Add 5

5/1.py

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+import cv2 as cv
+import numpy as np
+import matplotlib.pyplot as plt
+
+plt.rcParams["font.sans-serif"] = ["SimSun"]
+
+img = cv.imread(r"img\alphabet.jpg", cv.IMREAD_GRAYSCALE)
+
+dx = dy = 50
+rows, cols = img.shape[:2]
+M1 = np.float32([[1, 0, dx], [0, 1, dy]])  # type: ignore
+dst1 = cv.warpAffine(img, M1, (cols, rows))  # type: ignore
+
+M2 = cv.getRotationMatrix2D((cols / 2, rows / 2), 30, 1)
+dst2 = cv.warpAffine(img, M2, (cols, rows))
+
+M3 = np.float32([[1, 0, 0], [0, -1, rows]])  # type: ignore
+dst3 = cv.warpAffine(img, M3, (cols, rows))  # type: ignore
+
+plt.figure()
+plt.subplot(141)
+plt.imshow(img, cmap="gray")
+plt.title("待处理灰度图像")
+plt.axis("off")
+plt.subplot(142)
+plt.imshow(dst1, cmap="gray")
+plt.title("平移变换")
+plt.axis("off")
+plt.subplot(143)
+plt.imshow(dst2, cmap="gray")
+plt.title("旋转 30 度")
+plt.axis("off")
+plt.subplot(144)
+plt.imshow(dst3, cmap="gray")
+plt.title("垂直镜像")
+plt.axis("off")
+plt.tight_layout()
+plt.show()

5/2.py

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+import cv2 as cv
+import numpy as np
+import matplotlib.pyplot as plt
+
+plt.rcParams["font.sans-serif"] = ["SimSun"]
+
+img0 = cv.imread(r"img\alphabet.jpg", cv.IMREAD_GRAYSCALE)
+img1 = cv.copyMakeBorder(img0, 50, 50, 50, 50, cv.BORDER_CONSTANT, value=0)  # type: ignore
+pts1 = np.float32([[50, 50], [200, 50], [50, 200]])  # type: ignore
+pts2 = np.float32([[10, 70], [160, 50], [40, 220]])  # type: ignore
+rows, cols = img1.shape[:2]
+M1 = cv.getAffineTransform(pts1, pts2)  # type: ignore
+dst1 = cv.warpAffine(img1, M1, (cols, rows))
+M2 = cv.getAffineTransform(pts2, pts1)  # type: ignore
+dst2 = cv.warpAffine(dst1, M2, (cols, rows))
+
+plt.figure()
+plt.subplot(131)
+plt.imshow(img1, cmap="gray")
+plt.title("扩展后的图像")
+plt.axis("off")
+plt.subplot(132)
+plt.imshow(dst1, cmap="gray")
+plt.title("仿射变换图像")
+plt.axis("off")
+plt.subplot(133)
+plt.imshow(dst2, cmap="gray")
+plt.title("放射校正图像")
+plt.axis("off")
+plt.tight_layout()
+plt.show()

5/3.py

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+import cv2 as cv
+import matplotlib.pyplot as plt
+
+plt.rcParams["font.sans-serif"] = ["SimSun"]
+
+img0 = cv.imread(r"img\alphabet.jpg")
+imgT = cv.cvtColor(img0, cv.COLOR_BGR2GRAY)
+cv.rectangle(img0, (160, 140), (190, 170), (255, 0, 0), 3)
+img = imgT[140:170, 160:190]
+img1 = cv.resize(img, None, fx=10, fy=10, interpolation=cv.INTER_NEAREST)
+img2 = cv.resize(img, None, fx=10, fy=10, interpolation=cv.INTER_LINEAR)
+img3 = cv.resize(img, None, fx=10, fy=10, interpolation=cv.INTER_CUBIC)
+
+plt.figure()
+plt.subplot(141)
+plt.imshow(img0, cmap="gray")
+plt.title("原图像")
+plt.axis("off")
+plt.subplot(142)
+plt.imshow(img1, cmap="gray")
+plt.title("最近邻插值")
+plt.axis("off")
+plt.subplot(143)
+plt.imshow(img2, cmap="gray")
+plt.title("双线性插值")
+plt.axis("off")
+plt.subplot(144)
+plt.imshow(img3, cmap="gray")
+plt.title("双三次插值")
+plt.axis("off")
+plt.tight_layout()
+plt.show()

5/4.py

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+import cv2 as cv
+import numpy as np
+import matplotlib.pyplot as plt
+
+plt.rcParams["font.sans-serif"] = ["SimSun"]
+
+img0 = cv.imread(r"img\alphabet.jpg", cv.IMREAD_GRAYSCALE)
+img1 = cv.copyMakeBorder(img0, 20, 20, 20, 20, cv.BORDER_CONSTANT, value=0)  # type: ignore
+pts1 = np.float32([[20, 20], [220, 20], [20, 220]])  # type: ignore
+pts2 = np.float32([[10, 70], [160, 50], [40, 220]])  # type: ignore
+rows, cols = img1.shape[:2]
+M1 = cv.getAffineTransform(pts1, pts2)  # type: ignore
+dst1 = cv.warpAffine(img1, M1, (cols, rows))
+M2 = cv.getAffineTransform(pts2, pts1)  # type: ignore
+dst2 = cv.warpAffine(dst1, M2, (cols, rows))
+
+plt.figure()
+plt.subplot(131)
+plt.imshow(img1, cmap="gray")
+plt.title("扩展后的图像")
+plt.axis("off")
+plt.subplot(132)
+plt.imshow(dst1, cmap="gray")
+plt.title("仿射变换图像")
+plt.axis("off")
+plt.subplot(133)
+plt.imshow(dst2, cmap="gray")
+plt.title("放射校正图像")
+plt.axis("off")
+plt.tight_layout()
+plt.show()