1) Shutters are not absolutely precise, so exposure difference in 2 stops then correcting to 2 stops will not result into absolutely same image (same pixel values)
2) There are slight light variations esp. in natural conditions (compared to halogen lamp powered by stabilized voltage)
3) There are light variations due to nature of light (photon noise)
4) FRV histogram/overexposure area calculations are not precise, but approximated to ~1/10EV
So don't expect that bracketed than exposure corrected shots will display absolutely the same overexposure area.
If you need precise (single value precision) overexposure calculation it is better to use RawDigger for that.
It is hard to discuss without
It is hard to discuss without having files.
In general:
1) Shutters are not absolutely precise, so exposure difference in 2 stops then correcting to 2 stops will not result into absolutely same image (same pixel values)
2) There are slight light variations esp. in natural conditions (compared to halogen lamp powered by stabilized voltage)
3) There are light variations due to nature of light (photon noise)
4) FRV histogram/overexposure area calculations are not precise, but approximated to ~1/10EV
So don't expect that bracketed than exposure corrected shots will display absolutely the same overexposure area.
If you need precise (single value precision) overexposure calculation it is better to use RawDigger for that.
--
Alex Tutubalin/FastRawViewer team