Solving the Mystery of Horizontal Lines on Your Screen

• Quantumgravity
In summary: I believe this effect appears in "real life" too. It doesn't have to be on TV.Same effect can be demonstrated when watching a spinning wheel or a car tire. Our brain/eyes have some specific sampling frequency at which they "sample" the outside world. When the frequency of angular rotation is slightly higher then the sampling speed (angular speed < sampling speed < 2*angular speed) you're getting an effect which is called " folding" (sampled frequency is switched with a complex conjugate variant of itself + phase shift) and this effect causes you to see the wheel spin the other way. ;) Quite interesting actually, since it can be applied everywhere. Such as filming a computer screen or watching a movie etc..Thanks everyone
Quantumgravity
What causes the horizontal lines that move down a computer or TV screen when you video tape it?

You mean if you point a camera at a TV? The camera and TV do their thing in different ways - the camera takes full images 30 times a second, while the tv scans the frame one line at a time, 60 times a second. As a result, the camera sees the scanning of the tv.

oooh. I see. Thanks. And when we look at a TV or computer screen is it something with our eyes or the processing of info. in our brains that prevents us from noticing the lines? Or both?

Our eyes are too slow to see the TV image being refreshed, that's why you don't see the lines when watching TV.

This 'strobe' effect is also the reason for spoked wheels on TV sometimes appearing to rotate the wrong way.

Danger said:
This 'strobe' effect is also the reason for spoked wheels on TV sometimes appearing to rotate the wrong way.

I believe this effect appears in "real life" too. It doesn't have to be on TV.

Same effect can be demonstrated when watching a spinning wheel or a car tire. Our brain/eyes have some specific sampling frequency at which they "sample" the outside world. When the frequency of angular rotation is slightly higher then the sampling speed (angular speed < sampling speed < 2*angular speed) you're getting an effect which is called " folding" (sampled frequency is switched with a complex conjugate variant of itself + phase shift) and this effect causes you to see the wheel spin the other way. ;) Quite interesting actually, since it can be applied everywhere. Such as filming a computer screen or watching a movie etc..

Thanks everyone.

I don't think that the so-called strobe effect happens in the 'REAL' real world. What I mean by this is that it is not noticed in good old plain and pure sunlight. It is noticed under artificial lighting due to the 50/60 hertz that our eyes cannot see normally.

1. What causes horizontal lines to appear on my screen?

The most common cause of horizontal lines on a screen is a loose or damaged cable connecting the monitor to the computer. Other possible causes include a faulty graphics card, outdated display drivers, or a malfunctioning monitor.

2. How do I fix horizontal lines on my screen?

The first step is to check the cable connecting your monitor and computer to ensure it is securely plugged in. If that does not resolve the issue, try updating your display drivers or resetting your monitor's settings to factory defaults.

3. Why do horizontal lines only appear on certain parts of my screen?

This could be a sign of a damaged or failing graphics card. It is recommended to run a diagnostic test on your graphics card to determine if it needs to be replaced.

4. Can horizontal lines on my screen be a sign of a virus?

In rare cases, horizontal lines on a screen can be caused by a virus or malware. It is important to run a virus scan on your computer to rule out this possibility.

5. How can I prevent horizontal lines from appearing on my screen in the future?

The best way to prevent horizontal lines on your screen is to regularly update your display drivers and keep your computer and monitor in a well-ventilated and dust-free environment. Additionally, try not to move or bump your monitor too often, as this can cause loose connections and potentially lead to horizontal lines.

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