实现针对同一张图片缩放，裁剪、补边和仿射等变换。

import cv2
 

img = cv2.imread('C:/Users/xpp/Desktop/time2.jpg')
 

img_200x200 = cv2.resize(img, (200, 200))
 
img_200x300 = cv2.resize(img, (0, 0), fx=0.5, fy=0.5, 
                              interpolation=cv2.INTER_NEAREST)

img_300x300 = cv2.copyMakeBorder(img, 50, 50, 0, 0, 
                                       cv2.BORDER_CONSTANT, 
                                       value=(0, 0, 0))

patch_tree = img[20:150, -180:-50]
 
cv2.imwrite('cropped_tree.jpg', patch_tree)
cv2.imwrite('resized_200x200.jpg', img_200x200)
cv2.imwrite('resized_200x300.jpg', img_200x300)
cv2.imwrite('bordered_300x300.jpg', img_300x300)

img_hsv = cv2.cvtColor(img, cv2.COLOR_BGR2HSV)
 
turn_green_hsv = img_hsv.copy()
turn_green_hsv[:, :, 0] = (turn_green_hsv[:, :, 0]+15) % 180
turn_green_img = cv2.cvtColor(turn_green_hsv, cv2.COLOR_HSV2BGR)
cv2.imwrite('turn_green.jpg', turn_green_img)

colorless_hsv = img_hsv.copy()
colorless_hsv[:, :, 1] = 0.5 * colorless_hsv[:, :, 1]
colorless_img = cv2.cvtColor(colorless_hsv, cv2.COLOR_HSV2BGR)
cv2.imwrite('colorless.jpg', colorless_img)

darker_hsv = img_hsv.copy()
darker_hsv[:, :, 2] = 0.5 * darker_hsv[:, :, 2]
darker_img = cv2.cvtColor(darker_hsv, cv2.COLOR_HSV2BGR)
cv2.imwrite('darker.jpg', darker_img)

import cv2
import numpy as np
 

img = cv2.imread('C:/Users/xpp/Desktop/time2.jpg')

M_crop_elephant = np.array([
    [1.6, 0, -150],
    [0, 1.6, -240]
], dtype=np.float32)
 
img_elephant = cv2.warpAffine(img, M_crop_elephant, (400, 600))
cv2.imwrite('lanka_elephant.jpg', img_elephant)

theta = 15 * np.pi / 180
M_shear = np.array([
    [1, np.tan(theta), 0],
    [0, 1, 0]
], dtype=np.float32)
 
img_sheared = cv2.warpAffine(img, M_shear, (400, 600))
cv2.imwrite('lanka_safari_sheared.jpg', img_sheared)

M_rotate = np.array([
    [np.cos(theta), -np.sin(theta), 0],
    [np.sin(theta), np.cos(theta), 0]
], dtype=np.float32)
 
img_rotated = cv2.warpAffine(img, M_rotate, (400, 600))
cv2.imwrite('lanka_safari_rotated.jpg', img_rotated)
 
M = np.array([
    [1, 1.5, -400],
    [0.5, 2, -100]
], dtype=np.float32)
 
img_transformed = cv2.warpAffine(img, M, (400, 600))
cv2.imwrite('lanka_safari_transformed.jpg', img_transformed)