*** WARNING: Identical ID codes

AFNI version info (afni -ver):
Hi all,

I am using AFNI_21.2.04 'Nerva' for visualization. I processed 600 DWI through FSL and am using AFNI for visualization of the resulting FA maps. When I open AFNI in a directory containing all 600 FA images I get the following warning for a few of the files: "*** WARNING: Identical ID codes in".

What does this warning mean? I've checked a few of the files that the Warning popped up for and they are indeed different. Should I be concerned about this?

Thank you in advance,

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Hi all,

Just checking in on this to see if any of the AFNI team have advice.


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On 09/25/2012 08:16AM by Daniel Glen wrote:
"You probably used cp to copy the dataset to a new file name rather than 3dcopy. Use 3dnewid to generate a new id code too."

in response to the same query.

Hi Matthew,

Thanks for the response. I had seen this previous post but my images were not copied. I split a concatenated dataset of 640 independent images using FSL. When running afni in this directory for visualization I get the ***WARNING:Identical ID codes for images 100 IDs apart:

*** WARNING: Identical ID codes in /data/vol0027.nii.gz and /data/vol0127.nii.gz
*** WARNING: Identical ID codes in /data/vol0042.nii.gz and /data/vol0142.nii.gz
*** WARNING: Identical ID codes in /data/vol0050.nii.gz and /data/vol0250.nii.gz
*** WARNING: Identical ID codes in /data/vol0107.nii.gz and /data/vol0207.nii.gz

I've compared the images that have the same ID codes in the AFNI viewer and at the voxel level they have different values. Moreover, I've compared the original unprocessed version of these images and they do not appear to be the same.

Is it possible that AFNI misassigned the ID codes or does this always indicate a copy?

These diffusion datasets were fully processed in FSL. I was just using AFNI for visualization when I came across this error. Please let me know if you have any advice about this case.


That is strange. These should be generated on the fly for each then. Do you find these datasets have duplicate IDs when you use this command on each of the matching pairs?

3dinfo -id mydset.nii.gz

Instead of the on-the-fly ID creation, you can add an AFNI extension to the NIFTI that will include a new ID with this command:

3drefit -newid mydset.nii.gz

You might try updating your version of AFNI too. It's a couple years old although I'm not aware of any changes related to this. Thanks for letting us know about this.

We have seen this before. The method to generate ID codes is not as random as we might have hoped. For example, using 3dTsplit4D to break up a time series will pretty reliably show this problem. It has been on the todo list for many years, unfortunately...

  • rick

Thank you Daniel and Rick for the information!

Daniel - when I ran 3dinfo -id on pairs of images from the warning messages they indeed had the same ID codes. I ran 3drefit -newid on these images and they assigned new codes to the images. So the warning no longer comes up.

Originally, I was worried that the identical IDs indicated that I had repeat datasets in my analysis. However, it seems that the ID generation is meant to be completely random and not meant to catch repeats. This answers my question.

Hi Jenna,

Okay, we finally looked into this more deeply and noticed that a new ID should be assigned upon any name change, which was not being done. This should fix the problem for creation of new datasets (or reading some without id codes, such as NIFTI), it will not do anything about old ones though.

If you would like updated binaries for this, please let me know. If you compile yourself with build_afni.py, go ahead and run the build anytime.

Thanks a lot for bringing this up,

  • rick