AFNI Message Board

Dear AFNI users-

We are very pleased to announce that the new AFNI Message Board framework is up! Please join us at:

https://discuss.afni.nimh.nih.gov

Existing user accounts have been migrated, so returning users can login by requesting a password reset. New users can create accounts, as well, through a standard account creation process. Please note that these setup emails might initially go to spam folders (esp. for NIH users!), so please check those locations in the beginning.

The current Message Board discussion threads have been migrated to the new framework. The current Message Board will remain visible, but read-only, for a little while.

Sincerely, AFNI HQ

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Joel Welling
July 06, 2004 03:49PM
Hi folks;
We're having great success with 3DIntracranial, but occasionally we see a failure mode in which the probability distribution function fit produces very inappropriate results. For example,

Probability Density Function Estimates:
Background Coef = 0.692128
Background Mean = 27.026299
Background Std Dev = 422.610107
Gray Matter Coef = 0.351781
Gray Matter Mean = 30.472303
Gray Matter Std Dev = 12.040323
White Matter Coef = 0.124279
White Matter Mean = 61.410164
White Matter Std Dev = 12.066820

The background has been assigned a huge standard deviation, and I gather that is hiding the true means of the gray and white matter peaks. I know that we can explicitly set the min and max values used in the segmentation itself, but is it possible to set any of the PDF fitting estimates? I hate to override the whole PDF mechanism when it generally works so well.

Thanks,
-Joel
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Tweaking PDF fitting in 3dIntracranial

Joel Welling July 06, 2004 03:49PM