Downloading an image that's embedded in a Google Docs file isn't a straightforward process, but it's definitely possible. If someone's sent you a doc but forgot to attach the images separately, and you need to get a photo or two out, here are a few ways to extract the images you need.
Download the file as an HTML document
The simplest and most effective way to extract embedded images from Google Docs is to save the document as an HTML file. To do this, go to File > Download > Web page and save the file to your computer. When you open the file, you'll find a folder called images, which will have all of the photos embedded in the Google Docs file.
Save images to Google Keep
You can also save any image from a Google Docs file to Google Keep. To do this, right-click the photo you want to extract, and select View more actions > Save to Keep. This will open the image in the right pane. You can right-click its thumbnail and select Save Image As to download the photo.
Publish the document to the web
Google Docs allows you to publish your document to the web. You can use this to extract any photos embedded in the file. Then you can open the published file, right-click any image, and select Save Image As to save it.
Use the good old screenshot method
In case all else fails because you don't have an internet connection, you can quickly take a screenshot of any of the photos in the Google Doc. Before taking a screenshot, zoom into any file until a point where the images look reasonably high-quality. This will allow you to capture a slightly larger image, if the embedded file appears a little smaller than what you need.