Spatial Filtering

1
Spatial Filtering

• ????? ??????
• ???
• ?? PG Steamer Users Guide

2
Filters

• General ?? ??? ??
• Average Filter, Mean Filter, Median Filter, Mode
  Filter, Edge Sharpening Filter
• Adaptive ?? ??? ?? ?? ??
• Lee Filter, Frost Filter, Gamma Filter
• Texture ??? ??
• Occurrence Measure, Co-occurrence Measure

3
Average Filter

• ??? ???? ?? ???? ???.
• ?) 3x3 average window kernel
• Result (a1a2a3a4a5a6a7a8a9)/9

4
Laplacian Edge Detect Filter

• ?? ??? ????? ????. (??? ?? ??)
• ?) 3x3 window kernel
• Result 1a21a4-4a51a61a8

5
Sobel Edge Detect Filter

• ?? ??? ????? ????. (??? ??? ??)
• 3x3 window 2?? kernel? ??
• x -1a11a3-2a42a6-1a71a9
• y 1a12a21a3-1a7-2a8-1a9
• Result

6
Roberts Edge Detect Filter

• ?? ??? ????? ????. (??? ??)
• 3x3 window 2?? kernel? ??
• x -1a31a5
• y -1a11a5
• Result

7
Prewitt Edge Detect Filter

• ?? ??? ????? ????. (??? ??? ??, ?? ??? ??)
• 3x3 window 2?? kernel? ??
• x -1a1-1a3a4-1a61a7-1a9
• y -1a1-1a2-1a31a71a81a9
• Result

8
Edge Sharpening Filter

• ??? ???? ???? ??
• ??? Average Filter? ??? ?, ?? ??? ??.

9
Median Filter

• ??? ???? ???? ?????? ??. Filter window ?? ????
  ??.
• ?) 3x3 window
• ???? (3,4,5,5,6,7,8,9,12)? ???? 6

10
Mode Filter

• Filter Window?? ?? ???? ??
• ?) 3x3 window
• ???? (2,3,4,4,4,5,6,9,9)? ?????? 4

11
Adaptive Filters

• ???? ??? ?????? ??? ???? ??.
• Speckle? ?? SAR ???? ??
• Lee Additive Filter, Lee Multiplicative Filter,
  Lee Additive and Multiplicative Filter, Enhanced
  Lee Filter, Frost Filter, Enhanced Frost Filter,
  Gamma Filter, Kuan Filter, Gaussian Smoothing
  Filter, Salt and Pepper Removal Filter

12
Texture Filters

• Occurrence Average, Standard Deviation,
  Entropy, Min-Max
• Co-occurrence Average, Standard Deviation,
  Angular Second Moment, Contrast, Correlation

13
User Defined Filters

• Arbitrary Filter Kernel

14
Frequency Filtering

• Forward Fast Fourier Transformation (FFT)
• ??? Frequency Domain ?? ??
• Frequency Filter ??
• Inverse FFT