When you have a file that ends with .azw or .azw3 it is a Kindle file. To extract the images you will first have to convert the file to an EPUB.

1. Download Calibre
2. Download and install the De-DRM plugin-in for Calibre
3. Open Calibre
4. Select Add books. You'll need to locate the Kindle file on your computer.
5. Once the book is in Calibre, select Convert books
6. Check that the input format states AZW3
7. Select EPUB as the output format
8. Click OK
9. Once the conversion job is complete, you can access the files by highlighting the book in Calibre, right-clicking and selecting Open containing folder
10. You should see an AZW file, a EPUB file, and a metadata file in the folder
11. Now you can extract the images from the EPUB.