Question about setting up multiple relations

Hi, I have an Image table in a MySQL database that will be used to store the location of all images used on my site. Some images will relate to an Article table (article.id) and some images may relate to a Member table (member.id). As it's possible that there may be an article.id that is the same as a member.id, I am considering adding two fields to the Image table (article_id and member_id) one of which will be left blank for each record, depending on the image's relation. For example, if "mypic.jpg" is related to article.id 288 in the Article table, then I would insert 288 into the article_id field in the Image table but leave the member_id field blank. Is this kosher, or is there a better way to do this? Thanks!