HDR - False & Misleading Advertising

[Chuck McCoy]

“Ask a question you’re fool for a minute, don’t ask you’re a fool for life”
-John Wayne
I got a question via email from a viewer that watched my A119 Mini 2 YouTube review.
He wants to buy his first dash cam.
He started looking at the different @viofo models on Amazon, and is confused by the term HDR.

These are his questions;
1.) Is HDR a real thing, or just marketing BS?
2.) What is the difference between these HDR’s, (see attached screenshots)?
(A119 V3) “True” HDR
(A119 V3) “Multiple Exposure” HDR
(A119 Mini) “HDR Super Night Sensibility”
(A119 Mini 2) “DOL-HDR”
(A139 Pro) “HDR NIght Vison 2.0”
I started typing a response to answer his question because I thought I knew what HDR was.
After looking into it further I’m not qualified to answer his question.

How can I explain this in one sentence so even a ten year old child could understand?
-Chuck

 

[kamkar]

Yeah it is a bit of a mess having to explain, and the brands are not helping using a slew of different names for it.
The new starvis 2 sensors support the Sony clear HDR, which as i understand it is 2 frames with different parameters shot at the same time, and from Sonys own stuff on it just make you go " OMG this is just what ve need in dashcams"
CUZ compared to DOL HDR that is also just fine but 2 consecutive frames stitched together digitally, then you get this smeared result at least with fast movement in the frame

We have also seen the issues with WDR, where at least for a while in most systems it wasent really recommended to have on.

I still think HDR is a part of dashcam future, but i also right now feel a little that the code for it are not really cracked yet.
Needless to say the newer sensors and their improvements in the basic features of the image sensors are also a must have, but i think we will all be wise to not just throw our arms in the air and think all our woes are over.

I like to play around with poor mans HDR in the form of bracketed photography, so i often use it taking 5 pictures in a row each with a little different settings ( EV value ) so you get a string of photos with EV -1 / -0.5 / 0.0 / +0.5 / +1.0
You can then import those into a software like lightroom or others that can handle such things, and then you can take the most interesting parts of each frame and paint them all together to one super frame.
This could for instance be take the brighter shadow parts from the exposure that highlight those, and then use the underexposed frames in relation to the sky to have that be more relaxed

In daylight you can easy snap such photos with a handheld camera as the 5 photos are snapped in a split second, this can also account for some movement in the frame, but some softwares can even account for this and auto allign the framed to compensate for that.
If you are taking really low light, well then you really do not want movement at all, so even leaves on a tree in frame, if they move a little due to wind, well they will turn into a blur due to the average slow exposure time.

This 2 pictures are the extremes of a 5 shot bracket, as you can see at least in regard to the setting sun you will like to use that part of this frame, but other parts of it are pretty dark so for those you will need to use info from one of the other 4 photos.

And then the overexposed one from the other side of the 5 picture stack, here you might only want to pick shadows as they are better exposed here, but the rest of the picture too much exposure.

Finally a end result picture taken in hand using my small action camera.
But it is 5 pistures i have mixed together to one.

 

[Dashmellow]

How do I explain this to someone who has no experience with dash cams, and is most likely not tech savvy at all?

I would explain HDR to your inquiring viewer who has no experience with dash cams, and is most likely not tech savvy at all as follows:



Dynamic range is the ratio between the largest and smallest values that a certain quantity can assume. It is often used in the context of signals, such as sound and light. In photography, dynamic range describes the ratio between the maximum and minimum measurable light intensities of black and white, (dark shadows and the brightest areas in an image).

For certain technical reasons it is difficult to easily capture both the darkest and brightest areas in a photographic image at the same time. This is referred to as “limited dynamic range”. Shadow areas might look completely black with no details and very bright areas will be blown out and also have no detail, instead just looking pure white or yellow.

HDR is a term that means “High Dynamic Range". It is a technology that seeks to expand the otherwise limited dynamic range to enhance the capture of details of both the darkest shadow areas and most brightly illuminated areas of an image at the same time.

