【opencv+python】图像的基本操作：缩放、剪切、位移、旋转、仿射变换

1.缩放

代码：

# 使用resize函数实现图片缩放
import cv2 src = cv2.imread("C:/360Downloads/1.jpg", 1) cv2.imshow("src", src) srcInfo = src.shape height = srcInfo[0] width = srcInfo[1] dstHeight = int(height * 0.5) dstWidth = int(width * 0.5) dst = cv2.resize(src, (dstWidth, dstHeight)) cv2.imshow("dst", dst) cv2.waitKey(0) 
 # 使用warpAffine函数实现图片缩放
import cv2 import numpy as np src = cv2.imread("C:/360Downloads/1.jpg", 1) cv2.imshow("src", src) srcInfo = src.shape height = int(srcInfo[0]/2) width = int(srcInfo[1]/2) # 将图片缩小为原来的一半： # xNew = x * 0.5 # yNew = y * 0.5

# xNew = x * A1 + y * A2 + B1 # yNew = x * A3 + y * A4 + B2

# np.float32([[A1, A3, B1], # [A2, A4, B2]])
matScale = np.float32([[0.5, 0, 0], [0, 0.5, 0]]) dst = cv2.warpAffine(src, matScale, (width, height)) cv2.imshow("dst", dst) cv2.waitKey(0)

效果：

 

 

2.剪切

代码：

# 图片剪切
import cv2 src = cv2.imread("C:/360Downloads/1.jpg", 1) cv2.imshow("src", src) 
# [行，列] dst = src[100:200, 100:300] cv2.imshow("dst", dst) cv2.waitKey(0)

效果：

 

 

3.位移

代码：

# 图像位移
import cv2 import numpy as np src = cv2.imread("C:/360Downloads/1.jpg", 1) cv2.imshow("src", src) srcInfo = src.shape height = srcInfo[0] width = srcInfo[1] # 左移100，下移200： # xNew = x + 100 # yNew = y + 200

# xNew = x * A1 + y * A2 + B1 # yNew = x * A3 + y * A4 + B2

# np.float32([[A1, A3, B1], # [A2, A4, B2]])
matShift = np.float32([[1, 0, 100], [0, 1, 200]]) dst = cv2.warpAffine(src, matShift, (width, height)) cv2.imshow("dst", dst) cv2.waitKey(0)

效果：

 

 

4.旋转

代码：

# 旋转图像
import cv2 src = cv2.imread("C:/360Downloads/1.jpg", 1) cv2.imshow("src", src) srcInfo = src.shape height = srcInfo[0] width = srcInfo[1] # getRotationMatrix2D 函数可获取旋转的仿射矩阵 # 参数依次为（旋转中心，旋转角度，缩放比例）
matRotate = cv2.getRotationMatrix2D((0, 0), 45, 0.5) dst = cv2.warpAffine(src, matRotate, (width, height)) cv2.imshow("dst", dst) cv2.waitKey(0)

效果：

 

 

5.仿射变换

代码：

# 仿射变换
import cv2 import numpy as np src = cv2.imread("C:/360Downloads/1.jpg", 1) cv2.imshow("src", src) srcInfo = src.shape height = srcInfo[0] width = srcInfo[1] # 三点确定一个平面 # getAffineTransform 函数可获取仿射矩阵 # 参数依次为（源图像的三点坐标，目标图像的三点坐标） # 三点分别为（左上角，左下角，右上角）
matSrc = np.float32([[0, 0], [0, height - 1], [width - 1, 0]]) matDst = np.float32([[50, 50], [150, height - 100], [width - 100, 150]]) matAffine = cv2.getAffineTransform(matSrc, matDst) dst = cv2.warpAffine(src, matAffine, (width, height)) cv2.imshow("dst", dst) cv2.waitKey(0)

效果：