I'm looking for a cross-platform library that gives me a convenient API for reading/writing popular image formats. I don't think I'll need any image processing functions (like filters), but if the best library happens to come with those, it's not an issue.

Since I intend to convert input images to an internal single-channel floating-point format, an API with a generic interface to different underlying formats would be nice.

I've found the following promising candidates:

Any suggestions / experiences welcome.