python 抠图算法_python+opencv抠图并旋转（根据坐标抠图）

import cv2

import numpy as np

def subimage(image, center, theta, width, height):

theta *= np.pi / 180 # convert to rad

v_x = (np.cos(theta), np.sin(theta))

v_y = (-np.sin(theta), np.cos(theta))

s_x = center[0] - v_x[0] * (width / 2) - v_y[0] * (height / 2)

s_y = center[1] - v_x[1] * (width / 2) - v_y[1] * (height / 2)

mapping = np.array([[v_x[0],v_y[0], s_x],

[v_x[1],v_y[1], s_y]])

return cv2.warpAffine(image,mapping,(width, height),flags=cv2.WARP_INVERSE_MAP,borderMode=cv2.BORDER_REPLICATE)

image = cv2.imread('1.jpg')

image = subimage(image, center=(746, 1104), theta=0, width=762, height=428)

#cv2.imwrite('patch.jpg', image)

cv2.imshow('patch.jpg',image)

cv2.waitKey(0)

cv2.destroyAllWindows()

theta:旋转度数,theta=0代表不旋转。

算法原理

发现这个cv2.warpAffine是个很强大的函数, 要扣明白了,找到了CSDN博文:图像的几何变换

很详细了, 就不转了!