OpenCV图像旋转

图像可以各种角度旋转(90、180、270和360)。 OpenCV计算执行仿射变换的仿射矩阵, 这意味着尽管保留了直线上的点之间的距离之比, 但它不会保留线之间的角度或点之间的距离。

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：它代表图像的中心。
• 角度：它表示特定图像沿逆时针方向旋转的角度。
• 旋转：保存旋转图像数据的ndarray。
• 比例尺：值1.0表示保留了形状。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