Mark Jenkinson wrote:
> 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)?
Hope the following helps:
avwstats img -R
0.000000 28735.000000
avwhd img | grep glmax
glmax 32767
avwhd img | grep unused
unused1 0
funused1 0.0000
funused2 0.0000
funused3 0.0000
SPM5 display:
Intensity Y = 3.0515e-05 X
Max, taken roughly from display (can't see a sensible way of getting
the stats from spm5, or even loading the volume into a matrix)
0.9 so roughly consistent with 28735*3.0515e-05
Random notes, 1/(3.0515e-05) is roughly 32771 rather than 32767...
32767 is of course the max value for signed int16 (2^15-1), I'm very
confused...
Mark, can you try asking on the SPM mailing list?
Best,
Ged.
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