How can I suppress the spuriously large % Change values from FIM+?
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Q49. How can I suppress the spuriously large % Change values from FIM+?
Voxels in the noise region have a very small baseline, and so can have a very large % Change value reported. This huge value can cause the true smaller % Change values to be lost in the quantization to 16 bits used in the final step of FIM+. To avoid this problem, set the Unix environment variable AFNI_FIM_PERCENT_LIMIT to something reasonable - 100, say. [08 Sep 1999: this setting also sets a limit on the value of the % From Ave sub-brick - see Q41.]
While I'm on the subject, the environment variable AFNI_FIM_BKTHR can be used to set the threshold for the suppression of the noise background in the FIM and FIM+ computations. For more details on these (and other) environment variables in AFNI, see file README.environment.
This FAQ applies to: Any version.
