Dear All,

I understand the reason behind pform_code and sform_code. However, I think its implementation can be improved.

I think use of two different forms, and the fact that both can coesxist complicate works seriously for me. Alllowing user to specify only one save me a lot of trouble. I still yet to see a program that needs both, but have to admit I proabably did not see the full picture of NifTI usage.

And while I can see the restriction on sform_code compared to pform_code, I cannot exactly why sform_code  cannot be store as 3x4 matrix. That makes reading the transformation matrix easier for us joe user.

Frankly, it is easy to reverse engineer 3x4 transformation matrix to sform format. nifticlib even conveniently  gives you a  function to do that. IMHO any worry about the sform cofficients not being exact after the transformation is misplaced. If your coefficients are sensitive to 8 s.f. then probably you should start asking question about your algorithm. Furthermore, in NifTI 2 we are using double datatype, not float to represent the data. Therefore, the problem with imprecise coef is reduced.

Perhaps this should be seen as a plea from users like me who have to constantly worry about whether I should transform from sform code to pform code, whether if both are present, they are referring to the same thing and if they don't, what am I to do?

Thanks
Cinly