Digital Image Processing: Image Enhancement Frequency domain methods - Duong Anh Duc

Digital Image Processing: Image Enhancement Frequency domain methods - Duong Anh Duc provides about Image Enhancement - frequency domain methods; 1-d Fourier transform of a sequence; 2-d Fourier transform of a digital image; Fourier Transform of “Rice” Image; Importance of Phase Information in Images;. | 5/14/2020 4:35:04 AM Duong Anh Duc - Digital Image Processing Digital Image Processing Image Enhancement Frequency domain methods 5/14/2020 4:35:04 AM Duong Anh Duc - Digital Image Processing Image Enhancement: Frequency domain methods The concept of filtering is easier to visualize in the frequency domain. Therefore, enhancement of image f(m,n) can be done in the frequency domain, based on its DFT F(u,v) . This is particularly useful, if the spatial extent of the point-spread sequence h(m,n) is large. In this case, the convolution g(m,n) = h(m,n)*f(m,n) may be computationally unattractive. Enhanced Image PSS Given Image 5/14/2020 4:35:04 AM Duong Anh Duc - Digital Image Processing Frequency domain methods We can therefore directly design a transfer function H(u,v) and implement the enhancement in the frequency domain as follows: G(u,v) = H(u,v)*F(u,v) Enhanced Image Transfer Function Given Image 5/14/2020 4:35:04 AM Duong Anh Duc - Digital Image Processing 1-d . | 5/14/2020 5:31:14 AM Duong Anh Duc - Digital Image Processing Digital Image Processing Image Enhancement Frequency domain methods 5/14/2020 5:31:14 AM Duong Anh Duc - Digital Image Processing Image Enhancement: Frequency domain methods The concept of filtering is easier to visualize in the frequency domain. Therefore, enhancement of image f(m,n) can be done in the frequency domain, based on its DFT F(u,v) . This is particularly useful, if the spatial extent of the point-spread sequence h(m,n) is large. In this case, the convolution g(m,n) = h(m,n)*f(m,n) may be computationally unattractive. Enhanced Image PSS Given Image 5/14/2020 5:31:14 AM Duong Anh Duc - Digital Image Processing Frequency domain methods We can therefore directly design a transfer function H(u,v) and implement the enhancement in the frequency domain as follows: G(u,v) = H(u,v)*F(u,v) Enhanced Image Transfer Function Given Image 5/14/2020 5:31:14 AM Duong Anh Duc - Digital Image Processing 1-d Fourier transform of a sequence Given a 1-d sequence s[k], k={ ,-1,0,1,2, ,} Fourier transform Fourier transform is periodic with 2 Inverse Fourier transform 5/14/2020 5:31:14 AM Duong Anh Duc - Digital Image Processing 1-d Fourier transform of a sequence How is the Fourier transform of a sequence s[k] related to the Fourier transform of the continuous signal Continuous-time Fourier transform 5/14/2020 5:31:14 AM Duong Anh Duc - Digital Image Processing 2-d Fourier transform of a digital image Given a 2-d matrix of image samples s[m,n], m,n Z2 Fourier transform Fourier transform is 2 -periodic both in x and y Inverse Fourier transform 5/14/2020 5:31:14 AM Duong Anh Duc - Digital Image Processing 2-d Fourier transform of a digital image How is the Fourier transform of a sequence s[m,n] related to the Fourier transform of the continuous signal Continuous-space 2D Fourier transform 5/14/2020 5:31:14 AM Duong Anh Duc - Digital Image Processing Fourier Transform Example .