HDR on or off during daytime driving?

Witch · Mar 27, 2024

Are you supposed to turn the HDR off during daytime driving? Leafless trees and the outlines of buildings look kind of weird with HDR on during daytime driving. I'm assuming it's because of the HDR on feature where it takes an overexposed/underexposed image to help with license plate reading.

The night time recording with the HDR is great. It's the daytime recording that looks kind of weird with HDR on.

Panzer Platform · Mar 27, 2024

Yes.
No.
It's complicated. lol

TonyM · Mar 28, 2024

Panzer Platform said:
Yes.
No.
It's complicated. lol

It's not easy if your camera doesn't switch HDR on and off at the appropriate times.

Panzer Platform · Mar 28, 2024

@Witch @TonyM

Ok, here’s the long version. lol
Generally yes, HDR is “only” for night time.
However, I’ve seen a few cases where HDR did better in daytime but the “majority” of the time HDR does worse in the daytime.
And of course every dash cam is different, so I was hoping OP would film his own test footage, review it with his own eyeballs, and do what’s best for his application.
And I’m sure this will change in the future as HDR gets refined, so I do not want him to trust me giving him an “absolute” answer.

Have a look at these two clips.
They were filmed simultaneously with two separate A229 Pro’s with identical settings.
Except one has HDR on, and the other has HDR off.
Take note of the HDR stamp in the text overlay at the bottom of the screen.
Can you spot the difference?

Dimitris1976 · Apr 19, 2024

I took those screenshots from your daytime YouTube videos in 4K.
That Chevy licence plate is definitely more readable with HDR turned off.

/Dimitrios

DigitalCorpus · Saturday at 10:07 PM

Yeah, so the HDR mode appears to be running the camera at 60 fps capture and then blending the frames together.
When you go from 30 fps to 60 fps, you halve the time between frames, (sorry for the pedantics here)
If you have a precise timer (light bulb goes off for a bug report I need to file) then you can essentially alternate some exposure information every frame
Run frame 0 at say ISO 50, shutter of 1/1000th of a second, aka 1 ms duration
Run frame 1 at say ISO 100, shutter of 1/4000th of a second, aka 0.25 ms duration, and apply a tone mapping curve
Blend frames 0 & 1 together with an average filter
Run frame 2 at frame 1's settings
Run frame 3 at frame 2's settings
Blend frames 2 & 3 together with an average filter

Now, it's not exactly this process as the second frame with the darker exposure will be be captured at nearly but not precisely immediately after the frame before it, there is a tiny delay seen at night, and this is not the only way to do an HDR exposure. Because of the blending that the Starvis 2 setup requires, you're essentially creating motion blur in the captured frame. This is how Sony does their HDR. It works great at night and we should have an EV based toggle, ideally, so we remove the motion blur at night.

Dadi_T · Sunday at 6:54 AM

When I have looked into the menu I was disappointed that N4 Pro didn't have an HDR timer, but when I had reviewed the footage I realized that there is no need to turn off HDR during day.
So, for N4 Pro, I really don't see any benefits of turning off HDR during day footage.
In fact, as you can see in the photo below, an license plate is visible with HDR on and totally unreadable with HDR off because of the sun.
Somehow, Vantrue managed to fine adjust HDR very good.

HDR Off