Say a development team includes (or makes use of) graphic artists who create all the images that go into a product. Such things include icons, bitmaps, window backgrounds,
We, too, just put the binaries in source control. We use Git, but it would apply just as well to Subversion.
One suggestion I have is to use SVGs where possible, because you can see actual differences. With binaries (most other image formats), the best you can get is a version history.
@lomaxx TortoiseSVN includes a program called TortoiseIDiff which looks to be a diff for images. I haven't used it but looks intriguing.
GitHub recently introduced "image view modes", take a look: https://github.com/blog/817-behold-image-view-modes.