[Insight-developers] Should Filters propogate the Direction Cosines from Image input to image output?

[Kent Williams]

I discovered this when using ResampleImageFilter to shrink some image 
volumes -- the ResampleImageFilter doesn't propogate the Direction 
Cosines from the input image into the output image. Consequently if you 
write out the resulting image it may not be oriented consistent with the 
input image.

Should filters set the Direction Cosines on the output? I know that 
itk::OrientImageFilter does so, which is natural since it is changing 
the orientation. But what about filters like ResampleImageFilter, which 
does not change the image orientation?  What about the cases where an 
output image is produced from more than one input image?