Do you still have the site showing in iWeb?
If not then you have to re-type all the text since it got turned into an image there's no way to get the text out of it.
If you still have them in iWeb as described in the Google FAQ:
"iWeb pages are text. BUT if you use custom Fonts, thus not Internet Standard Fonts, those text fields will be converted in an image by iWeb to be sure that people see the texts as you chose.
Yet, again, as long as you use Times, Times New Roman, Helvetica and other Internet standard fonts it's NOT image, IT IS TEXT.
To see which text fields are gonna be turned into images go to File=>Preferences and check the “Show text imaging indicator” box. iWeb is gonna display a yellow picture symbol on the text field. The symbol will not be published to the net."
Hence you should change the formatting of your text so that it doesn't get turned into an image. Also be sure not to have a transparent image or shape in front of the whole page and so on.
Having the text turned into an image is poison for search engines, retrieving text of the published website and more so it should really be avoided.
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