What causes images to flicker when scrolling?

Question

I have no idea what causes this, so I'll refine tags as some answers/comments start to guide me in the right direction.

Sometimes, images with monochrome stripey parts (whether the whole image is colour or not), exhibit a strange flashy effect as I scroll past them.

This is where I most recently saw it, in an article on Dezeen:

As I scroll past that image (with Chrome on OS X 10.9) the wall on the right goes darker and brighter, according to my rate of scroll.

If I get just the right scroll speed, it doesn't flicker - but it is in the 'dark mode', like someone in the scene has turned the lights off. If I speed up or slow down, it begins to flicker again - so I'm pretty sure it's not an optical elusion!

I saw it before with a couple of .gifs, I thought maybe it was a strange property of them. But the image above a is a .jpg.

What causes this effect?

Answer 1

I just tried to scroll this image down with my screen refresh rate at 60 Hz then 75 Hz: it seems to flicker more at 60 Hz... Maybe it's also due to display lag.

PS: You may have more precise answers here: http://physics.stackexchange.com

Answer 2

I think this is a Moiré optical illusion due to the wall's thin, closely put together horizontal lines, not anything to do with scrolling or display at all.

@SkipR's reply should have been the accepted answer.