好的，我自己拍的照片，在这里：

zY28f_64.png,zY28f_80.png,zY28f_96.png

以代码结束：

from PIL import Image,ImageOps
import os



path= 'images'

x = 0
for dirname,dirs,files in os.walk(path):
    for filename in files:
        x+=1
        path = dirname + "/" + filename
        print(path)
        
        im = Image.open(path)
        
        im.show()
        
        fill_color = (255,255,255)
        im = im.convert("RGBA")
        if im.mode in ('RGBA','LA'):
            background = Image.new(im.mode[:-1],im.size,fill_color)
            # background.paste(im,im.split()[-1])
            background.paste(im)
            im = background
        im_inv = ImageOps.invert(im)   ### make white background black
        imResize = ImageOps.fit(im.crop(im_inv.getbbox()),(96,96),Image.BOX,(0.5,0.5))  # im.crop crop on box got from image with black background,Image.getbbox works only with black bacground returning biggest box containing non zero(non black ) pixels
        
        imResize.show()
        
        # imResize.save("dataset/images/" + str(x) + '.png','PNG')

输出：

zY28f_64.png2.png,zY28f_80.png1.png,zY28f_96.png3.png

这里的主要变化：

使白底变黑

im_inv = ImageOps.invert(im)

从黑色背景图像获得的框上的 im.crop 裁剪，Image.getbbox 仅适用于黑色背景，返回包含非零（非黑色）像素的最大框

imResize = ImageOps.fit(im.crop(im_inv.getbbox()),0.5))

由于 ImageOps.fit(...) 行返回切碎的图像，不确定它是如何工作的，为了保留整个数字，我使用 PIL Image.resize() not resizing the picture 中的代码获取：

from PIL import Image,ImageOps
import os
import math


path= 'images'

x = 0
for dirname,files in os.walk(path):
    for filename in files:
        x+=1
        path = dirname + "/" + filename
        print(path)
        
        im = Image.open(path)
        

        
        fill_color = (255,im.split()[-1])
            background.paste(im)
            im = background
        im_inv = ImageOps.invert(im)
        
        imResize = im.crop(im_inv.getbbox())
        
        width,height = imResize.size
        print(width,height)
        if height > width:
            ratio = math.floor(height / width)
            newheight = ratio * 96
            print(imResize,ratio,newheight)
            imResize = imResize.resize((96,newheight))
        else:
            ratio = math.floor(width /height )
            newwidth = ratio * 96
            print(imResize,newwidth)
            imResize = imResize.resize((newwidth,96))
        

        
        imResize.show()
        print(imResize.size)
        
        imResize.save(path + str(x) + '.png','PNG')

输出：

zY28f_64.png2.png,zY28f_96.png3.png