I noticed on
- MaskedImage is missing the parameters that all other image-like StorageClasses have (I'm pretty sure its FITS formatter does support them).
- MaskedImage is missing components (maybe its FITS formatter can handle them? It's hard to say).
- Things like Image and Mask that don't have components are declared with ExposureAssembler, which looks to me like it's not actually for anything other than Exposure. And MaskedImage probably should get an assembler if it gets components.