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Author Topic: A Thank for the HDR Plea  (Read 7535 times)
NikoJorj
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« on: December 21, 2009, 03:35:04 PM »
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Many thanks to Alexandre to remind us that well-done tone mapping is the basis of photography, in a very clear and brilliant way!  (enfin, normal, il est normalien  )
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Nicolas from Grenoble
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Tom Montgomery
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« Reply #1 on: December 21, 2009, 07:14:03 PM »
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It is helpful to be reminded from time to time that HDR is a process of compression, and not expansion!  And, just as in audio, overenthusiastic tweaking of the compressor controls can result in horrible output.  

I think that HDR gets the bad rep partly because it is mostly the bad examples that are so labelled.  The good HDR images often don't mention it.

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Eric Myrvaagnes
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« Reply #2 on: December 21, 2009, 08:11:58 PM »
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Alexandre indeed made the case beautifully for HDRdone right. Nice essay!
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wolfnowl
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« Reply #3 on: December 21, 2009, 11:57:48 PM »
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Thanks indeed!

Mike.
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Alexandre Buisse
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« Reply #4 on: December 22, 2009, 01:32:06 AM »
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I'm glad everyone seemed to enjoy it, and quite a few people said they would give HDR another chance as a consequence of reading it. So, well, you're very welcome.
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NikoJorj
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« Reply #5 on: December 22, 2009, 02:44:41 AM »
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May be I shouldn't step too far in the kitchen recipe territory, but when you say that :
[!--quoteo(post=0:date=:name=Alexandre Buisse)--][div class=\'quotetop\']QUOTE (Alexandre Buisse)[div class=\'quotemain\'][!--quotec--]By its very nature, HDR processing will significantly increase noise, especially in the shadows[/quote]
Wouldn't you think that on the other hand, with enough overexposed captures, HDR may actually diminish noise?
I'm thinking to the way Guillermo Luijk's ZeroNoise works, replacing noisy shadow pixels from the nominal exposure with cleaner ones from an +4EV overexposed capture.
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Nicolas from Grenoble
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pedro.silva
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« Reply #6 on: December 22, 2009, 04:38:54 AM »
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nice plea indeed, but... is the typo on the front page intentional?  if not, perhaps it could be fixed... please!
cheers,
pedro
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Graeme Nattress
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« Reply #7 on: December 22, 2009, 07:10:28 AM »
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I like well done HDR, but really don't like traditional tone mapping techniques and the artifacts they induce. To me HDR should look like well directed fill lighting. Thanks for showing some shots that looked just like that.
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rustyjaw
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« Reply #8 on: December 22, 2009, 04:01:26 PM »
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As a huge proponent of HDR as a techinique, and not as a look, I'm very happy to see this article appear on a 'serious' photography site. Well done.

However, I don't quite understand this line in the article:

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By its very nature, HDR processing will significantly increase noise, especially in the shadows.

If the original exposures are properly executed, if they cover a sufficient portion of the dynamic range of the scene, then noise will not be a problem.
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craigwashburn
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« Reply #9 on: December 22, 2009, 05:55:34 PM »
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Quote from: rustyjaw
As a huge proponent of HDR as a techinique, and not as a look, I'm very happy to see this article appear on a 'serious' photography site. Well done.

However, I don't quite understand this line in the article:



If the original exposures are properly executed, if they cover a sufficient portion of the dynamic range of the scene, then noise will not be a problem.

Actually, there are many scenes where to do this would be impractical - a night sky for example, or a situation that simply is dark.  I can recall a theatre I photographed that was painted entirely black and had black furniture etc.

It also depends on the tone mapping algorithm used, and the various parameters it is invoked with.  Use a shadow point cutoff in your initial tone mapping, or choose something like one of the newer "fusion" algorithms that seems to handle large areas of shadow more intelligently if you're having problems with shadow noise.  Or, composite in one of the exposures.

HDR (actually, we should say tonemapping...) is like an ultra-wide angle lens.  Just a tool - Useful, highly effective at times.  When used improperly or by a hand with, lets say, not very good taste, it can be ugly.



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rustyjaw
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« Reply #10 on: December 22, 2009, 06:21:31 PM »
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Quote from: craigwashburn
Actually, there are many scenes where to do this would be impractical - a night sky for example, or a situation that simply is dark.  I can recall a theatre I photographed that was painted entirely black and had black furniture etc.

It also depends on the tone mapping algorithm used, and the various parameters it is invoked with.  Use a shadow point cutoff in your initial tone mapping, or choose something like one of the newer "fusion" algorithms that seems to handle large areas of shadow more intelligently if you're having problems with shadow noise.  Or, composite in one of the exposures.

