Interaction of Wysiwyg and Input Filters

Can you please explain how this works, since I am confused?

I understood that information entered into a text field was written directly to the database, and then passed through the Input Filter when the page was subsequently viewed.

However, I have finally worked out that when using Wysiwyg plus an editor, the Filter settings change what is written to the database when the page is saved. In fact it happens before the page is saved, since if I examine the HTML using the editor's "Source Code" button the style attributes concerned (in this case attributes on the table tag) have disappeared; even though they are being displayed on the screen at the time.

I believe that this occurs in the Wysiwyg module, since I get the same effect with two different editors.

Can you confirm that my understanding is now correct, or give a reference to a more detailed explanation?

With thanks,
Tony Maynard-Smith.