1.3.1 Filters to Reduce Noise and
Distortion, or to Enhance
- Median Filter - replaces pixel with median value in
sliding window (use 3x3 or radius 1), replaces isolated noise pixels,
preserves edges, but cuts corners (loses some high frequency signal)
- Mean Filter (Blur) - takes average of pixel values in sliding window (reduces noise but blurs image, is a low pass filter)
- Weighted Average (Gausian Blur) - gives center pixel greater weigh, with decreasing weight related to distance from center pixel
- Crimmins Speckle Removal - nonlinear (makes pixel brighter if neighbors are brighter or makes pixels darker if neighbers are darker), loses high frequency information; (may need to be repeated multiple times); not very effective difference
is to much between noise and background