Yes, I agree with what you are saying, perhaps I should have been more specific that what I took issue with was the phrase "By its very nature" - I don't believe that this is true, it happens to be true when circumstances prevent exposures that cover the dynamic range one wishes to capture (as in your first example), or if the parameters are pushed too far, etc. But none of this is inherent to HDR. If anything, HDR is a great tool for reducing noise in shadows, than would be possible with one exposure.
« Last Edit: December 22, 2009, 06:22:15 PM by rustyjaw » Logged

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tim wolcott
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« Reply #11 on: December 22, 2009, 09:14:28 PM »
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Quote from: NikoJorj
Many thanks to Alexandre to remind us that well-done tone mapping is the basis of photography, in a very clear and brilliant way!  (enfin, normal, il est normalien  )


Although its a nice image, but hardly needed HDR for that.  I could have capture that with my Phase camera system.  This is what I find funny about the Pixel counters, you always want a way to fake the system, instead of waiting for little things to happen in the shot like a cloud to move and block more of the highlights and make the shadows and highlights closer together.

By waiting for just the right circumstances you will always get a better images the correct way to capture the image.

Your pursuit of finding everything possible to know about things you either can't control not use to your advantage is hilarious.

Why not spend more time studying better lighting, composition, picking the right depth of field, choosing the right lens for the job ect.  This will help you more than wasting your time, because nothing will ever replace the proper way to shoot an image.  No amount of gimmicks will help and produce great images.

So here is an image captured without HDR and shot the right way.  I waited 6.2 hours for this to become just perfect with the right cliffs and trees lit up all together. Tim

 

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Jeremy Payne
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« Reply #12 on: December 22, 2009, 09:25:48 PM »
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Quote from: tim wolcott
... the correct way to capture the image ...

Sorry, but who anointed you the czar of correctness?

HDR techniques utilizing tone-mapping and multiple exposures have been around since the 1930s ... have you heard of Charles Wyckoff?

Live and let live, man ...
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DarkPenguin
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« Reply #13 on: December 22, 2009, 09:54:37 PM »
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Quote from: Jeremy Payne
Sorry, but who anointed you the czar of correctness?

I believe he did.
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tim wolcott
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« Reply #14 on: December 22, 2009, 10:01:23 PM »
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Quote from: Jeremy Payne
Sorry, but who anointed you the czar of correctness?

HDR techniques utilizing tone-mapping and multiple exposures have been around since the 1930s ... have you heard of Charles Wyckoff?

Live and let live, man ...

I will still say, most images captured with HDR could have been captured with single exposure if you are willing to wait.  I want to see the image printed at 50 inches.  Then maybe I'll change my thoughts.  We all want more dynamic range, but as the new chip coming with amazing range no one will remember HDR.  Its not that it shouldn't be done.  Its just that its being used as a novelty.

Its true that mapping has been around for a very long time, hell we had to use to invent the printing process you are using today and many others that I have invented.

I wasn't trying to say that I'm the czar, but time could be spent better.  Isn't the goal to shoot better images the way to proceed.  Learning to stitch an image like what a banquet camera sees would make a person portfolio better.  Tim
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Alexandre Buisse
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« Reply #15 on: December 23, 2009, 03:55:05 AM »
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Quote from: rustyjaw
Yes, I agree with what you are saying, perhaps I should have been more specific that what I took issue with was the phrase "By its very nature" - I don't believe that this is true, it happens to be true when circumstances prevent exposures that cover the dynamic range one wishes to capture (as in your first example), or if the parameters are pushed too far, etc. But none of this is inherent to HDR. If anything, HDR is a great tool for reducing noise in shadows, than would be possible with one exposure.

You are correct, it was bad wording on my part, and you are far from being the first to call me on it.
I agree that HDR reduces noise compared to what you would have obtained if you had stretched a single exposure into the same overall contrast values. But what I meant is that, since you are going to pull details from the shadows, unless you have an extremely wide bracket set, you are going to have more noise than your "average" photo.
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Alexandre Buisse
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« Reply #16 on: December 23, 2009, 04:08:51 AM »
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Quote from: tim wolcott
Although its a nice image, but hardly needed HDR for that.  I could have capture that with my Phase camera system.

To which image are you referring? And I always find it funny when people say things like that without having seen the original scene nor the raw files. You have no idea how much contrast the original scene had.



Quote
This is what I find funny about the Pixel counters, you always want a way to fake the system, instead of waiting for little things to happen in the shot like a cloud to move and block more of the highlights and make the shadows and highlights closer together.

