Conversion from Log to channel values

From: Olindo Assis (oamfilho@cpqrr.fiocruz.br)
Date: Mon Jun 05 2000 - 10:00:48 EST


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



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