image filtering. problem! noise is a problem, even in images! gaussian noisesalt and pepper noise
Post on 22-Dec-2015
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![Page 1: Image Filtering. Problem! Noise is a problem, even in images! Gaussian NoiseSalt and Pepper Noise](https://reader030.vdocuments.mx/reader030/viewer/2022032704/56649d7f5503460f94a62ca9/html5/thumbnails/1.jpg)
Image Filtering
![Page 2: Image Filtering. Problem! Noise is a problem, even in images! Gaussian NoiseSalt and Pepper Noise](https://reader030.vdocuments.mx/reader030/viewer/2022032704/56649d7f5503460f94a62ca9/html5/thumbnails/2.jpg)
Problem!
• Noise is a problem, even in images!
Gaussian Noise Salt and Pepper Noise
![Page 3: Image Filtering. Problem! Noise is a problem, even in images! Gaussian NoiseSalt and Pepper Noise](https://reader030.vdocuments.mx/reader030/viewer/2022032704/56649d7f5503460f94a62ca9/html5/thumbnails/3.jpg)
What to do?
• Try to think of ways to remove the noise!
Gaussian Noise Salt and Pepper Noise
![Page 4: Image Filtering. Problem! Noise is a problem, even in images! Gaussian NoiseSalt and Pepper Noise](https://reader030.vdocuments.mx/reader030/viewer/2022032704/56649d7f5503460f94a62ca9/html5/thumbnails/4.jpg)
Smoothing
• The most obvious and easy way to remove the noise is by averaging.
• We can average pixels of a specific neighborhood by convolution with an averaging filter.
![Page 5: Image Filtering. Problem! Noise is a problem, even in images! Gaussian NoiseSalt and Pepper Noise](https://reader030.vdocuments.mx/reader030/viewer/2022032704/56649d7f5503460f94a62ca9/html5/thumbnails/5.jpg)
Smoothing
• Convolution is a simple mathematical operation.
![Page 6: Image Filtering. Problem! Noise is a problem, even in images! Gaussian NoiseSalt and Pepper Noise](https://reader030.vdocuments.mx/reader030/viewer/2022032704/56649d7f5503460f94a62ca9/html5/thumbnails/6.jpg)
Smoothing
• Smoothing using 3x3 mean filter.
Gaussian Noise Salt and Pepper Noise
![Page 7: Image Filtering. Problem! Noise is a problem, even in images! Gaussian NoiseSalt and Pepper Noise](https://reader030.vdocuments.mx/reader030/viewer/2022032704/56649d7f5503460f94a62ca9/html5/thumbnails/7.jpg)
Gaussian Filter
• Gaussian filter is more natural!
![Page 8: Image Filtering. Problem! Noise is a problem, even in images! Gaussian NoiseSalt and Pepper Noise](https://reader030.vdocuments.mx/reader030/viewer/2022032704/56649d7f5503460f94a62ca9/html5/thumbnails/8.jpg)
Gaussian Filter
• Gaussian mask with σ=1.
![Page 9: Image Filtering. Problem! Noise is a problem, even in images! Gaussian NoiseSalt and Pepper Noise](https://reader030.vdocuments.mx/reader030/viewer/2022032704/56649d7f5503460f94a62ca9/html5/thumbnails/9.jpg)
Gaussian Filter
• Gaussian filter is more natural!
Gaussian Noise Gaussian 5x5 Filter
![Page 10: Image Filtering. Problem! Noise is a problem, even in images! Gaussian NoiseSalt and Pepper Noise](https://reader030.vdocuments.mx/reader030/viewer/2022032704/56649d7f5503460f94a62ca9/html5/thumbnails/10.jpg)
Median Filter
• Median filter operation.
![Page 11: Image Filtering. Problem! Noise is a problem, even in images! Gaussian NoiseSalt and Pepper Noise](https://reader030.vdocuments.mx/reader030/viewer/2022032704/56649d7f5503460f94a62ca9/html5/thumbnails/11.jpg)
Median Filter
• Removing Salt and Pepper Noise using Median Filtering.
Salt and Pepper Noise 3x3 Median Filter
![Page 12: Image Filtering. Problem! Noise is a problem, even in images! Gaussian NoiseSalt and Pepper Noise](https://reader030.vdocuments.mx/reader030/viewer/2022032704/56649d7f5503460f94a62ca9/html5/thumbnails/12.jpg)
Edge Detection
• Finding the edges of images is a very useful tool.
• How do we find the edges in images?
![Page 13: Image Filtering. Problem! Noise is a problem, even in images! Gaussian NoiseSalt and Pepper Noise](https://reader030.vdocuments.mx/reader030/viewer/2022032704/56649d7f5503460f94a62ca9/html5/thumbnails/13.jpg)
Edge Detection
• Yes you’re right, derivatives!!
![Page 14: Image Filtering. Problem! Noise is a problem, even in images! Gaussian NoiseSalt and Pepper Noise](https://reader030.vdocuments.mx/reader030/viewer/2022032704/56649d7f5503460f94a62ca9/html5/thumbnails/14.jpg)
Edge Detection
• We use image filtering to find edges.• There are many masks: Prewitt, Sobel, Roberts
Roberts
Sobel
Prewitt
![Page 15: Image Filtering. Problem! Noise is a problem, even in images! Gaussian NoiseSalt and Pepper Noise](https://reader030.vdocuments.mx/reader030/viewer/2022032704/56649d7f5503460f94a62ca9/html5/thumbnails/15.jpg)
Edge Detection
• The gradient magnitude and gradient angle can be calculated as follows: