Hi,
I'm still not sure you have a problem. How are you judging that the
intensity is decreased?
Cheers.
On 22 Jan 2008, at 06:28, Li Jiang wrote:
> Hi,
>
> Thank you very much. I still have a question. The original subject
> image is epi sequence.After I transform this image to highres T1 image
> and then to MNI-space, the intensity of the transformed sub2mni image
> decreased compare to the original epi image. When transform, I use
> trilinear interpolation and cost function is correlation ratio. How
> can I improve this problem? Which interpolation method and cost
> function should I apply?
>
> Li
>
> 2008/1/21, Steve Smith <[log in to unmask]>:
>> Hi,
>>
>> avscale gives you a whole set of different pieces of information
>> about
>> the spatial affine transform, including the average scaling (size)
>> change. It does not tell you anything about intensities. On average,
>> in general, intensities don't change upon resampling, though of
>> course
>> any given voxel will change!
>>
>> Cheers.
>>
>>
>> On 19 Jan 2008, at 15:12, Li Jiang wrote:
>>
>>> Dear Steve Smith,
>>>
>>> I use fsl to process the functional MR data. It is a great software.
>>> To process the data, I first transform the EPI (subject image) data
>>> to T1 volume then to MNI_space with affine transformation. And I'll
>>> measure the absolute value from the images have been coregistered to
>>> MNI-space . I learned from the lectures and noticed the avscale for
>>> Inter-subject Registration. I wonder what's the scale mean. If the
>>> signal intensity of the subject image will change after affine
>>> transformation or global intra-subject transformation.
>>>
>>>
>>>
>>> Best regards.
>>>
>>> Li Jiang
>>>
>>
>>
>> ---------------------------------------------------------------------------
>> Stephen M. Smith, Professor of Biomedical Engineering
>> Associate Director, Oxford University FMRIB Centre
>>
>> FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK
>> +44 (0) 1865 222726 (fax 222717)
>> [log in to unmask] http://www.fmrib.ox.ac.uk/~steve
>> ---------------------------------------------------------------------------
>>
>
---------------------------------------------------------------------------
Stephen M. Smith, Professor of Biomedical Engineering
Associate Director, Oxford University FMRIB Centre
FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK
+44 (0) 1865 222726 (fax 222717)
[log in to unmask] http://www.fmrib.ox.ac.uk/~steve
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