Purple picture

[GT60]

Hi
Why is my front camera is showing a purple haze picture yet my rear camera is okay.
It has been like this for a few days now and unsure what to do as i have not altered anything
The NVR and IP cameras are Dahua and the system is about 5 - 6 years old.
Thanks

 

[bigredfish]

I'm guessing stuck physical IR cut filter.

Cycle the power to the camera a couple of times, or give it a good slap

 

[GT60]

EDIT I have just turned the NVR off and restarted after a few minutes and now back to normal for some reason.
What's a Physical IR cut filter?

Thanks

 

[bigredfish]

Many cameras have a physical filter that moves in front of the lens to facilitate IR. Sometimes this gets stuck. You can often hear a clicking noise when it moves in/out of the way of the lens

 

[TonyR]

Just to add to what @bigredfish said:

The mechanical IR-cut filter is supposed to open at night time allow IR produced by the camera's IR LED's to be reflected from images and into the image sensor for nighttime operation. In the daytime the IR-cut is lowered in front of the sensor to keep IR out. If the IR filter fails to operate properly in the daytime the IR component of normal daylight will cause a purplish hue.

You can hear the click when you cover the lens with your hand during the day because a light sensor "thinks" it's night time so it turns on the camera's IR LED's and opens up the IR-cut filter so the camera can "see" the IR from it's LED's reflected off objects and into its image sensor. When you remove your hand from the lens the light sensor behind the lens sees daylight, turns the LED's off and the filter is lowered to keep natural IR out of the sensor.