In WordPress 3.0, you can see all attached images or unattached ones. For all attached images, you can also know the post to which the image is attached.
You can start cleaning up by examining unattached images and delete them if necessary.
Thanks Agus.
Will an image be marked as ‘attached’ even if it was uploaded via the media library or ftp?
Or is the ‘attached’ status only given to images that were uploaded via the visual editor on the post/page itself?
Attached status only applicable if the image is uploaded from WordPress media uploader when we are editing the post.
If the image is uploaded using FTP tool, and then referenced manually inside the post, the image status will say unattached. In this case, it is difficult for us to identify whether an image is used in particular post or not.
Hence, we should always use WordPress media uploader when uploading media/image, and make sure it is attached to a post or page.