Olindo, I think the difference between a lin and a log measured channel (I can only speak for the facsstar+) is not only as easy. You have on the system a adjustment of the gain of the log amplifiers, which does NOT influence the lin channels I think. Therefore the relation between lin and log is more complicated, it looks like you have to add a constant k to the equation. Log values = k*10^(channel value/*scale factor) k has to be determined empirically and depends on the adjustment on the boards. With best regards from Munich Wolfgang Olindo Assis wrote: > > Dear Flowers, > > It was clear for me, after I read the answers to my question about mean > fluorescence channel analysis that most people suggested to analyze the data > using the original number "mean" from the Log scale (10^0 - 10^4). > > However, I had analyzed most of my data after conversion of original data to > channel values. Then, I start to have a problem because I did not want to go > back and reanalyze all data since we have over 2,000 files to be analyzed. > > Therefore I was looking for a formula (mathematical expression) to convert > the data back to Log values. Actually I found it on the CellQuest BD manual > on chapter 6 "histograms". They say that to convert channel values to Log > and vice-versa we just need to apply the following expression: > > Log values = 10^(channel value/*scale factor) > > where scale factor is 256 for a 0-1024 scale and 64 for a 0-256 scale. > > However, when I applied this formula to a group of data, that I had both > values (Log and channel values), I did not find this formula as the right > one to convert the data one to another. > > Does anyone have any experience with this. > > Best regards, > Olindo -- Dr. Wolfgang Beisker GSF - National Research Center of Environment and Health Flow Cytometry Group Ingolstaedter Landstrasse 1, D-85764 Neuherberg, Germany
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