如果你不想/不需要用Pillow打开图像，使用这个:

from PIL import Image

new_img_arr = numpy.array(Image.fromarray(img_arr).resize((new_width, new_height), Image.ANTIALIAS))

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')

定义最大大小。 然后，通过取min(maxwidth/width, maxheight/height)来计算调整大小的比率。

合适的尺寸是旧尺寸*比例。

当然，还有一个库方法可以做到这一点:Image.thumbnail方法。 下面是来自PIL文档的一个(编辑过的)示例。

import os, sys
import Image

size = 128, 128

for infile in sys.argv[1:]:
    outfile = os.path.splitext(infile)[0] + ".thumbnail"
    if infile != outfile:
        try:
            im = Image.open(infile)
            im.thumbnail(size, Image.Resampling.LANCZOS)
            im.save(outfile, "JPEG")
        except IOError:
            print "cannot create thumbnail for '%s'" % infile

######get resize coordinate after resize the image using this function#####
def scale_img_pixel(points,original_dim,resize_dim):
        multi_list = [points]
        new_point_list = []
        multi_list_point = []
        for point in multi_list:
            multi_list_point.append([point[0],point[1]])
            multi_list_point.append([point[2],point[3]])
        for lsingle_point in multi_list_point:
            x1 = int((lsingle_point[0] * (resize_dim[0] / original_dim[0])))
            y1 = int((lsingle_point[1] * (resize_dim[1] / original_dim[1])))
            new_point_list.append(x1)
            new_point_list.append(y1)
            
        return new_point_list
    
    
    points = [774,265,909,409]
    original_dim = (1237,1036)
    resize_dim = (640,480)
    result = scale_img_pixel(points,original_dim,resize_dim)
    print("result: ", result)  

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:])

如果你不想/不需要用Pillow打开图像，使用这个:

from PIL import Image

new_img_arr = numpy.array(Image.fromarray(img_arr).resize((new_width, new_height), Image.ANTIALIAS))