For dash cams the most common current approach to HDR is “Multiple Exposure” HDR. This technique shoots two simultaneous image frames at 30 fps with one image exposed and optimized to capture the shadows while the other image is optimized to capture the brightest areas of the scene. It then combines and blends the frames into a single image with both the darkest and lightest areas properly exposed.

The technology continues to improve and so now we are beginning to see “DOL-HDR” which is related to what is described above and it stands for “Digital Overlapped HDR. It uses a line by line mixture of exposures instead of the frame by frame exposures of "Multiple Exposure” HDR.

The technology is not perfect and doesn’t always prove 100% effective but HDR is a real thing and is not “marketing BS”.

HDR when matched with certain CMOS sensors has shown the ability to freeze and capture certain license plates at night from fast moving vehicle coming towards you due to how the technology works. This is another benefit of this technology but not really one that has anything to do with dynamic range even though the multiple exposures make this work.

The latest CMOS technology from Sony, the Starvis 2 sensor is inherently better at capturing a wide dynamic range of dark and light in the same image than previous generations. When combined with Digital Overlapped HDR, “DOL-HDR” plus signal processing and noise reduction it performs extremely well, especially in low light. I believe this is what is being referred to as “Super Night Vision”. So, the capability to work well in low light is a real thing but the terminology seems to be more of a marketing term.

 

[Raaz]

Yeah HDR in cameras always means "Higher dynamic range compressed into lower dynamic range by mixing multiple frames somehow and hopefully without losing too much detail".
In opposition to HDR in TVs, where it means "This display can go super bright and super dark within the same still image", basically not needing the range compression the cameras do.
And the third part is that most camera sensors and video formats don't have enough brightness-steps to capture nature's dynamic range.

While you need HDR source material for these TVs to display actual HDR, camera HDR is there to see all information from HDR on NON-HDR displays. Plus sensor limits.

Basically capturing a true HDR TV and make it visible without losing information on a non-HDR TV.

I thought this might be a different, hopefully interesting perspective on HDR, since we get bombarded with the same term for TVs and cameras, while they mean something different.

To actually find out what each camera does is impossible. One can only compare footage and then judge by that. It's their "secret magic with fancy names".

And a little example in numbers:
Imagine a fantasy brightness scale going from 0-100.
Direct sunlight + dark tunnel = 0-100 (or driving at night with bright lights onto the reflecting license plate)
Human eye = 5-80
HDR OLED TV = 0-50
HDR standard TV = 15-70
Great camera sensor = 5-90 ; max range in 1 frame = 60
Bad camera sensor = 20-80 ; max range in 1 frame = 35

Camera HDR = 2x 30 fps, somehow mixing 2 frames from their sensor range into one frame with a compressed range of 20-60.

 

[Dashmellow]

As you mention in your post, HDR in a capture device like a camera is a completely different thing (and technology) than HDR is in a display device like a TV.

Although the goal of each technology is the same (capturing and displaying the fullest range of discernible tones between black and white) they are completely different things that use the same HDR term.

A TV with the latest HDR technology cannot display a full tonal range image unless the image it is trying to display already has the full range of tones captured by the camera. On the other hand an improperly configured HDR TV can display a perfectly exposed image very poorly.

And a little example in numbers:
Imagine a fantasy brightness scale going from 0-100.
Direct sunlight + dark tunnel = 0-100 (or driving at night with bright lights onto the reflecting license plate

Here's a visual example of the brightness scale you are talking about comparing the dynamic range of the human eye to a typical DSLR.
The HDR function on a TV can expand and contract the display of the number of tones one can see, but they have to be there in the original image for it to do that, although with digital processing it can fake it to some degree. (and eliminate banding)


This graduated grayscale chart isn't all that accurate. It is really just an illustration of the concept of dynamic range.

 

[viofo]

Before the HDR came out, most dashcam companies advertised the WDR, we thought WDR is almost useless.

