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!