1. Free International University of Moldova Faculty of Informatics and Engineering DIGITAL SYGNALS PROCESSING Course of lectures Theme: SIGNALS CONTRAST ENHANCEMENT Veacheslav L. Perju, DSC, Acad. Chisinau 2008

2. Signals Preprocessing 1. Signals contrast enhancement 2. Signals edge detection

3. SIGNALS CONTRAST ENHANCEMENT Introduction 1. Amplitude re scaling 2. Power low point contrast modification 3. Gaussian contrast modification 4. Logarithmic contrast modification 5. Reverse contrast modification 6. Inverse contrast modification 7. Histogram modification Conclusion Home work Literature

4. Definition of the contrast F(j,k) – input signal j=1÷J, k=1÷K max{F(j,k)} max{F(j,k)} CRT = _______________ min{F(j,k) min{F(j,k)

5. 2D signals

7. Operation of signals contrast enhancement F(j,k)  f{F(j,k)}= G(j,k) CRT G > CRT F CRT G > CRT F

8. Amplitude re scaling

12. Power low point contrast modification G(j,k)=[F(j,k)] t G(j,k)=[F(j,k)] t 0<=F(j,k)<=1

13. Power low point contrast modification

18. Gaussian contrast modification

19. Logarithmic contrast modification

20. Reverse contrast modification G(j,k)=1-F(j,k)

22. Inverse contrast modification

24. Histogram modification Histogram – the function which describe the nr of signals elements of different intensity

25. Histogram modification

32. Conclusion 1. Amplitude re scaling 2. Power low point contrast modification 3. Gaussian contrast modification 4. Logarithmic contrast modification 5. Reverse contrast modification 6. Inverse contrast modification 7. Histogram modification

33. Home work 1. To compare different methods 2. To elaborate the algorithms for signals contrast enhancement by: - Amplitude re scaling - Gaussian contrast modification - Histogram modification

34. Literature S. V. Vaseghi. Advanced Digital Signal Processing and Noise Reduction. John Willy&Sons, Ltd, 2002. http://dsp-book.narod.ru/adsnr.htm S.M. Kuo, B.H. Lee. Real Time Digital Signal Processing. John Wiley&Sons, Ltd, 2001. William K. Pratt. Digital Image Processing. John Wiley&Sons, Ltd, 2001. Сергиенко А. Цифровая обработка сигналов. СПб.:ПИТЕР, 2006 Optical Engineering Journal www.spie.org www.elsevier.com www.ieee.com