批量放縮

（1） 等比例放縮

from PIL import Image
import os
scale = 1.0/3

cnt=1
source_path=r"C:\Users\HD"
result_path=r"C:\Users\tresult"
files = os.listdir(source_path)
files.sort(key=lambda x: int(x.split('.')[0]))
for file in  files:
    img = Image.open(os.path.join(source_path,file))
    width = int(img.size[0] * scale)
    height = int(img.size[1] * scale)
    img_resize = img.resize((width,height),Image.ANTIALIAS)
    img_resize.save(os.path.join(result_path,"%d.png" %cnt))
    cnt = cnt+1

（2）放縮爲指定大小（裁剪）
 

from PIL import Image
import os
cnt = 0
source_path=r"C:\Users\Desktop\Urban100"
result_path=r"C:\Users\Desktop\Urban100"
files = os.listdir(source_path)
files.sort(key=lambda x: str(x.split('.')[0]))
for file in  files:
    img = Image.open(os.path.join(source_path,file))
    width = int(img.size[0])
    height = int(img.size[1])
    if width%3==1:
        width = width-1
    if width%3==2:
        width = width-2
    if height%3==1:
        height = height-1
    if height%3==2:
        height = height-2
    img_resize = img.resize((width,height),Image.ANTIALIAS)
    img_resize.save(os.path.join(result_path,"%d.png" %cnt))
    cnt = cnt + 1