Why Do Screens Look Wavy in Photos?

A screen that looks quite normal when you look at it with the naked eye, for some reason in the photo. in rainbow colors and a wavy pattern visible.

This situation appears a little differently on some screens. Especially on CRT (known as tube) monitors “a thick horizontal bar” it starts to flow vertically quickly (as in Mor ve Ötesi’s music video I Have a Problem).

You are no stranger to this image. A computer screen that looks different in reality and on camera:

Before explaining the reason for this, we need to explain the working logic of the screens of digital devices. In fact, your laptop, monitor, TV or phone The screen is constantly changing.

All these devices have different speeds. “refresh rate” has. The refresh rate is how often the image on the device’s screen changes per second. This speed differs between screens. The following refresh rates are generally used today:

• TVs: 75Hz-120Hz
• Computer monitors: 60Hz-360Hz
• Phones: 50Hz-120Hz

You think you’re seeing a moving image on the screen, but the image itself isn’t actually moving.

appearing incredibly fast on the screen, then your brain corrected, multiple frames pass on the screen suggesting that something is actually moving. The higher the frame rate per second, the more believable the motion will appear on screen.

Now that you know how computer and TV screens work, let’s take a look at how cameras work.

Here “shutter speed” You need to know how it works. Shutter speed is the amount of time the shutter stays open during an exposure. It means how much time your camera took to take that photo. The longer it takes, the blurrier the photo will be (if you’re trying to take a photo of a moving object).

Most modern DSLR and mirrorless cameras have a very fast shutter speed, ranging from 1/4000 to 1/8000. This, that the camera captures the image means it takes 1/8000th of a second.

Now let’s come to the place where the zurna calls zırt:

As we mentioned earlier, the image on your TV/computer screen is constantly changing between 50Hz and 360Hz. We also talked about how the shutter speed on cameras works. Now when we put this information together A light bulb will go on in your brain.

A camera with a slow shutter speed it will capture the screen in the middle of the refresh process. The higher the refresh rate of a screen, the smoother the image.

Let’s take a look at the OLED screens on phones:

On some displays of this type, the brightness is adjusted using the pulse width modulation (PWM) method. screen backlight, continuously on and off at high speed(as we mentioned in the example above).

For example, if the screen brightness is 40%, the backlight works with a 40% duty cycle. This is the screen every cycle. Renewed with 40% bright section and 60% dark section It means. Because the camera – unlike our brain – can detect these dark parts, ripples or lines appear in the viewfinder or in photographs.

If the screen brightness is 100% Since the bright sections will also be 100% this problem does not occur. So before taking a picture of the phone’s OLED screen, set the screen to maximum brightness.

We also need to mention another phenomenon that causes this situation:

Screens are a grid of pixels. A digital photograph is also a grid of pixels. These When they overlap, a moiré pattern is formed.

Some of these pixels overlap, while others do not. Therefore, waves and stripes are formed. Just as in the screenshot below as are:

Same effect, two pieces standing in a row on the window curtain You can also see. Even some garments, such as sweaters, may appear wavy in videos for the same reason.

So why don’t we see this problem on screens in movies?

Movies at 24fps withdrawn; that is, while watching a movie, you will see 24 still images (frames) projected onto the screen in one second. Action movies and video games have higher frame rates to make the action look even smoother.

The refresh rate of the screen and the shutter speed of the shooting camera by syncing Films avoid this problem. In the same way, you can take better photos and videos by providing this equality. You can adjust these speeds in the settings section of your computer or phone/camera. You can also try adjusting the brightness, contrast and distance.

Sources: Camera Gurus, Science ABC, WIRED, Consumer Huawei