ThresholdGridFloat thresholds a Grid< float >. The type 1 or type 2 threshold applied to the grid is the greater of the user-defined absthreshold, or the calculated threshold rt. The threshold rt is calculated based on the statistics of a windowed running average of the grid, using one of the following algorithms (relativealg): (0) [relative threshold not used] (1) rt = relthreshold * max(average grid) (2) rt = relthreshold * min(average grid) (3) rt = relthreshold * mean(average grid) (4) rt = max(average grid) + relthreshold * std(current grid) (5) rt = max(average grid) + relthreshold * std(average grid) (6) rt = min(average grid) + relthreshold * std(current grid) (7) rt = min(average grid) + relthreshold * std(average grid) (8) rt = mean(average grid) + relthreshold * std(current grid) (9) rt = mean(average grid) + relthreshold * std(average grid) If the user-defined absthreshold and rt are both zero (or if absthreshold is zero and the relative threshold is not used), the grid is passed through unchanged.

Parameters
None
Inputs
grid	Grid<float>	Input grid	Grid()
absthreshold	float	Absolute threshold	0.0
relthreshold	float	Relative threshold used to calculate the threshold rt according to the algorithm relativealg	0.0
thresholdtype	int	Threshold type: (1) values less than threshold set to zero; (2) threshold subtracted from all values, negative values set to zero	1
relativealg	int	Relative threshold algorithm: see system description. Set to zero if relative threshold is not desired.	0
nframes	int	Number of frames in windowed running average	1
Outputs
gridout	Grid<float>	Thresholded grid	Grid()
threshold	float	Threshold applied; the greater of absthreshold or calculated relative threshold rt	0.0
nover	int	Number of grid pixels above threshold	0
Subsystems
Last Saved: Thu May 29 20:57:46 MDT 2003 by TVE version 2007B