你可以合并PIL的Image。带有sys的缩略图。如果您的调整大小限制仅在一个维度(宽度或高度)上，请使用Maxsize。

例如，如果你想调整图像的大小，使其高度不超过100px，同时保持纵横比，你可以这样做:

import sys
from PIL import Image

image.thumbnail([sys.maxsize, 100], Image.ANTIALIAS)

记住这个形象。thumbnail将调整图像的大小，这与image不同。Resize，而不是返回调整后的图像，而不改变原始图像。

编辑:形象。ANTIALIAS会发出弃用警告，并将在PIL 10(2023年7月)中删除。相反，你应该使用重采样。兰索斯:

import sys
from PIL import Image
from PIL.Image import Resampling

image.thumbnail([sys.maxsize, 100], Resampling.LANCZOS)

举个丑陋的例子。

函数获取像pic[0-9a-z]这样的文件。[扩展]"，将它们调整为120x120，移动部分到中心，并保存到"ico[0-9a-z]。[扩展]”，肖像和风景作品:

def imageResize(filepath):
    from PIL import Image
    file_dir=os.path.split(filepath)
    img = Image.open(filepath)

    if img.size[0] > img.size[1]:
        aspect = img.size[1]/120
        new_size = (img.size[0]/aspect, 120)
    else:
        aspect = img.size[0]/120
        new_size = (120, img.size[1]/aspect)
    img.resize(new_size).save(file_dir[0]+'/ico'+file_dir[1][3:])
    img = Image.open(file_dir[0]+'/ico'+file_dir[1][3:])

    if img.size[0] > img.size[1]:
        new_img = img.crop( (
            (((img.size[0])-120)/2),
            0,
            120+(((img.size[0])-120)/2),
            120
        ) )
    else:
        new_img = img.crop( (
            0,
            (((img.size[1])-120)/2),
            120,
            120+(((img.size[1])-120)/2)
        ) )

    new_img.save(file_dir[0]+'/ico'+file_dir[1][3:])

一个简单的方法，保持约束比率和通过最大宽度/高度。不是最漂亮的，但可以完成工作，而且很容易理解:

def resize(img_path, max_px_size, output_folder):
    with Image.open(img_path) as img:
        width_0, height_0 = img.size
        out_f_name = os.path.split(img_path)[-1]
        out_f_path = os.path.join(output_folder, out_f_name)

        if max((width_0, height_0)) <= max_px_size:
            print('writing {} to disk (no change from original)'.format(out_f_path))
            img.save(out_f_path)
            return

        if width_0 > height_0:
            wpercent = max_px_size / float(width_0)
            hsize = int(float(height_0) * float(wpercent))
            img = img.resize((max_px_size, hsize), Image.ANTIALIAS)
            print('writing {} to disk'.format(out_f_path))
            img.save(out_f_path)
            return

        if width_0 < height_0:
            hpercent = max_px_size / float(height_0)
            wsize = int(float(width_0) * float(hpercent))
            img = img.resize((max_px_size, wsize), Image.ANTIALIAS)
            print('writing {} to disk'.format(out_f_path))
            img.save(out_f_path)
            return

下面是一个python脚本，使用这个函数来运行批量图像调整。

我用这种方法调整了图像的大小，效果很好

from io import BytesIO
from django.core.files.uploadedfile import InMemoryUploadedFile
import os, sys
from PIL import Image


def imageResize(image):
    outputIoStream = BytesIO()
    imageTemproaryResized = imageTemproary.resize( (1920,1080), Image.ANTIALIAS) 
    imageTemproaryResized.save(outputIoStream , format='PNG', quality='10') 
    outputIoStream.seek(0)
    uploadedImage = InMemoryUploadedFile(outputIoStream,'ImageField', "%s.jpg" % image.name.split('.')[0], 'image/jpeg', sys.getsizeof(outputIoStream), None)

    ## For upload local folder
    fs = FileSystemStorage()
    filename = fs.save(uploadedImage.name, uploadedImage)

已经更新了上面的答案“tomvon”

from PIL import Image

img = Image.open(image_path)

width, height = img.size[:2]

if height > width:
    baseheight = 64
    hpercent = (baseheight/float(img.size[1]))
    wsize = int((float(img.size[0])*float(hpercent)))
    img = img.resize((wsize, baseheight), Image.ANTIALIAS)
    img.save('resized.jpg')
else:
    basewidth = 64
    wpercent = (basewidth/float(img.size[0]))
    hsize = int((float(img.size[1])*float(wpercent)))
    img = img.resize((basewidth,hsize), Image.ANTIALIAS)
    img.save('resized.jpg')

我还将添加一个调整大小的版本，以保持纵横比固定。 在本例中，它将根据初始宽高比asp_rat (float(!))调整高度以匹配新图像的宽度。 但是，要调整宽与高，只需在else循环中注释一行，取消注释另一行。你会看到，在哪里。

你不需要分号(;)，我保留它们只是为了提醒自己我经常使用的语言的语法。

from PIL import Image

img_path = "filename.png";
img = Image.open(img_path);     # puts our image to the buffer of the PIL.Image object

width, height = img.size;
asp_rat = width/height;

# Enter new width (in pixels)
new_width = 50;

# Enter new height (in pixels)
new_height = 54;

new_rat = new_width/new_height;

if (new_rat == asp_rat):
    img = img.resize((new_width, new_height), Image.ANTIALIAS); 

# adjusts the height to match the width
# NOTE: if you want to adjust the width to the height, instead -> 
# uncomment the second line (new_width) and comment the first one (new_height)
else:
    new_height = round(new_width / asp_rat);
    #new_width = round(new_height * asp_rat);
    img = img.resize((new_width, new_height), Image.ANTIALIAS);

# usage: resize((x,y), resample)
# resample filter -> PIL.Image.BILINEAR, PIL.Image.NEAREST (default), PIL.Image.BICUBIC, etc..
# https://pillow.readthedocs.io/en/3.1.x/reference/Image.html#PIL.Image.Image.resize

# Enter the name under which you would like to save the new image
img.save("outputname.png");

这样就完成了。我尽我所能记录下来，所以很清楚。

我希望这对外面的人有所帮助!