## S3 method for class 'dtiData':
sdpar(object,level=NULL,sdmethod="sd",interactive=TRUE)dtiDatalevel. As a default the value in object@level is used. The value determines the lower endpoint of the linear section in the model for error standard deviation as a function of the mean."sd" or "mad".TRUE a density of values in zero weighted images is plotted together with
the specification of the lower endpoint of the interval of linearity. A good choice of this point should correspond, if present, to the minimum between the first twdtiData.dtiData,
readDWIdata,
dti.smooth,
dtiTensor ,