Optimized notch-filtering procedures also possible (see Section 5.4.4 in text)