>Hello to All, > >There is a simple formula for converting log data to linear, and I have >forgotten. If anyone remembers this I would appreciate a quick note. >Thanks. > >Jim Phillips >University of Miami School of Medicine >Miami, Fla. Scale (linear) Value = f * 10^ [(C * n) / R] where C = channel number n = number of decades for the full range (~4 on BD & Cytomation machines, ~3 on many Coulters) R = range (maximum number of channels; typically 1024) f = log offset (typically 1 or 0.1) The FCS keyword $PxE (x = parameter number) has the values for f and n (e.g., <$P4E = 4,0.1> means that parameter 4 has a 4 decade range with the linear scale value of channel 0 equal to 0.1); $PxR has the value for R. Note that for most BD-generated FCS files, the offset for all log parameters is incorrectly stored in the FCS keyword list as 0 (zero); it should be 1.0. mr
This archive was generated by hypermail 2b29 : Wed Apr 03 2002 - 11:53:40 EST