I'd also add that if the photometry tools haven't actually been written yet, it might be worthwhile to re-visit the idea of having an ```ImageData``` class.   Although we have gone back and forth on this debate, having a ```CCDData``` class has made it much easier to write the code because: a)  we didn't have to specify parameters for every function, b) any checking on what is needed for the object can be done in the ```CCDData``` class instead of repeating in every function, and c) the correct object with the needed properties was always being passed to the functions.  

Of course, we are the only ones to use ccdproc so far, so although it might be easier to code, people may hate using it in that format, but I thought I'd share my experiences so far with ccdproc.