OpenCV图像旋转

17 Mar 2025 | 阅读 2 分钟

图像可以以各种角度（90、180、270 和 360 度）旋转。 OpenCV 计算执行仿射变换的仿射矩阵，这意味着它不会保留线条之间的角度或点之间的距离，尽管它保留了在线条上点的距离比率。

旋转图像的语法如下：

cv2.getRotationMatrix2D(center, angle, scale rotated = cv2.warpAfifne(img,M,(w,h))

参数

中心： 它表示图像的中心。
角度： 它表示要逆时针旋转特定图像的角度。
rotated： 保存旋转图像数据的 ndarray。
比例： 值 1.0 表示形状被保留。根据提供的值缩放图像。

示例-1

import cv2
# read image as greyscale
img = cv2.imread(r'C:\Users\DEVANSH SHARMA\cat.jpeg')
# get image height, width
(h, w) = img.shape[:2]
# calculate the center of the image
center = (w / 2, h / 2)

angle90 = 90
angle180 = 180
angle270 = 270

scale = 1.0

# Perform the counterclockwise rotation holding at the center
# 90 degrees
M = cv2.getRotationMatrix2D(center, angle90, scale)
rotated90 = cv2.warpAffine(img, M, (h, w))

# 180 degrees
M = cv2.getRotationMatrix2D(center, angle180, scale)
rotated180 = cv2.warpAffine(img, M, (w, h))

# 270 degrees
M = cv2.getRotationMatrix2D(center, angle270, scale)
rotated270 = cv2.warpAffine(img, M, (h, w))

cv2.imshow('Original Image', img)
cv2.waitKey(0)  # waits until a key is pressed
cv2.destroyAllWindows()  # destroys the window showing image

cv2.imshow('Image rotated by 90 degrees', rotated90)
cv2.waitKey(0)  # waits until a key is pressed
cv2.destroyAllWindows()  # destroys the window showing imag

cv2.imshow('Image rotated by 180 degrees', rotated180)
cv2.waitKey(0)  # waits until a key is pressed
cv2.destroyAllWindows()  # destroys the window showing image

cv2.imshow('Image rotated by 270 degrees', rotated270)
cv2.waitKey(0)  # waits until a key is pressed
cv2.destroyAllWindows()  # destroys the window showing image

输出