Dynamic Range Compression Equivalent In Video

[The Computer Audiophile]

Hi Guys - I know video has dynamic range, but I'm trying to figure out if there is an equivalent to audio dynamic range compression in video. 

 

This may help people realize the damage done to compressed audio, if they could see an equivalent process done to video. 

 

Ideally, I could compress the dynamic range of video as much as some audio, and it would be super dark or super light etc...

 

Anyone?

[rickca]

All you need to do is watch a Comcast or AT&T so-called HD channel and compare it to a Blu-Ray.  Compression destroys a lot of the detail in near-black.

 

Here's a link to a rather scientific article

http://www.root6.com/support-2/tips/perceptual-video-quality-and-compression-psnr-measurements/

[esldude]

That's data compression and I agree it is obvious.  Chris is taking dynamic range compression.  I've seen processing for still photos that does that. 

[rickca]

OK you're right.  So what is really analogous in video is HDR vs SDR.  HDR is all the rage in the latest TVs, whether it is HDR10 or Dolby Vision or HLG.

[sphinxsix]

You can also easily demonstrate the importance of video dynamic range using stills. Eg.

As for audio DR compression - it would obviously be the best proof of damage it does to the music if they could simply hear it. In my experiance only slightly higher percentage of people can see what picture quality is about than hear what sound quality is about (as far as subtle differences are concerned) but I think you may be right - it may be easier to demonstrate differences like that using pictures (moving or still ones). Both skills (ability to hear/see the subtle differences) require going through some perception 'education' process IMO and not everybody (to put it mildly) is ready and willing to do that.

[esldude]

I think this would apply.  One photo as it was taken.  And one where I have adjust level thresholds for low and high.  I reduced the level for top brightness in essence shrinking light to dark range by 1/3 (about 9 db if we were talking about music).  Nearly everything becomes bright the way nearly everything becomes loud with music.  You lose lots of detail just shrinking the image size as this was originally a 16 megapixel image. Even then compression of levels has an obvious terrible effect on available features that are left.

 

I think this is appropriate.  Like sound a little bit seems brighter and more vibrant.  Eventually it becomes too much. It would appear to me our eye is perhaps more sensitive to this than our ear. 

 

Well sphinxsix sort of beat me to it though my example is more extreme kind of like nearly all current commercial albums.

 

[The Computer Audiophile]

1 minute ago, esldude said:

I think this would apply.  One photo as it was taken.  And one where I have adjust level thresholds for low and high.  I reduced the level for top brightness in essence shrinking light to dark range by 1/3 (about 9 db if we were talking about music).  Nearly everything becomes bright the way nearly everything becomes loud with music.  You lose lots of detail just shrinking the image size as this was originally a 16 megapixel image. Even then compression of levels has an obvious terrible effect on available features that are left.

 

I think this is appropriate.  Like sound a little bit seems brighter and more vibrant.  Eventually it becomes too much. It would appear to me our eye is perhaps more sensitive to this than our eye. 

 

 

This is exactly what I was seeking. I can see people going for a brighter image, much the same way they go for a louder sound. But, when given the chance to pause the action with a photo, it's easy to see the image on the right sucks. 

[iansen]

Quote

I can see people going for a brighter image, much the same way they go for a louder sound.

 

True. Indeed over here in London, England if you walk into any TV showroom you are confronted with a barrage of screens - all with the brightness and colour turned up - vying for your attention. Often, the screens are displaying animations or CGI-heavy films which not only accentuate and exaggerate said brightness and colour but also prevent the viewer from making any proper assesment of colour accuracy.

 

Placing my iPhone5 against my Pioneer Kuro Plasma Screen: and the colours on my phone appear vivid and enticing, and my television appears dull and drab in comparison. It's only when I move my eyes away from the screens and look at a tree through my window that I realise which of the screens is a more accurate representation of the real world.

[Abtr]

3 minutes ago, iansen said:

... Placing my iPhone5 against my Pioneer Kuro Plasma Screen: and the colours on my phone appear vivid and enticing, and my television appears dull and drab in comparison. It's only when I move my eyes away from the screens and look at a tree through my window that I realise which of the screens is a more accurate representation of the real world.

 

But I wouldn't call a high dynamic range sound recording "dull", on the contrary..

[sphinxsix]

1 hour ago, iansen said:

 

True. Indeed over here in London, England if you walk into any TV showroom you are confronted with a barrage of screens - all with the brightness and colour turned up - vying for your attention. Often, the screens are displaying animations or CGI-heavy films which not only accentuate and exaggerate said brightness and colour but also prevent the viewer from making any proper assesment of colour accuracy.

 

Placing my iPhone5 against my Pioneer Kuro Plasma Screen: and the colours on my phone appear vivid and enticing, and my television appears dull and drab in comparison. It's only when I move my eyes away from the screens and look at a tree through my window that I realise which of the screens is a more accurate representation of the real world.

Kuro series were great. I own top series Panasonic plasma (THX certified) and I know exactly what you mean. I'm not sure contemporary LCD/LED screens are as good as late plasmas. Some years ago I used to do an exercise - just for fun : while walking along tens of TVs in the local Media Markt I tried to guess (in just 2 or 3 seconds) whether the screen I was looking at was plasma or LCD. Then I checked it out looking at the price/specification tag. I usually was right in 90%. Considering the fact that most of the screens I was looking at were heavily 'tuned up' - not bad, I believe

[unfa]

Hi!

 

This is my first post here I'm a musician, but also a graphic designer and I work with video too.

 

I think there's some confusion in this thread, so I'd like to try and clear that up.

 

Dynamic range compression in audio is turning down volume of the signal when it gets louder than a given threshold. However a key factor is delayed reaction - otherwise it's be identical to distortion (say - soft clipping).

 

An overexposed image is not a video analogue to audio dynamic range compression - it's an image analogue to audio distortion. In photography that's even called clipping.

 

If we translate the time dimension of audio signal to spatial dimention of an image - a composited HDR image might be a good analogue - it's using some tricks to squeeze a high dynamic range into a smaller one, while preserving the detail in bright (and dark) areas - it's a technique used to prevent clipping (a bit like what audio limiters do).

 

An automatic exposure in video cameras is what I think is the closest thing to audio dynamic range compression, as it includes a time factor and reacts similarly.

 

Also - dynamic range compression for audio is just a tool to control the sound levels. It's been used for decades and is essential in making well sounding recordings, but it can be poorly used as well. It can also be abused for creative effects.

 

I personally prefer when the music has more headroom to breathe, and that's what I try to do with my productions.

 

Cheers!

[sandyk]

On ‎4‎/‎21‎/‎2017 at 6:31 AM, The Computer Audiophile said:

This is exactly what I was seeking. I can see people going for a brighter image, much the same way they go for a louder sound. But, when given the chance to pause the action with a photo, it's easy to see the image on the right sucks. 

 In this case by simply increasing HF detail a little in the DIGITAL

domain.

The differences are best seen at the direct links

https://imageshack.com/a/img922/3521/hA7X7H.png

https://imageshack.com/a/img923/5024/NMu0jF.png