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Can someone please explain HDR, tone-mapping, etc. to me?
#1
What's with all the recent hubbub about HDR and tone-mapping techniques? I mean, I understand the aesthetic appeal of the very high-dynamic range images, with that charcoaly / painterly look, but why has this suddenly become so widespread?

Heck, at a more basic level, we were using inverted-overlay contrast masks to improve dynamic range way back in the "good old days" of Photoshop LE (I know, some of you aren't old enough to remember that one.) It doesn't seem the new methods are much better at controlling halos, so why all the fuss?

More specifically, what is "tone mapping" compared to a simple contrast mask or high-pass filtering? Just a more complicated way of skinning the cat? Or am I missing something? Is there a reason to use this technique for "normal" images, rather than using the super-simple yet very effective highlight/shadow tool in PS?

And what's the rationale for using multiple in-camera exposures, rather than the simpler technique of processing multiple "exposures" from a single RAW file?

Not being negative, just trying to understand the sudden widespread adoption and the appeal of newer techniques.
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#2
If a single exposure has zero detail in the shadow areas, or completely blown highlights, you can't really fix it in post processing. You might get some usable data if you shot in RAW, but it still won't be of the same quality as the rest of the photo.


I think most HDRs are done for the effect rather than for basic image quality.
It's over-used, but signs point to people being already bored with the extreme HDR 'look' and returning to more natural results. A year ago it was really bad.
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#3
G posted here a how to and give some links about HDR.

http://www.shuttertalk.com/forums/viewtopic.php?id=5232

We have tried it and the techique works fine for certain pictures specially when you want to get detail in the dark areas, and textures in the high lights basically.

Here is a link with some of my pictures I have worked with this technique, most of them are processed with the program photomatix.

http://www.flickr.com/photos/perikita/tags/hdr/

At the beginning it was one of the best programs, now there are a lot more. CS3 has now knew features not described in G's writing.


Edit. Sorry forgot the link of G's post.
A work of art which did not begin in emotion is not art.
Paul Cezanne
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#4
KeithAlanK Wrote:If a single exposure has zero detail in the shadow areas, or completely blown highlights, you can't really fix it in post processing. You might get some usable data if you shot in RAW, but it still won't be of the same quality as the rest of the photo.
Good points.


KeithAlanK Wrote:A year ago it was really bad.
I'm apparently a bit behind then, but glad I missed the onslaught! Wink




Irma Wrote:the techique works fine for certain pictures specially when you want to get detail in the dark areas, and textures in the high lights
Thank Irma; those are helpful. Also the link on your HDR test page to the Luminous Landscape article on using CS2.
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#5
Yep. I reckon we see all the overdone ones because many folks purposefully use HDR just to get that generic, seen-it-before feel. It's a bit like any other fad when it's being pursued for this end, perhaps: haven't we all been bored by the similar "common-herd" fads of, for example, long-exposure waterfalls, fisheye lenses, and a million other things? It becomes a bit slavish when everyone seems to be on the same bandwagon, I suppose. And, I'd better add, I'm guilty too, as all of these are fun and with dramatic results.
I think that when the pendulum swings back the other way, we'll start to see more subtlety and knowlegeable use of all that's in "the HDR workflow": the fact that we've got digital sensors and not film really assists us in this area: with digital, the tolerances are much greater when one overexposes...in other words, there's a considerable retention of highlight detail that often would be lost if one had film, particularly slide film. One can overexpose by maybe 2 stops but still find that details remain with careful raw conversion. With film, this would not usually be possible or practical. On the other hand, shadow detail blocks out moreso with digital, because it is not film and does not behave in the same way. A good tip , then, might be to make a point of slightly overexposing all one's shots if range of lighting is a constant concern...on the grounds that you'll lose out more if you underexposed by the same amount. A good example of working the media and making use of increased dynamic range would be, say, in a landscape:
Scenario 1(film): meter off the grass to get 18% grey reflectivity, then realise that the dynamic range of a couple of stops means that you have to go for any number of grads, ND grads and warm-ups to expose the sky correctly. IF one has learnt about light and how to use a spot meter, one can craft the shot.
Scenario 2(digi): (one approach): meter in the same way, add a stop and a half exposure compensation, shooting in raw: you'll still have, without grads, sufficient capture of the dynamic range to bring out most of the sky without blocking up the shadows in the foreground, even if shooting one raw. With a bit of bracketing, you've quickly got the whole range covered, so that the HDR image is a mighty fine tool. If then one is careful not to overdo the saturation, the result can easily appear quite masterful, as if one has spent ages spotmetering with a probe from the film plane, in emulsion terms! I confess I'm even getting a little lazy in my exposure, when doing landies, for exactly that reason. I'll rely on the sensor capturing more highlight detail, so making sure I just tweak my exposure by + half or a stop. Now here's the thing: by shooting in raw, then doing a lo-contrast conversion, I then have an image from one exposure that has ALREADY captured a higher dynamic range than a stock, straight-to-jpeg shot. OK, it's not an "HDR" ...but IS an image with increased dynamic range. Then of course this means that i have to faff around with burning-in, contrast and saturation...but at least I have the information in the capture.
All my stuff is here: www.doverow.com
(Just click on the TOP RIGHT buttons to take you to my Image Galleries or Music Rooms!)
My band TRASHVILLE, in which I'm lead guitarist: http://www.youtube.com/watch?v=Z6mU6qaNx08
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#6
Nice to see that somebody gives these questions some thought. I am guilty as anyone of using HDR for *effect* when I first got it - but now very very subtle - that's the secret to making this a real tool in your arsenal and not just another PhotoShop filter.
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#7
To me HDR at the beginning was like a tool to repair what I had done wrong taking my picture. I also used it to the extreme to give that special look HDR images have. There will be times, I am sure, that I will use it, but now with the understanding of what I want to get and to give a special look.

