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# Chapter 4 Image Enhancement in the Frequency Domain

Chapter 4 Image Enhancement in the Frequency Domain. Chapter 4 Image Enhancement in the Frequency Domain. Chapter 4 Image Enhancement in the Frequency Domain. MATLAB/Image Processing Toolbox. MATLAB Fourier transforms &gt;&gt; f=imread(‘Figure_Rectangle.jpg’); % load in spatial rectangle

## Chapter 4 Image Enhancement in the Frequency Domain

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1. Chapter 4 Image Enhancement in the Frequency Domain

2. Chapter 4 Image Enhancement in the Frequency Domain

3. Chapter 4 Image Enhancement in the Frequency Domain

4. MATLAB/Image Processing Toolbox MATLAB Fourier transforms >> f=imread(‘Figure_Rectangle.jpg’); % load in spatial rectangle >> F=fft2(f); % do 2D FFT >> S=abs(F); % determine magnitude for display >> imshow(S, [ ]) % shows in four corners of display >> Fc=fftshift(F); % shift FFT to center >> imshow(abs(Fc), [ ]); % show magnitude of FFT in center % much tougher to do display transform >> g=im2unit8(mat2gray(log(1+double(f)))); >> imshow(g) % double converts the image to double precision floating point % mat2gray brings the values to the range [0,1] % im2unit8 brings the values back to the range [0,255] % general log transform >> g=im2unit8(mat2gray(c*log(1+double(f)))); SEE GWE, Section 4.2 Computing and Visualizing the 2-D DFT in MATLAB GWE, Section 3.2.2 Logarithmic and Contrast Stretching Transformations

5. Chapter 4 Image Enhancement in the Frequency Domain

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