Improve accessibility by replace the default alt- and title-attributes

Is there any possibility to replace the default alt-attribute (img) and title-attribute of links to items. I would like to add a description of the image (not the title of the item) in the alt-attribute of the image and the title-attribute (href) that is default to any links to items

The alt for images should be settable by making a Title for the File, rather than the Item.

I don't think there's a field that automatically corresponds to a link's title, though.