On Wed, 27 Apr 2016 15:53:55 +0100, NY wrote:

"Mr Macaw" wrote in message news
Go read up on it. People can detect flicker up to anywhere from 50 to
100Hz depending on their eyesight/brain speed. Pigeons are 120Hz, which
is why you shouldn't use ballast fluorescents in their dovecots.

I could tell the difference between a 50 Hz UK TV broadcast and a 60 Hz US
one, played on the same CRT TV. Especially if I saw the TV out of the corner
of my eye - apparently peripheral vision is particularly sensitive to
flicker and movement.

Likewise for 60 Hz non-interlaced computer screen versus 70, 75, 85 or 100
Hz; the latter all looked equally steady, so evidently for me the threshold
is between 60 and 70 for non-interlaced and between 50 and 60 for
interlaced.

I used to be a computer tech in the days of 60Hz monitors, and whenever I commented on someone's monitor flickering, about 1 in 5 would agree, and the others wouldn't know what I was talking about. The ones that agreed I bought them a 90Hz Iiyama and they loved it.

I think the blinking analogy might be a bit spurious. I think the brain is
*aware* of the momentary loss of picture but chooses to ignore it and to
fill in the gap.

I was always a bit sceptical of the claims of subliminal advertising
allowing unscrupulous advertisers to "plant" ideas such as "Buy XYZ brand
Cola" in unsuspecting customers' minds, because I could certainly detect a
single frame at 24/25 fps if it was different to all the others. I may not
know what was on that frame, but I'd immediately know "that was odd" and I'd
wind the tape/MPEG back for a second look or play it frame by frame if the
technology allowed, so it wouldn't exactly go unnoticed!

Agreed, I'd spot a frame too. It's called persistence of vision or something, similar to how they make dim LEDs appear brighter by pulsing them at brighter levels than they're capable of normally, so they don't overheat. The trouble is they seem to think we can't see the flicker.

--
They say Confucius does his crosswords with a pen.