Add files via upload

eastmountyxz · web-flow · commit d85391a0c858 · 2019-10-18T00:10:10.000+08:00
diff --git a/blog22-fft/blog22-image02.py b/blog22-fft/blog22-image02.py
@@ -0,0 +1,26 @@
+# -*- coding: utf-8 -*-
+import cv2 as cv
+import numpy as np
+from matplotlib import pyplot as plt
+
+#读取图像
+img = cv.imread('lena.png', 0)
+
+#傅里叶变换
+f = np.fft.fft2(img)
+fshift = np.fft.fftshift(f)
+res = np.log(np.abs(fshift))
+
+#傅里叶逆变换
+ishift = np.fft.ifftshift(fshift)
+iimg = np.fft.ifft2(ishift)
+iimg = np.abs(iimg)
+
+#展示结果
+plt.subplot(131), plt.imshow(img, 'gray'), plt.title('Original Image')
+plt.axis('off')
+plt.subplot(132), plt.imshow(res, 'gray'), plt.title('Fourier Image')
+plt.axis('off')
+plt.subplot(133), plt.imshow(iimg, 'gray'), plt.title('Inverse Fourier Image')
+plt.axis('off')
+plt.show()
diff --git a/blog22-fft/blog22-image03.py b/blog22-fft/blog22-image03.py
@@ -0,0 +1,23 @@
+# -*- coding: utf-8 -*-
+import numpy as np
+import cv2
+from matplotlib import pyplot as plt
+
+#读取图像
+img = cv2.imread('lena.png', 0)
+
+#傅里叶变换
+dft = cv2.dft(np.float32(img), flags = cv2.DFT_COMPLEX_OUTPUT)
+
+#将频谱低频从左上角移动至中心位置
+dft_shift = np.fft.fftshift(dft)
+
+#频谱图像双通道复数转换为0-255区间
+result = 20*np.log(cv2.magnitude(dft_shift[:,:,0], dft_shift[:,:,1]))
+
+#显示图像
+plt.subplot(121), plt.imshow(img, cmap = 'gray')
+plt.title('Input Image'), plt.xticks([]), plt.yticks([])
+plt.subplot(122), plt.imshow(result, cmap = 'gray')
+plt.title('Magnitude Spectrum'), plt.xticks([]), plt.yticks([])
+plt.show()
diff --git a/blog22-fft/blog22-image04.py b/blog22-fft/blog22-image04.py
@@ -0,0 +1,26 @@
+# -*- coding: utf-8 -*-
+import numpy as np
+import cv2
+from matplotlib import pyplot as plt
+
+#读取图像
+img = cv2.imread('lena.png', 0)
+
+#傅里叶变换
+dft = cv2.dft(np.float32(img), flags = cv2.DFT_COMPLEX_OUTPUT)
+dftshift = np.fft.fftshift(dft)
+res1= 20*np.log(cv2.magnitude(dftshift[:,:,0], dftshift[:,:,1]))
+
+#傅里叶逆变换
+ishift = np.fft.ifftshift(dftshift)
+iimg = cv2.idft(ishift)
+res2 = cv2.magnitude(iimg[:,:,0], iimg[:,:,1])
+
+#显示图像
+plt.subplot(131), plt.imshow(img, 'gray'), plt.title('Original Image')
+plt.axis('off')
+plt.subplot(132), plt.imshow(res1, 'gray'), plt.title('Fourier Image')
+plt.axis('off')
+plt.subplot(133), plt.imshow(res2, 'gray'), plt.title('Inverse Fourier Image')
+plt.axis('off')
+plt.show()
diff --git a/blog22-fft/lena.png b/blog22-fft/lena.png