Pixel counters? Where did you see any of that in the article? And how is using those techniques "faking the system"?

As for waiting for the cloud to block the sun, that can work sometimes but it isn't guaranteed at all and then light conditions will have changed. What if the scene I want to record is the one I see in front of me now? If you look at the images in the article, the sun is almost always already behind the clouds. What then, am I just supposed to wait for sunset?



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By waiting for just the right circumstances you will always get a better images the correct way to capture the image.

Says you. I disagree. What if the right circumstances are now but the camera can't record it correctly (yes, even phase one backs have finite dynamic range)? No one has the pretension to know what the "correct" way to do anything is. All HDR does is offer one more tool to capture the image, nothing more.


Quote
Your pursuit of finding everything possible to know about things you either can't control not use to your advantage is hilarious.

And you message is more than a little insulting.


Quote
Why not spend more time studying better lighting, composition, picking the right depth of field, choosing the right lens for the job ect.  This will help you more than wasting your time, because nothing will ever replace the proper way to shoot an image.  No amount of gimmicks will help and produce great images.

All of this is completely orthogonal to the use of HDR. You can have the perfect light, composition, depth of field and lens but still not be able to capture the image in a single exposure. Which is when HDR becomes useful.


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So here is an image captured without HDR and shot the right way.  I waited 6.2 hours for this to become just perfect with the right cliffs and trees lit up all together. Tim

That's a nice image. But because you waited and managed to get a capture with a single exposure doesn't mean that waiting will always make someone be able to capture a scene with a single exposure. Again, what if the scene I wanted to capture was the one from 6.2 hours ago when dynamic range was too big for your sensor?
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Alexandre Buisse
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« Reply #17 on: December 23, 2009, 04:14:19 AM »
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Quote from: tim wolcott
I will still say, most images captured with HDR could have been captured with single exposure if you are willing to wait.

And I will say that first, this simply isn't true, unless you are waiting for sunset, and second, that the scene will, by definition, be different. So no, except in very rare cases, you can not capture the same scene by waiting than with HDR.


Quote
I want to see the image printed at 50 inches.  Then maybe I'll change my thoughts.  We all want more dynamic range, but as the new chip coming with amazing range no one will remember HDR.  Its not that it shouldn't be done.  Its just that its being used as a novelty.

And that's exactly what I want to "fight" with this article. I would be more than happy to ditch HDR if sensors suddenly had an amazing dynamic range. But it so happens that today, I encounter many scenes with too much contrast for my DSLR to handle, so I have to find a way to capture them with the tools I have right now. And it happens to be HDR.


Quote
Its true that mapping has been around for a very long time, hell we had to use to invent the printing process you are using today and many others that I have invented.

I wasn't trying to say that I'm the czar, but time could be spent better.  Isn't the goal to shoot better images the way to proceed.  Learning to stitch an image like what a banquet camera sees would make a person portfolio better.  Tim

I agree that there are many important things to learn before HDR, but that doesn't mean that HDR is a worthless or useless technique, like you seem to imply.
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MarkL
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« Reply #18 on: December 23, 2009, 06:39:33 AM »
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HDR is just another tool and just like the saturation slider, is all too frequently tastelessly abused imo, it's really no different to the velviascapes with reds that never existed and b&w where the sky is almost black. The real issue with HDR is that you have to work hard to make it look natural rather than the other way around.

Many strong photographs are strong because they are dramatic so joe bloggs tries to add drama to his with extreme contrast, over the top HDR and saturation. If that is how people want their photographs to look like than that is up to them I guess but I can't help feeling it reduces the credibility of landscape photography as a whole in the eyes of non-photogs.

I will continue to exposure blend to compensate for the limitations of my gear rather than use it for any kind if effect. I don't have much interest in HDR.
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Graeme Nattress
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« Reply #19 on: December 23, 2009, 07:08:46 AM »
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Quote from: tim wolcott
We all want more dynamic range, but as the new chip coming with amazing range no one will remember HDR.

Indeed newer sensors have lower noise / higher dynamic range.

However, how do you map that dynamic range available into the limited range of displays or a print? You can go blending by hand in Photoshop, or you can do some luma masking. Or you could use a traditional HDR tonemapping technique, or you could use some HDR technique that doesn't look all weird and garish.

Either way, you have to remap the tones in the image in a non-linear manner that produces results beyond the limits of a single toning curve. And at that point, HDR tonemapping is going to not just become more popular, but practically necessary or else the extra dynamic range on the sensor will be wasted.

Graeme
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