Subscriber Discussion

The Cons Of WDR?

It doesn't seem to get mentioned much, but I've noticed one seeming con of WDR? It distorts the features of the face and other things, making them look matted. Maybe a review on how WDR can distort an image and why it may actually be a detriment in some situations?

From a manufacturer perspective, is there a way a camera can detect lighting levels so it knows when it needs to use WDR and when it does not?

Can you share an image as an example? Also, what WDR cameras are you seeing this on?

I'll try and dig up a sample image, but on a Sony camera with WDR I noticed peoples faces nearby seemed very "pasty", like they had heavy makeup on.

I think I kow what you are talking about. I've noticed something similar, though in such scenes usually a non WDR camera would be even worse with a very overexposed / dark face. Have you trietithe same scene with WDR on vs off?

We recently installed some Avigilon 3mp WDR domes. Excellent WDR during the day however the outdoor lighting created red scanning lines at night. Turns out there is a known issue with WDR and certain types of lights. The problem is fixed by turning the WDR off. Unfortunately we could not setup a WDR schedule so we stuck with the red scanning lines.

The great thing about Sony cameras is that you can turn off their Super DR at night so it doesn't cause issues. I found the same thing as the above poster, WDR looks great during day but the video is worse at night then before turning it on. If you can run scripts on your camera you may be able to turn it on/off if the feature is not built in.

I recently did testing on the WDR of a CH-140 Gen 5 Sony camera in an area with very strong backlight and shiny floors. I found the performance to be excellent although there was some slight distortion of the face when the person is moving. I also tested the same camera at night with exactly the same settings, it also performed very well.

Robert, thanks for posting an image! I agree there is some distortion. The key question is whether this is better or worse than what one would have gotten with WDR off.

John, it definately made a significant difference having WDR on. Sorry I don't have a comparison image available.

The difference was positive or negative. Meaning - was it better, all in all, to have WDR on or did it make it worse?

I should have said it made a dramatic improvement having WDR on.

That's generally what I have seen. While WDR does not deliver a perfect capture of a person's face, anytime you have significant sunlight, it's far better than what you would get with it off.

The distortions that we are talking about, even with WDR on, make automatic facial recognition difficult because it throws off the geometry of the face. However, that is a niche application and its better to get at least some view of the face than dark shadow.

Here is an image from the existing 4CIF Samsung WDR SVD-4120A camera for comparison. Note that this technology is several years old.

Given how overexposed the top center area is, it's hard to believe this is even WDR.

I checked the user manual for the camera and this configuration section makes me believe it's electronic / fake WDR:

In my experience, 'levels' are a sign of electronic, rather than multi-exposure WDR (see our tutorial on WDR implementations).