OK, my mistake, but still why min_stable and max_stable instead in between ( (70+140)/2 if I am getting right the initialization function)? And I'm writing it in the moment, I am a bit slow, sorry ;)
2009/3/8 Vasily Khoruzhick <[email protected]> > On Sunday 08 March 2009 11:50:22 Stefan Krastanov wrote: > > I believe I got it now. And yes - my first idea is senseless. But still I > > don't understand that correction - it's like if there is older correction > > done, you are changing the formula to (min_stable_yavg / current_yavg)^2 > = > > min_stable_exposure / current > > exposure. Why the square? And why are you aiming at min_stable_yavg or > > max_stable_yavg instead at the value exactly in between. > > It is not square, current_yavg is not constant. Here's quick example what > koef > means: > > 1. yavg = 10, min_yavg = 10, min_stable_yavg = 20, koef = 1, exposure = 5. > Algo will change exposure value to 10, to get yavg == 20 (We're trying to > get > values not on edges because we want to get yavg into stable region, not on > edge of stable region) > 2. Last time we performed exposure increasing, but yavg == 40 instead of > 20, > and max_yavg = 35, so we're out of region because we made too large step. > In > _this_ case algo will re-calculate koef. It's actually your "b" constant :) > > Btw, maybe there's error somewhere in calculations, I'll check later. > > > And I see one int i, that I think is not used anywhere, but that's not > > important. > > > > I propose to take exposure=a+b*yavg. The only difference is that "a" > there. > > But "a" will probably be near zero (zero luminosity - zero exposure) so > > maybe a better Idea is exposure=a+b*yavg+c*yavg^2. I will try both of > them > > but I would like to know what are those a,b,c calculated so if I use > > UDIA_INFO will I get few of them on dmesg (I'm just copying from the > switch > > few lines up.) or will I crash something. > > Talk is cheap. Show me the code (c) Linus Torvalds :) > Btw, don't forget about calibration - you should calculate your "a" and "b" > values dynamically, because yavg(exposure) dependency is different on > different sensors. > > With UDIA_INFO of course you'll get what you want printed on dmesg > > > Regards > > Stefan Krastanov > > Regards > Vasily > --~--~---------~--~----~------------~-------~--~----~ Lets make microdia webcams plug'n play, (currently plug'n pray) To post to this group, send email to [email protected] Visit us online https://groups.google.com/group/microdia -~----------~----~----~----~------~----~------~--~---
