euler: Euler Character
In neuroconductor/ANTsR: ANTs in R: Quantification Tools for Biomedical Images

Description Usage Arguments Value Author(s) References See Also Examples

Mostly an for internal use in conjunction with resels. Calculates the euler characteristic at a threshold level.

1	euler(u, df, fieldType)

`u`	statistical value (typically the maxima of a cluster or statistical field)
`df`	degrees of freedom expressed as df = c(degrees of interest, degrees of error)
`fieldType`	T: T-field F: F-field X: Chi-square field' Z: Gaussian field

A vector of estimated euler characteristics for dimensions 0:D

Zachary P. Christensen

Worlsey K.J., (1996) A Unified Statistical Approach for Determining Significant Signals in Images of Cerebral Activation.

rftPval, resels

mask <- getMask(  antsImageRead( getANTsRData( 'r16' )  ) )
myresels <- resels(mask, c(1, 1))
# pretend these results are from a t-statistical field fitted with 10 df to
# find a peak value.
df <- c(1, 10) # made up degrees of freedom
ec <- euler(4, df, fieldType = "T") # peak value is 4
ez <- euler(3, df, fieldType = "T") # we thresholded at 3
# uncorrected peak-level p-value
pvox <- sum(ec * myresels)/sum(ez * myresels)