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Author Topic: HDR  (Read 7266 times)
marvpelkey
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« on: November 13, 2012, 10:53:19 PM »
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Trying to get a handle on HDR as I have little to no experience on this topic.

Given that an images max DR is restricted by pure black at one end and white at the opposite, am I correct that putting a "scene" (by way of multiple image exposed differently) through the HDR process only results in finer levels of tone? In other words, it doesn't make the ruler any longer, it just divides the ruler into finer increments? Presumably, this is impacted by the DR of the medium (i.e. monitor, print etc) as well.

Or, if a camera sensor is capable of say, twelve stops, can HDR actually result in an image that is, say, thirteen stops (so the ruler actually lengthens)? And if this is the case, what is the limit?

Have tried reading up on this subject, but so far it's a bit unclear.

Marv
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ErikKaffehr
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« Reply #1 on: November 13, 2012, 11:32:17 PM »
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Hi,

You make the ruler longer. There is no limit, but there are a lot of issues. Good HDRs are not easy to make.

HDR is really a two step process:

1) You combine several images into a HDR image

2) You "tone map" the image so it can be presented on a device with a normal dynamic range.

The tone mapping process decides if you get a natural looking image or a "grungy" one.

I very seldom use HDR, because I generally feel that the DR of todays cameras is ample.

Check out these articles describing the use of HDR mapping on a single RAW image.

http://echophoto.dnsalias.net/ekr/index.php/photoarticles/63-lot-of-info-in-a-digital-image

http://echophoto.dnsalias.net/ekr/index.php/photoarticles/61-hdr-tone-mapping-on-ordinary-image

There was a good discussion around the issue here on LuLa forums: http://www.luminous-landscape.com/forum/index.php?topic=60082.0

Check this PDF by "leuallen" describing tone mapping in SNS HDR: https://docs.google.com/file/d/0B8ETvhCd81aFMTUyMTU4OTctZGQxZS00NTBmLWE5MDgtMDIwNWM1ODA3M2I4/edit?pli=1

Best regards
Erik

Trying to get a handle on HDR as I have little to no experience on this topic.

Given that an images max DR is restricted by pure black at one end and white at the opposite, am I correct that putting a "scene" (by way of multiple image exposed differently) through the HDR process only results in finer levels of tone? In other words, it doesn't make the ruler any longer, it just divides the ruler into finer increments? Presumably, this is impacted by the DR of the medium (i.e. monitor, print etc) as well.

Or, if a camera sensor is capable of say, twelve stops, can HDR actually result in an image that is, say, thirteen stops (so the ruler actually lengthens)? And if this is the case, what is the limit?

Have tried reading up on this subject, but so far it's a bit unclear.

Marv
« Last Edit: November 14, 2012, 12:24:27 AM by ErikKaffehr » Logged

hjulenissen
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« Reply #2 on: November 14, 2012, 03:06:35 AM »
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Marketing material from a HDR display:


The ruler really is endless.
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marvpelkey
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« Reply #3 on: November 14, 2012, 09:26:49 PM »
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Thank you both for very detailed and informative answers.

Marv
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popnfresh
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« Reply #4 on: December 04, 2012, 04:00:04 PM »
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More important, imo, than how much detail can be retained at the extreme ends of the shadows and highlights in an HDR composite is how it changes the appearance of the scene photographed. By averaging out the luminance of a scene, HDR tends to destroy any unique quality of the light that may have been captured by a single exposure. For that reason, HDR tends to, but not always, look rather manipulated and artificial. It's the main reason I never use it.
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Tony Jay
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« Reply #5 on: December 04, 2012, 04:40:26 PM »
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More important, imo, than how much detail can be retained at the extreme ends of the shadows and highlights in an HDR composite is how it changes the appearance of the scene photographed. By averaging out the luminance of a scene, HDR tends to destroy any unique quality of the light that may have been captured by a single exposure. For that reason, HDR tends to, but not always, look rather manipulated and artificial. It's the main reason I never use it.

Can't completely agree with this statement.
One can make HDR look terrible and 'manipulated'.
I use HDR for the opposite purpose very successfully and have posted HDR images (with huge DR in the captured scene) on this forum that were not picked as HDR images until I fessed up - that is successful HDR (for me) - the finished product look just like it should.

Using 32-bit TIFF files in Lightroom to do the tonal manipulation has dramatically simplified the whole process of achieving natural looking results.

