1. Adaptive Enhancement Gang Wang Adaptive Adaptive unsharp masking An adaptive image enhancement algorithm

2. Adaptive Unsharp Masking Objective: emphasize the medium-contrast details than large- contrast details Linear unsharp masking

3. Adaptive Method Define a “desired output”, and adjust the weight factor to cause the output to agree as closely as possible with the desired output. Adaptation algorithm to recursively update

4. Quantify the regions Define smooth, medium-contrast, high-contrast regions

5. Local dynamics g() highpass filter to define local dynamics 8

6. Define “desired output”

7. Adaptation algorithm LMS/Newton algorithm(Gauss-Newton) Compute enhanced image

8. Demo original imagelinear UM adaptive UM

9. An adaptive image enhancement algorithm Objective: smooth the uniform areas and sharpen the borders Method (1) determine each pixel in homogenous region or not (Haralick method). (2) according to the position property, assign to each pixel a new digital number.

10. Haralick method

11. Haralick method (cont) F has an F distribution with 2,6 degrees of freedom (considering 3* 3 window,n=9) We are interested in a1=0,a2=0 (homogenous region) 1% significance test if F<10.9, homogenous region,otherwise not 5% significance test if F<5.14, homogenous region,otherwise not

12. Example

13. Results of F-test Use F-test to determine whether the window in a particular position is homogenous or not, if yes, mark 1;if not, mark 2 2 2 1 2 1 1 1 1 1 1 1 1 2 2 2 1 1 1 1 1 1 1 1 1 2 2 2 1 1 1 1 1 1 1 2 1 2 2 1 1 1 1 1 1 1 1 1 1 2 2 1 1 2 1 1 1 1 1 2 1 2 1 1 1 1 1 1 1 1 2 2 1 2 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 2 2 1 1 1 1 2 2 1 1 1 1 2 2 2 1 1 1 2 2 1 1 2 1 2 1 1 1 1 1 2 2 1 1 1 1 2 2 1 1 1 1 Results of F-test

14. Step 2: image enhancement procedure Based on the F-test matrix, the image enhancement procedure is accomplished by assigning new digital number to each pixel, through this, to sharpen the border and smooth the uniform area. Compute RV(reference value): If F_test(x,y)=1 RV is the average within the window. If F_test(x,y)=2 RV is taken as the highest or the lowest digital number within the window, the one closest to the digital number of the central pixel. Compute new digital number: DN(new)=WF*RV+(1-WF)*DN(old).

15. Demo original image enhanced image (5%) (one iteration) enhanced image (1%) (four iteration) enhanced image (1%) (one iteration) enhanced image (1%) 3 level (one iteration)