[Insight-users] Question about image origin

[Somer, Edward]

In reply to myself: Visually it appears a translation of (outSpacing - 
inSpacing)/2.0 is required, but this may be due to the display software 
which I'm trying to evaluate...

Somer, Edward wrote:
> Hi,
>
> I have a 1000x1000 image with a spacing of 0.5\0.5 and I wish to 
> resample it to 125x125 with spacing 4.0\4.0 but I wish the centre of 
> each field of view to be coincident. On writing the data my "Image 
> Position (Patient)" goes from 249.75\249.75 to 248.0\248.0, being the 
> centre of the top left pixel.
>
> If I set the input and output origin to 0.0\0.0 are the FoV aligned or 
> should I set the input origin to 0.25/0.25 and the output origin to 
> 2.0/2.0? Looking at the manual the origin at 0.0\0.0 looks like it's at 
> the centre of the 0th pixel but if I resize the pixels the centre of the 
> pixel (hence the origin) will move.
>
> I'm trying to evaluate display image alignment so it needs to be as 
> accurate as possible.
>
> Thanks,
>
> Ed
>
>   


-- 
Edward Somer, PhD.
Senior PET Methodologist
The PET Imaging Centre 
St Thomas' Hospital
London, UK
SE1 7EH

work tel: +44 (0) 20 7188 1497
work fax: +44 (0) 20 7620 0790
e-mail: Edward.Somer at kcl.ac.uk / Edward.Somer at googlemail.com