Hikvision ColorVu white line blinking problem

[baghirli]

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The other 2 colorvu cameras did not have this problem. We checked the connection, there are no problems. The energy is enough. But they are fed from a PSU. 12V 5A. I heard that connecting a separate 1A PSU to each solves the problem. What do you think?

 

[alastairstevenson]

I heard that connecting a separate 1A PSU to each solves the problem.

No, it won't, because the power supply to the camera is not the cause.

The human eye does not see that the lights from the window are pulsing in brightness at the frequency of the mains supply, the light is not completely steady.
This can cause the camera to catch successive images of the light when the light is at slightly different brightness levels, depending on the fps (frames per second) that the camera is set to use, causing the pulsing effect.

It's called a 'beating' or 'stroboscopic' effect where the pulsing frequency is based on the difference between the camera frame rate and the mains frequency.
It can be caused by a wrong selection of the frequency (50Hz Europe / 60Hz USA) in the 'Video Adjustment' setting of Image | Display settings in the camera web GUI.
You will be able to demonstrate it by changing the camera FPS setting and observing the effect.

 

[wittaj]

Yep typical behavior that folks are seeing more frequently with all the LED lights PLUS people realizing that in order to get clean images of perps, the shutter speeds need to be faster.

I think @alastairstevenson meant shutter speed instead of FPS. You slow the shutter down enough and the blinking goes away, but then motion will be a blur.

Here was a recent thread demonstrating this.

Weird things with Christmas lights

So see the lighted Christmas ornament on the deck? (gold wireframe package with balls in it) See how the lights dim and brighten on a set interval? Yeah, so in real life they dont dim and there is no dimmer control... Two separate 5442's seeing same

ipcamtalk.com

 

[alastairstevenson]

I think @alastairstevenson meant shutter speed instead of FPS.

No, I did mean FPS, ie the rate at which frames are grabbed, not the duration used to capture a frame.
It's the different frame rates between the camera and the lights that provides the beat frequency.
If they are the exact same frequency, there is a static banding effect across or down the image, the number of bands depending on what multiple of the camera FPS the mains frequency is.

You slow the shutter down enough and the blinking goes away, but then motion will be a blur.

Yes, agreed, because when the image is captured over a longer time, the brightness of the LED has moved over more of the mains cycle, and evened out part of the brightness change over the cycle.

I'd guess that checking the 'Video adjustment' setting (50Hz or 60Hz) might make an improvement.

 

[wittaj]

Interesting - I can make the FPS whatever I want and still get the LED flicker and it is changing shutter speed that stopped it.

Why then if you use anti-flicker in Dahua cams it limits the shutter speed you can use and not FPS?

 

[alastairstevenson]

Why then if you use anti-flicker in Dahua cams it limits the shutter speed you can use and not FPS?

The slow shutter speed averages out the brightness cycle of the LED.

You will be able to demonstrate it by changing the camera FPS setting and observing the effect.

This was as much about demonstrating the cause of the flicker (ie not due to the power supply) and seeing the change in the strobe frequency.

 

[trempa92]

I agree with @wittaj , fps is only "output" of what shutter actually capture. And never really fixed pulsing problem for me. But shutter speed does.

 

[baghirli]

Yep typical behavior that folks are seeing more frequently with all the LED lights PLUS people realizing that in order to get clean images of perps, the shutter speeds need to be faster.

I think @alastairstevenson meant shutter speed instead of FPS. You slow the shutter down enough and the blinking goes away, but then motion will be a blur.

Here was a recent thread demonstrating this.

Weird things with Christmas lights

So see the lighted Christmas ornament on the deck? (gold wireframe package with balls in it) See how the lights dim and brighten on a set interval? Yeah, so in real life they dont dim and there is no dimmer control... Two separate 5442's seeing same

ipcamtalk.com

Unfortunately, it was an analog camera. There is no shutter speed setting. I looked at the OSI menu. Only the slow shutter setting came out. I changed it. There was no change. I changed the FPS. Failed again. From 15 fps to 12, 10, 8, 5. I checked them all. Unfortunately it didn't work. If it is caused by lighting, then the lamp is a standard tungsten lamp. Because the flickering effect occurs in tungsten lamps. But because the LEDs work with DC voltage, they do not blink. It means that it will be fixed if the lighting is changed. And I should note that there was no tungsten light in the view of other problem-free cameras. But I think the Energy factor may have a role. There are many reasons.