Low light video preference - Quality vs Detail

[TonyM]

What is more important to you in a dashcam recording in low light - image quality or detail? Ideally we would have both, but the limitations of the sensors and lenses used in our dash cameras means there is usually a compromise. Turning up the gain increases the noise and loses fine detail, however the exposure time is reduced and therefore motion blur is also reduced. The high noise video is not really one to keep and share with friends & family, but the better-looking low noise video might not record essential details.

Take these two examples. Both cameras are set at 30fps.
A119 1440p30 - low noise - motion blur
Mobius 2 1080p30 - high noise - less motion blur





If you needed to submit video evidence in the event of an accident, which one would you prefer to have available? Of course that may depend on the nature of the incident. A number plate of the car in front may be more important than the plate on an adjacent vehicle or a stationary object at the side of the road, for example.

 

[SawMaster]

Presuming there's enough light with both, I prefer seeing details because those are what is used to identify one thing from another similar thing

Of my economy cams I have IMX323 and AR0330 sensors with the former better at night and the latter better daytime. But the 0330 sees so little at night that even with worse image quality the 323 beats it hands-down because at least you see something instead of nothing Until we get one sensor that does both day and night at a top-level, you really need 2 cams to always get the best

Phil

 

[estore009]

I prefer seeing details +1

 

[TonyM]

Until we get one sensor that does both day and night at a top-level, you really need 2 cams to always get the best

Phil

So day & night cameras, in addition to or in combination with wide angle and telephoto views?

 

[TonyM]

Presuming there's enough light with both, I prefer seeing details because those are what is used to identify one thing from another similar thing

Phil

What about the difference between fine detail captured with low noise (such as when stationary) and coarse detail on moving objects which is often lost to motion blur? If you are in an accident, that will usually involve relative movement between your car and another object (car, cyclist, tree etc.).

I'm starting to think that I will accept higher noise in return for shorter exposures and less motion blur, at least in low light where it seems to make a difference. Whilst testing the Mobius 2 I have noticed that it consistently uses shorter exposures than all my other cameras, even when they are all set at 30fps. It certainly makes for a good second camera, if not necessarily a good primary camera on its own.

 

[SawMaster]

I'm starting to think that I will accept higher noise in return for shorter exposures and less motion blur, at least in low light where it seems to make a difference.

Day or night, parked or moving, what I want to capture are sharp details such as plate numbers or faces. If the rest is also good that's nice but IMHO not as important in a dashcam I'm not making a Hollywood movie- I'm collecting evidence. Even a blurry or discolored image will show an object's position fairly well and my own lane position will be clear. Those points are what will matter most after an incident.

Of course I'd like to have everything always looking perfect but in devices this small and cheap I don't see that as possible for many years to come. And even then I probably couldn't afford cams like that

Phil

 

[Deleted member 46308]

Day or night, parked or moving, what I want to capture are sharp details such as plate numbers or faces. If the rest is also good that's nice but IMHO not as important in a dashcam I'm not making a Hollywood movie- I'm collecting evidence. Even a blurry or discolored image will show an object's position fairly well and my own lane position will be clear. Those points are what will matter most after an incident.

Of course I'd like to have everything always looking perfect but in devices this small and cheap I don't see that as possible for many years to come. And even then I probably couldn't afford cams like that

Phil

Agree

 

[Nigel]

Take these two examples. Both cameras are set at 30fps.
A119 1440p30 - low noise - motion blur
Mobius 2 1080p30 - high noise - less motion blur
View attachment 34322
View attachment 34323

Interesting that in your second set of images the car plate is more readable on the low noise A119, and there is a lot more detail of the dirt on the window. The lorry plate however is far too blurred by the A119 to be readable.

Clearly there is a compromise to be made, somewhere in the middle, depending on the relative speed of the vehicles - if you are going a similar speed as with the car above then you want low noise, if you are going significantly faster as with the lorry then you want faster exposures, if you are going in opposite directions then you need a faster sensor such as the IMX291!

