FRET - Image analysis - FRETR (Page 3)
The data text file will look like this. Note that in contrast to the spillover file, here the channel data is in groups of 6: YFP (545), YFP background (2nd 545), FRET (546), FRET background (2nd 546), CFP (480), and CFP background (2nd 480).
Note that the total intensity is the second to last value in each line.