[Insight-developers] astronomy images, SpecialCoordinatesImage and ImageIO

[Michael Halle]

Hello,

I'm part of the team working to get FITS astronomy images into ITK. 
During the last programmer's week, Doug Alan got volume reading 
completed;  now we're working on quantitative information.

I've hit a code structuring issue and I'd like some advice.  FITS images 
have potentially complex physical to index transforms, and we have a 
library that will take care of those transforms for us.  So, we need to 
use an image that allows us direct access to the methods like 
TransformIndexToPhysicalPoint and their inverses.

It looks like a SpecialCoordinatesImage is a good base class for this 
type of image, since these Transform* methods are the only ones left 
abstract.

The problem is that if we implement the Transform* methods in a subclass 
of SpecialCoordinatesImage, we're specializing both the ImageIOBase 
subclass and the ImageBase subclass to be able to read FITS files.

It seems like it would be nice to contain the FITS-specific information 
in a subclass of ImageIOBase, and have a concrete subclass of 
itkSpecialCoordinatesImage just use the Transform* information it gets 
from this class.

So, should we just take the simple approach and create both FITSImage 
and FITSImageIO classes, or look at the cleaner but more complex approach?

Thanks for any advice....

Michael Halle
Surgical Planning Lab / Harvard IIC