【python 工具】图片缩放 pil/cv

# 从文件中读取图片，然后 resize 大小：
import matplotlib.pyplot as plt
import numpy as np
from PIL import Image

img=Image.open(r"1.jpg")
print("原图的height，weight分别为：", np.asarray(img).shape[:2])
plt.imshow(np.asarray(img))
plt.show()

height, weight = (np.asarray(img).shape)[:2]
height = height//10
weight = weight//10
img2 = Image.Image.resize(img, (weight, height))
print("resized后图的height，weight分别为：", np.asarray(img2).shape[:2])
plt.imshow(np.asarray(img2))
plt.show()

# 从字节码（Bytes）中读取图片，然后 resize 大小：
import matplotlib.pyplot as plt
import numpy as np
from PIL import Image
from io import BytesIO


img = open("1.jpg", "rb").read()   #读取序列化的二进制码
img = BytesIO( img )
img = Image.open( img )
print("原图的height，weight分别为：", np.asarray(img).shape[:2])
plt.imshow(np.asarray(img))
plt.show()

height, weight = (np.asarray(img).shape)[:2]
height = height//10
weight = weight//10
img2 = Image.Image.resize(img, (weight, height))
print("resized后图的height，weight分别为：", np.asarray(img2).shape[:2])
plt.imshow(np.asarray(img2))
plt.show()

# cv2.IMREAD_COLOR：加载彩色图像。图像的任何透明度都将被忽略。这是默认标志。 flags=1
# cv2.IMREAD_GRAYSCALE：以灰度模式加载图像 flags=0
# cv2.IMREAD_UNCHANGED：加载包含Alpha通道的图像 flags=-1

import matplotlib.pyplot as plt
import numpy as np
import cv2
# rgb图
img=cv2.imread(r"1.jpg", 1)
# 灰度图
#img=cv2.imread(r"1.jpg", 0)

print("原图的height，weight分别为：", np.asarray(img).shape[:2])
#plt.imshow(np.asarray(img))
#plt.show()
cv2.imshow("img", mat=img)
cv2.waitKey (0)


height, weight = (img.shape)[:2]
height = height//3
weight = weight//3
img2 = cv2.resize(img, (weight, height))
print("resized后图的height，weight分别为：", img2.shape[:2])
#plt.imshow(np.asarray(img2))
#plt.show()
cv2.imshow("img2", mat=img2)
cv2.waitKey (0)
cv2.destroyAllWindows()

# 读取图片， matplotlib展示图片： 把cv2的bgr转换为rgb，然后展示。 [...,::-1]
import matplotlib.pyplot as plt
import numpy as np
import cv2
# rgb图
img=cv2.imread(r"1.jpg", 1)
# 灰度图
#img=cv2.imread(r"1.jpg", 0)

print("原图的height，weight分别为：", np.asarray(img).shape[:2])
plt.imshow(np.asarray(img)[...,::-1])
plt.show()


height, weight = (img.shape)[:2]
height = height//3
weight = weight//3
img2 = cv2.resize(img, (weight, height))
print("resized后图的height，weight分别为：", img2.shape[:2])
plt.imshow(np.asarray(img2)[...,::-1])
plt.show()