Of course a proper Image SEO starts with the right name. Without even looking at the actual image, you want search engines to know what the image is about. Since the standard value used by THRON to generate URLs is the contentId, you might want to change such parameter with a more describing keyword. This can be done via prettyId, and you can even set one keyword for each available language.
It’s simple: if your image is about a running dog, the file name shouldn’t be an alphanumeric code like the contentId or a file name; it should rather be something like "running-dog".
In order to update the prettyId of a content you must invoke the updateContentPrettyId web service. Write access right is required on the content to perform this action.