Dear Ged,
I'm a little confused here.
The glmax field in an Analyze image doesn't have a concrete definition
and is often unrelated to the actual range of intensity values contained
in the image. Do you know what the range of values are that are contained
in the raw file (unscaled) - easily obtained using avwstats - versus the
range of values that SPM uses (scaled)?
All the best,
Mark
Ged Ridgway wrote:
> Mark Jenkinson wrote:
>
>> So I recommend checking the funused fields (you can look at the
>> output of avwhd) and if they are zeros then you can proceed without
>> problem.
>
>
> Actually I'm afraid it gets worse... I have Analyze images (I think
> produced from SPM99) that include a scale-factor which doesn't show up
> in these fields...
>
> SPM5 shows the images as having intensity from 0 to 1, while avwhd
> shows all (unused1, funused1, funused2, funused3) as zero, with the
> glmax as 32767 -- so perhaps you need to scale by this in some
> situations? Try asking on the SPM list if that is where your images
> originate.
>
> Best of luck,
> Ged.
