@jfirebaugh I've added an Impl to style::Image according to #8820 (comment). I kept the SpriteAtlas intact instead of adding the image collection directly on Style like you've suggested in #8820 (comment). Thought that might be a bit more nicely encapsulated, but I can change that if you prefer.

Yes, I think it's better to add the image collection directly on Style. The main reason is that we want to make style images more like sources and layers -- a collection of items held by the style, which you can add to and remove from. Separately, "atlas" is a rendering-specific concept: a single texture which can be indexed into by vertex attributes in order to render individual images.