In general noisy images are bad because they compress poorly and detail is lost, but I would choose less motion blur in your example.

 

[TonyM]

Day or night, parked or moving, what I want to capture are sharp details such as plate numbers or faces. If the rest is also good that's nice but IMHO not as important in a dashcam I'm not making a Hollywood movie- I'm collecting evidence. Even a blurry or discolored image will show an object's position fairly well and my own lane position will be clear. Those points are what will matter most after an incident.

Of course I'd like to have everything always looking perfect but in devices this small and cheap I don't see that as possible for many years to come. And even then I probably couldn't afford cams like that

Phil

You're right that even a blurry or discoloured video will show which lane you are in, and who moved towards who etc. Even a cheap 720p camera can do that, so long as it is sensitive enough to gather some light at night.

 

[TonyM]

Interesting that in your second set of images the car plate is more readable on the low noise A119, and there is a lot more detail of the dirt on the window. The lorry plate however is far too blurred by the A119 to be readable.

In general noisy images are bad because they compress poorly and detail is lost, but I would choose less motion blur in your example.

You make a good point about noisy video being harder to compress.

The car is generally sharp in the second A119 image because it was not moving across the frame - we were travelling in the same direction at about the same speed.

The speed differential to the lorry was barely 10mph, so it doesn't take much to blur away details. However I acknowledge that as far as evidence is concerned, the main thing is that the video would show whether or not the lorry moved into my lane, for example. If needed, the A119 video from a few seconds earlier did show the number plate.

 

[kamkar]

Detail is what i like.
So what we need are cameras that are able to use a faster exposure,,,,, without ramping ISO to noise-generating levels like the M2 appear to me to be doing.
There are noise suppressing tech out there, but its not something i would rely on other then maybe cosmetic cleanup of a already good image.

 

[TonyM]

Detail is what i like.
So what we need are cameras that are able to use a faster exposure,,,,, without ramping ISO to noise-generating levels like the M2 appear to me to be doing.
There are noise suppressing tech out there, but its not something i would rely on other then maybe cosmetic cleanup of a already good image.

Noise reduction has a tendency to soften an image and reduce detail. Certainly it will not add any detail that is not already there. However if it is done right it can make the finished video more pleasant to watch.

 

[Rajagra]

In a dash cam, detail IS the quality!

 

[Masejoer]

What about the difference between fine detail captured with low noise (such as when stationary) and coarse detail on moving objects which is often lost to motion blur? If you are in an accident, that will usually involve relative movement between your car and another object (car, cyclist, tree etc.).

I'm starting to think that I will accept higher noise in return for shorter exposures and less motion blur, at least in low light where it seems to make a difference. Whilst testing the Mobius 2 I have noticed that it consistently uses shorter exposures than all my other cameras, even when they are all set at 30fps. It certainly makes for a good second camera, if not necessarily a good primary camera on its own.

Set exposure compensation?

 

[c4rc4m]

The noise is most likely the result of "Gain" which is the electronic amplification of the weak sensor signal by the camera, it's common to all video cameras.

What appears to be happening is the Mobius has chosen a faster shutter speed which preserves the detail better but results in less light hitting the sensor, and so requires more gain to produce a bright enough picture.

The real answer here would be a more sensitive sensor, so the faster shutter speed could be used without the need to increase in the gain. However, there may be cost / practicality considerations, although ultimately this is what I'd like to see make it's way into more dashcams, eg Sony Starlight series sensors.

Personally, as video, I prefer the top capture, but if needing it for evidential purposes would take the bottom one every time.

 

[Rajagra]

Worth noting that the Mobius image is brighter AND using a faster shutter speed, so it is not surprising there is grain. In the first two shots the number plate is better from the Mobius, because motion blur has affected the A119. But in the second pair the car is moving more directly forwards and its number plate is hit by the cammer's headlights, so the A119 has done better. (The reg does end in H, not M - I looked up the plates.)