AFAIK, these are the most recent published guidelines, but reading the forums, it seems that changes are often made before the relevant info is updated. If you don't feel like your images are covered in the article, you'd need to contact them. Also check out their forums, they're not heavily posted to, so not too onerous.
https://contributors.gettyimages.com/article.aspx?article_id=4837&esource=2016_12_13_iStock_NL_em_SEG