Hi,
while looking and the SainT changelog I've noticed that it has been using gamma correction for some time and there is even a note about other emulators lacking this feature as well. So I did a couple of screen grabs, while I'm at Lotus frenzy ;)
Hatari:
SainT (without SC 1224 emulation but with gamma correction):
SainT (with SC 1224 emulation and with gamma correction):
Falcon/RGB photo:
Falcon/VGA photo (same monitor as used for the emulator grabs, btw):
So it seems to be true -- Hatari screenshot is definitely darker than the others. I must admit, the SC 1224 emulation in SainT is quite cute, along with the floppy sound, it makes me feel very oldschool. :)