[人工智能]图片双线性插值旋转任意角度（python）

看了很多文章都不完整，结合一下写了完整版

import numpy as np
import cv2
import math
import random
#双线性旋转
def bilinear_rotate(imgArray,theta):
    H, W, channel = imgArray.shape

    pi = math.pi
    #theta = random.randint(0,360)
    angle = theta * pi / 180

    matrix1 = np.array([[1, 0, 0],
                        [0, -1, 0],
                        [-0.5 * H, 0.5 * W, 1]])

    matrix2 = np.array([[math.cos(angle), -math.sin(angle), 0],
                        [math.sin(angle), math.cos(angle), 0],
                        [0, 0, 1]])

    matrix3 = np.array([[1, 0, 0],
                        [0, -1, 0],
                        [0.5 * H, 0.5 * W, 1]])

    new_data = np.zeros_like(imgArray,dtype=np.uint8)

    for i in range(H):
        for j in range(W):

            dot1 = np.matmul(np.array([i, j, 1]), matrix1)
            dot2 = np.matmul(dot1, matrix2)
            dot3 = np.matmul(dot2, matrix3)

            new_coordinate = dot3

            new_i = int(math.floor(new_coordinate[0]))
            new_j = int(math.floor(new_coordinate[1]))

            u = new_coordinate[0] - new_i
            v = new_coordinate[1] - new_j

            if new_j>=W or new_i >=H or new_i<1 or new_j<1 or (i+1)>=H or (j+1)>=W:
                continue

            if (new_i + 1)>=H or (new_j+1)>=W:
                new_data[i, j, :] = imgArray[new_i,new_j, :]

            else:
                new_data[i, j, :] = (1-u)*(1-v)*imgArray[new_i,new_j, :] + \
                                   (1-u)*v*imgArray[new_i,new_j+1, :] + \
                                   u*(1-v)*imgArray[new_i+1,new_j, :] +\
                                   u*v*imgArray[new_i+1,new_j+1, :]

    return new_data
def ratate(theta):
	imgdata = cv2.imread('test.jpg')
	cv2.imwrite('ans.jpg',bilinear_rotate(imgdata,theta))
	ans = cv2.imread('ans.jpg')
	cv2.imshow('旋转结果',ans)
	cv2.waitKey(0)
if __name__ == '__main__':
	ratate(180)