(A119 V3) “True” HDR ----Almost the first dashcam implemented the HDR on IMX335, we call it TRUE HDR means it really helps to improve the video quality, like some times we call the 4K camera REAL 4K, as there are too many fake 4K cameras on the market.
(A119 V3) “Multiple Exposure” HDR -----This is how the HDR works, more technically.
(A119 Mini) “HDR Super Night Sensibility”-----The main chipset updated, and the HDR is perform a little better than on V3.
(A119 Mini 2) “DOL-HDR” --- This is what Sony called on their sensor spec, users can find more related info on the internet.
(A139 Pro) “HDR Night Vision 2.0” -- With the IMX678 sensor, it seems to bring HDR to the next level.

All over HDR tech is the DOL-HDR.

Sony explained in detail about the DOL-HDR and CLEAR HDR on their official website.

We thought there is some disadvantage of clear HDR for night recording, maybe not suitable for dashcams.

In the future, maybe there is 3 frames HDR tech, expect to see how it performs.

 

[Dashmellow]

we thought WDR is almost useless.

Couldn't agree more!

Thanks for the more detailed explanations of the different HDR implementations.

 

[Chuck McCoy]

we thought WDR is almost useless.

Since 2020 I've tried WDR on Viofo dash cams, and I have never observed an improvement in image quality.
I wish WDR is discontinued in all future Viofo dash cams, and maybe even removed from all past Viofo dash cams.
Here's a clip from March 11, 2020 with the A129 Pro;

 

[Dashmellow]

Actually, somewhere on DCT I once demonstrated WDR both on and off (using a Street Guardian SG9665GC) driving through the same high contrast conditions a few minutes apart. (I doubled back and drove through the same section of road at sunset through trees again after changing the setting), Yes, the WDR actually functioned but the effect was really quite minimal. Basically, it opened up the shadow details in the trees and shrubs along the roadside slightly but had virtually no effect on the blown out highlights on the pavement in bright sunlight.

If I have a camera with WDR only I will probably deploy it (like the Mobius where it actually seems to do something useful) but I don't expect much from it.

 

[BlackboxMyCar]

Wow! Some amazing in-depth insight in this thread. HDR is definitely a large part of image quality for us, and I feel like this can even be evident in the U3000's lack of HDR, compared to the A119 Mini 2's inclusion of HDR, and how the night vision can differ, despite both units using all-new image sensors.

Don't want to overshadow the expert voices here, but as Panzer Platform was looking for a very basic understanding of what HDR is, we have a short snippet covering the basics of what HDR is here.

 

[Nigel]

These are his questions;
1.) Is HDR a real thing, or just marketing BS?
2.) What is the difference between these HDR’s, (see attached screenshots)?

1.). Yes, HDR is a real thing for dashcams, but only works well on dashcams with Starvis 2 image sensors. On other dashcams it is not really worth worrying about.

2.) No real difference, just marketing terms trying to make the cameras look different, except when the camera has a Starvis 2 image sensor, hence the "(A139 Pro) “HDR NIght Vison 2.0”, which is genuinely better in many lighting conditions, but not always.

 

[Nigel]

Since 2020 I've tried WDR on Viofo dash cams, and I have never observed an improvement in image quality.
I wish WDR is discontinued in all future Viofo dash cams, and maybe even removed from all past Viofo dash cams.
Here's a clip from March 11, 2020 with the A129 Pro;

Viofo dashcams are nearly always better with WDR turned off. But in reality, all dashcams use WDR even if it is turned off, it is just a matter of how much WDR they use. A dashcam without WDR would look like GoPro video, far too much contrast to read any of the number plates that are in shadow.

 

[OldEastSider]

A very interesting discussion.

But I'm confused. If Viofo's official position is that WDR is "almost useless", as stated above, why is it built into their very own WM1?

 

[kamkar]

Well you have to make what people will buy, even if it can be a bit silly with more knowledge.

 

[VIOFO-Support]

A very interesting discussion.

But I'm confused. If Viofo's official position is that WDR is "almost useless", as stated above, why is it built into their very own WM1?

Indeed, the WDR has no such huge effect as HDR, but it also plays an important role in balancing exposure in the change of bright and black areas to make the videos clearer. We have different models of products to satisfy different desires. Such as A139Pro 4K can provide very clear videos with high configuration. At the same time, the price of it will go to a high level.🤔

 

[Kremmen]

As I've posted many times, I've tried HDR on my A119V3 and, in my opinion, it degrades the daytime footage. Each time a new firmware was released I installed and tested it but always went back to firmware 1.03, WDR off.

