Hello --
So, I'm learning a bit more about FPN. Here's my current issue -- FPN works great. Focus-pixel removal works great. But they seem to combine strangely?
I found this because I'm doing some custom video effect stuff that requires low-noise images because it does a lot of addition of frames, so if there is noise present it adds up and becomes visible. I noticed that a series of still raw images from the camera work fine, but I've been trying to use MLV video as an alternative route, and it doesn't work (yet!).
If I build a FPN profile and enable it, the noise drops significantly. But if Focus-pixel removal is also enabled, it also causes a bunch of red hot pixels to be created. I then enable the hot pixel removal, and that removes the hot pixels but it seems to add a bit of gray noise as well, as shown at the end of the gif below. (When I say "hot" here, I don't mean truly hot, just hot when I sum a lot of frames.)
Is this normal/expected, or is it some kind of error in the order of operations being done?
For example, it seems like the FPN also includes the focus pixels, so if I'm using both perhaps there is a math error when the FPN subtracts focus pixels that were already removed, which in turn causes the hot red pixels?
Here is an animated gif that shows the effect. I'm making the issue visible by turning up the gamma correction. Perhaps increasing the gamma is ruining the value of my experiment, but I do see the same scenario when I run them through my process (hot red pixels when I use FPN and use remove-focus-pixels but don't remove hot pixels), so I'm reasonably suspicious that it's related?
I suppose I could use MLVP to remove the focus pixels, and then do my own dark frame subtraction in processing (BTW -- it'd be great if there was a way to export the computed FPN frame -- if it didn't include the focus pixel removal also, that is.)
Thanks for looking at it! And let me know if I'm misunderstanding anything, or if a demo MLV would be useful.
