june utc you could take your images with a black background and remove it using photoshop or gimp you're probably right about oso although it is possible to show a bit of packing not necessary though molecular structures are mostly about the molecule i respectfully disagree that space filling models are less desirable than ball and stick models graphite intercalation compound is a prime example you can see the way the potassium atoms prop open the graphite layers both styles are complementary although in some cases one may be much clearer thanks for adding the reference to file rutile unit cell d balls png i've updated the image description i think it's important to give the source that was actually used for the image rather than any convenient reference that seems to say the same thing sometimes there are differences or mistakes in sources that we don't notice until later you make a good point about noting atom colours explicitly i will start to do that in my image descriptions it's not always practical though to add a caption chemboxes are a notable example and often it is easy to deduce which atom is which colour e g phosphorus pentafluoride