1.03 always gave me better static screenshots, which is what I mainly use the footage for, than any subsequent firmware, even with HDR turned off.

Even on the Viofo HDR introduction webpage, there are 2 screenshots of HDR on and off and the 'on' screenshot shows an out of focus "V" on the concrete post which is far clearer on the 'off' screenshot.

True HDR is implemented in A119 V3

VIOFO A119 V3, provides Firmware that supports HDR for customer.

viofo.com

However, later firmware with HDR does satisfy other users, just my personal preference.

 

[bobcat]

Great topic for discussion! I've been recently testing a Starvis 2 dashcam and got very interesting results on the HDR.
My basic conclusion is : if the picture "beautyfullness" matters to you, turn on HDR, however if you need to capture a sharp image, keep it off. Starvis 2 indeed captures 2 frames, but they are not captured at the same time (aka half of pixels overexpose and half of pixels underexpose), it captures 2 consecutive images in a very short timeframe, but add low light conditions and motion, your in for some artifacts that may lead to license plates being less readable for example.

 

[Dadi_T]

but add low light conditions and motion, your in for some artifacts that may lead to license plates being less readable for example.

Can you put some sample footage/pictures to prove your statement?
Until now, all the license plates captured on this forum, with low light conditions and motion, are with HDR dashcams. And a lot of evidence is here, on the forum.

 

[bobcat]

Can you put some sample footage/pictures to prove your statement?
Until now, all the license plates captured on this forum, with low light conditions and motion, are with HDR dashcams. And a lot of evidence is here, on the forum.

The HDR helps in the scenario where you have extreme contrasts between the subjects and does the opposite were there is not much contrast in the scene. Now for the majority of the countries this is a good thing, since license plates are usually black on white, however in some states in the US it is a different story 🙂

Below is a really good example. I'm driving through the parking lot with camera pointed directly at the SUV, which ideally would offer the highest chance of capturing the plate of that car but what we see is that only the white license plate is readable. That is because after over-imposing 2 frames into one only the high contrast information survives. As for all other license plates in this shot, they are not readable because of HDR artifacts. Without HDR you'd get higher probability of reading those plates (or at least capturing 1 frame that would give it a chance) since only the motion blur will be your issue and not the extra artefacts.

I've also outlined an area on the black car where you clearly see 2 images over imposed on the darker side of the car against concrete in the background. Notice how the same is not happening right above the concrete since now we are in the high contrast zone. These are the artefacts I'm talking about, and this is happening because HDR takes 2 consecutive shots that will have slightly different framing due to delay in timing and exposure. The only real viable HDR solution would be recording data at extremely high color bit rate and doing the processing at the back end (think Hasselblad) but we all know no one will be buying a 2000$ dash cam.

And again, this is only a problem for some states license plates, while in countries with standard black on white plates, HDR might offer higher chance of capturing the plate. So to sum-up, HDR is not a one stop shop solution for every scenario.

 

[Dashmellow]

The HDR helps in the scenario where you have extreme contrasts between the subjects and does the opposite were there is not much contrast in the scene. Now for the majority of the countries this is a good thing, since license plates are usually black on white, however in some states in the US it is a different story 🙂

You are leaving out some important information about why HDR plate capture works better in European nations than in countries like the U.S., Canada and Mexico. European license plates and their corresponding numbers and letters are much larger than license plates in the Western Hemisphere and in some of these countries they are also much more reflective than U.S. plates.

Also, the example you've provided inside the garage has very uneven lighting from car to car. It has been well established at this point that night time plate capture using HDR works best when two cars are approaching each other head on traveling in opposite directions and well illuminated by your vehicle's headlights. Making a slow sweeping turn in a dimly lit garage is much less likely to clearly capture plate numbers regardless of contrast and more likely to show motion blur and an out of register double exposure from the two super-imposed HDR images.