Tony Jay
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KeithR
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« Reply #6 on: December 04, 2012, 05:35:31 PM »
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HDR can be either real good or real bad. It's all subjective.
Here's a link to an architectual photographer that uses HDR and gets great results without going over the top. I have no connection to him but saw his work and comments about his use of HDR on another forum.
http://www.larryandersonphotography.com/
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« Reply #7 on: December 04, 2012, 06:56:41 PM »
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HDR can be either real good or real bad. It's all subjective.
Here's a link to an architectual photographer that uses HDR and gets great results without going over the top. I have no connection to him but saw his work and comments about his use of HDR on another forum.
http://www.larryandersonphotography.com/

I agree that Anderson's work is some of the best examples of HDR around. It's very clean, professional work. The quality of light, however, especially in the outdoor shots still looks homogenized to me. For indoor architectural or commercial work I can see that that wouldn't necessarily be a problem--maybe even an advantage in many instances. But for fine art landscape photography, preserving the subtle quality of light in the scene is important, at least to me.
« Last Edit: December 04, 2012, 06:59:17 PM by popnfresh » Logged
Slobodan Blagojevic
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« Reply #8 on: December 04, 2012, 07:37:30 PM »
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Off-topic: is this the good, old "popnresh" reborn or indeed a brand new newbie?

Inquiring minds want to know Smiley
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Slobodan

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« Reply #9 on: December 04, 2012, 09:22:56 PM »
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Off-topic: is this the good, old "popnresh" reborn or indeed a brand new newbie?

Inquiring minds want to know Smiley

I'm new here. I take it there used to someone else with this alias. They must not be around any longer otherwise I assume I wouldn't have been able to register it.
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Schewe
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« Reply #10 on: December 04, 2012, 09:41:10 PM »
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I'm new here. I take it there used to someone else with this alias.

Not for nothing but most people sign on to LuLa with something resembling a real name (notice the other screen names in the thread). You tend to be taken just a bit more seriously than trying to hide behind an anonymous screen name. If nothing else, at least sign your posts with a first name cause calling you "popnfresh" is pretty stupid. What, are you a baker?
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popnfresh
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« Reply #11 on: December 04, 2012, 09:48:21 PM »
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Not for nothing but most people sign on to LuLa with something resembling a real name (notice the other screen names in the thread). You tend to be taken just a bit more seriously than trying to hide behind an anonymous screen name. If nothing else, at least sign your posts with a first name cause calling you "popnfresh" is pretty stupid. What, are you a baker?

Not my concern. And, no. I work in IT.
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Schewe
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« Reply #12 on: December 04, 2012, 09:49:52 PM »
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Not my concern.

Actually it should be if you want to fit in here...if not, you prolly won't he around long. Just sayin'
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popnfresh
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« Reply #13 on: December 04, 2012, 09:57:38 PM »
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Actually it should be if you want to fit in here...if not, you prolly won't he around long. Just sayin'

Are you like the forum police or something?
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Schewe
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« Reply #14 on: December 04, 2012, 10:03:02 PM »
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Are you like the forum police or something?

Sometimes...yes. If you don't know who I am, I guess you don't really know much about LuLa, huh? You sure you wanna hang out here?
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popnfresh
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« Reply #15 on: December 04, 2012, 10:04:26 PM »
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Sometimes...yes. If you don't know who I am, I guess you don't really know much about LuLa, huh? You sure you wanna hang out here?

I think you seriously need to chill out.
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Schewe
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« Reply #16 on: December 04, 2012, 10:08:26 PM »
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I think you seriously need to chill out.

And, I think you need to introduce yourself to the group...again, what are you, a baker?

Just so you know, it's useful if newbies get to know the community before launching themselves as some sort of expert. If you hang behind an anonymous screen name, it says something about you. Who are you and what credence do you deserve? LuLa is just like any other community...it keeps a sharp eye on newbies and how they respond and behave. Considering you joined yesterday, so far you don't have much of a track record (although your posts have generally been useful).
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popnfresh
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« Reply #17 on: December 04, 2012, 10:11:29 PM »
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And, I think you need to introduce yourself to the group...again, what are you, a baker?

Just so you know, it's useful if newbies get to know the community before launching themselves as some sort of expert. If you hang behind an anonymous screen name, it says something about you. Who are you and what credence do you deserve? LuLa is just like any other community...it keeps a sharp eye on newbies and how they respond and behave.

I'm not the one having behavioral issues at the moment. I was having an interesting conversation with others on this thread and suddenly you appear out of nowhere and you're all over my ass about my alias. I mean, seriously, what is your problem, dude?
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Schewe
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« Reply #18 on: December 04, 2012, 10:49:08 PM »
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I mean, seriously, what is your problem, dude?

Who are you? And why are you here? It makes a difference doooode...introduce yourself (or don't and that will be telling).
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popnfresh
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« Reply #19 on: December 04, 2012, 10:53:12 PM »
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Who are you? And why are you here? It makes a difference doooode...introduce yourself (or don't and that will be telling).

This may come as a shock, but I don't answer to you.
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