Process to convert to actual jpeg files

I am downloading JPEG images off an AWS server using SEO Tools download formula. The target server is to be shut down. I need to preserve the images in their entirety independent of the server.
It appears the image files produced by SEO tools are images of the existing files and are therefore dependant on the original images. They are not jpeg files in their own right. What is the process to convert these to actual independent images / fully formed ".jpeg" files? - can you point me somewhere or correct me if I am wrong.

SeoTools for Excel do not have support for image converting. I would recommend downloading the images then using an external tool for converting to jpeg.