opencv: 旋转图片

import cv2
img = cv2.imread("./origin.jpg")

h, w = img.shape[:2]
center = (w // 2, h // 2)

M = cv2.getRotationMatrix2D(center, 45, 0.5)
rotated = cv2.warpAffine(img, M, (w, h))
cv2.imwrite("./rotated.jpg", rotated)

# encoding:utf-8

import cv2
img = cv2.imread("./girl.jpg")

h, w = img.shape[:2]
center = (w // 2, h // 2)

# 旋转中心坐标，逆时针旋转：45°，缩放因子：0.5
M_1 = cv2.getRotationMatrix2D(center, 45, 0.5)
rotated_1 = cv2.warpAffine(img, M_1, (w, h))
cv2.imwrite("./rotated_45.jpg", rotated_1)

# 旋转中心坐标，逆时针旋转：-90°，缩放因子：1
M_2 = cv2.getRotationMatrix2D(center, -90, 1)
rotated_2 = cv2.warpAffine(img, M_2, (w, h))
cv2.imwrite("./rotated_-90.jpg", rotated_2)