首先，我们需要安装python-docx库和Pillow库。

代码示例：

import os
from docx import Document
from PIL import Image

# 定义一个函数，用于检查文档是否存在图像
def check_for_images(document):
    for image in document.inline_shapes:
        if image.has_image:
            return True
    for image in document.shapes:
        if image.has_image:
            return True
    return False

# 定义一个函数，用于更改图像分辨率
def change_image_resolution(document, dpi):
    for image in document.inline_shapes:
        if image.has_image:
            image_width, image_height = image.width, image.height
            with Image.open(image.image.blob) as im:
                new_image = im.resize((int(image_width/dpi), int(image_height/dpi)))
                image._inline.graphic.graphicData.pic.crop_to(new_image.size)
                image._inline.graphic.graphicData.pic.getchildren()[0].attrib['cy'] = str(new_image.size[1])
                image._inline.graphic.graphicData.pic.getchildren()[0].attrib['cx'] = str(new_image.size[0])
                image._inline.graphic.graphicData.pic.getchildren()[0][0].attrib['cy'] = str(new_image.size[1])
                image._inline.graphic.graphicData.pic.getchildren()[0][0].attrib['cx'] = str(new_image.size[0])

    for image in document.shapes:
        if image.has_image:
            image_width, image_height = image.width, image.height
            with Image.open(image.image.blob) as im:
                new_image = im.resize((int(image_width / dpi), int(image_height / dpi)))
                image.element.getchildren()[0][0].attrib['{http://schemas.openxmlformats.org/drawingml/2006/main}cy'] = str(new_image.size[1])
                image.element.getchildren()[0][0].attrib['{http://schemas.openxmlformats.org/drawingml/2006/main}cx'] = str(new_image.size[0])
                image.element.getchildren()[0][-2].attrib['{http://schemas