import os
from PIL import Image
 
def compress_image(infile, outfile='', kb=80, step=10, quality=80):
    """不改变图片尺寸压缩到指定大小
    :param infile: 压缩源文件
    :param outfile: 压缩文件保存地址
    :param kb: 压缩目标, KB
    :param step: 每次调整的压缩比率
    :param quality: 初始压缩比率
    :return: 压缩文件地址，压缩文件大小
    """
    o_size = os.path.getsize(infile)/1024
    if o_size <= kb:
        return infile
    if outfile == '':
        outfile = infile
    while o_size > kb:
        im = Image.open(infile)
        im.save(outfile, quality=quality)
        if quality - step < 0:
            break
        quality -= step
        o_size = os.path.getsize(outfile)/1024
    return outfile, o_size