python批量resize图片大小_python 批量图片resize代码——分别3种库函数实现

一.1.opencv:      cv2

'cv2'

import cv2

import os

import glob

path = r'C:\Users\87419\Desktop\cg1\img\*.jpg'

for i in glob.glob(path):

im1 = cv2.imread(i)

im2 = cv2.resize(im1,(256,256))

cv2.imwrite(os.path.join(r'C:\Users\87419\Desktop\cg1\resize',os.path.basename(i)),im2)

2.matplotlib ：  from matplotlib import pyplot as plt

'plt, PIL '

'plt本身无法实现resize， 故不推荐此方法(得到的图是带白边的)'

import matplotlib.pyplot as plt

import os

import glob

from PIL import Image

path = r'C:\Users\87419\Desktop\cg1\img\*.jpg'

for i in glob.glob(path):

im1 = Image.open(i)

im2 = im1.resize((256,256))

plt.imshow(im2)

plt.axis('off')

plt.savefig(os.path.join(r'C:\Users\87419\Desktop\cg1\resize',os.path.basename(i)))

3. PIL：  from PIL import Image

'PIL'

from PIL import Image

import os

import glob

path = r'C:\Users\87419\Desktop\cg1\img\*.jpg'

for i in glob.glob(path):

im1 = Image.open(i)

im2 = im1.resize((256,256))

im2.save(os.path.join(r'C:\Users\87419\Desktop\cg1\resize',os.path.basename(i)))

可能会遇到报错 OSError: cannot write mode P as JPEG

解决方法  如下(其余格式报错同理，按 if img.mode == "P" or img.mode == "RGBA":  统一转为RGB就可以了)

import os

from PIL import Image

def resize_image():

# 获取输入文件夹中的所有文件

files = os.listdir(r'C:\Users\admin\Desktop\drone\beijing')

output_dir = r'C:\Users\admin\Desktop\drone\bj_416'

if not os.path.exists(output_dir):

os.makedirs(output_dir)

for file in files:

img = Image.open(r'C:\Users\admin\Desktop\drone\beijing/' + file)

if img.mode == "P" or img.mode == "RGBA":

img = img.convert('RGB')

img = img.resize((416, 416), Image.ANTIALIAS)

img.save(os.path.join(output_dir, file))

resize_image()

详解见  https://blog.csdn.net/z704630835/article/details/84968767

二.按指定图像位置裁剪

以按中心位置抠出128*128大小为例：

先

import os

import cv2

# 遍历指定目录，显示目录下的所有文件名

def CropImage4File(filepath, destpath):

pathDir = os.listdir(filepath) # list all the path or file in filepath

for allDir in pathDir:

child = os.path.join(filepath, allDir)

dest = os.path.join(destpath, allDir)

if os.path.isfile(child):

image = cv2.imread(child)

sp = image.shape # obtain the image shape

sz1 = sp[0] # height(rows) of image

sz2 = sp[1] # width(colums) of image

a = int(sz1 / 2 - 600) # x start

b = int(sz1 / 2 + 300) # x end

c = int(sz2 / 2 - 450) # y start

d = int(sz2 / 2 + 450) # y end

cropImg = image[a:b, c:d] # crop the image

cv2.imwrite(dest, cropImg) # write in destination path

if __name__ == '__main__':

filepath = r'C:\Users\admin\Desktop\1\01' # source images

destpath = r'C:\Users\admin\Desktop\1\02' # resized images saved here

CropImage4File(filepath, destpath)

再

'cv2'

import cv2

import os

import glob

path = r'C:\Users\admin\Desktop\1\02\*.jpg'

for i in glob.glob(path):

im1 = cv2.imread(i)

im2 = cv2.resize(im1, (128, 128))

cv2.imwrite(os.path.join(r'C:\Users\admin\Desktop\1\r_128', os.path.basename(i)), im2)