This post made me think about my use of HDR in my photography. Last year I went to the Sea to take a sunset, I had to make an HDR of my image to get detail in the sky. This year, I use my coking filters and the right exposure. My picture didn't need HDR and it is really nice.

Zig,

I am very happy you talk about spot metering here... I've been working a lot in my photography lately, specially in my exposures. It has been always difficult to understand the use of EV... I came across a nice writing about spot metering and exposure compensation and I put it into practice last weekend. It was a sunny day, and we went to the lake. There was a white horse eating in the corral and the forest behind. I took it with spot metering and I metered my light in the grass, no exposure compensation, and the result was fantastic!! My picture was not blown up, plenty of detail in the highlights and the forest was very ok. I had some underexposed areas in the forest but I really don't care, it is not so much and easy to repair in raw.

The other situation was a wooden pole and behind was a bright roof. I used again spot metering and my picture is great. I mean, it is not a wow! picture but in terms of technique I am very pleased.

My only concern about exposing to the right is colors, the more I expose to the right, without blown up anything, the more I lose colors, everything looks washed out. I don't know if I am overdoing my exposure to the right?
A work of art which did not begin in emotion is not art.
Paul Cezanne
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#8
Good discussion, folks! Just to repeat myself, I do like that heavily filtered look when it's used for artistic effect (I'm thinking about some large prints on metallic paper,) but there does seem to be a strong "me too" component to it. Not on this forum, but the fad seems strong still on others, and I suppose I'm noticing it now that I'm trolling the photo sites again. Big Grin

Irma, with regard to what Zig is suggesting, have a look at this (old) article:
http://www.luminous-landscape.com/tutori...ight.shtml

The point the article makes is to expose as far to the right of the histogram as possible without clipping the highlights. That way you retain maximum data.

I posted this one before, but it's an example of how a very high-contrast scene can be controlled with a simple contrast mask to tame the highlights and open up the shadows.
IR + contrast mask (pseudo-HDR Wink ), from 2004:
[Image: 28789238.jpg]
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#9
Thanks so much Mitch for the link of this article in Luminous Landscape. The writing by Ian Lyons was really very useful, specially his explanation and illustration on the compensation curve. I have already tried this with some of my pictures directly in the raw, and works excellent. Colors I never thought I had in my pictures... Wink

Yes I remember well your picture, very beautiful btw. Yes, this is a post processing I have been working on lately. I work in lab color. I make a mask of the luminous chanel, inverse the selecion and work with the rest. The thing I am sometimes not quite happy with is that the selection is a bit too hard and you see when you have worked. I have tried feather the selection a bit and the result comes a bit better.

Thanks again for the link.
A work of art which did not begin in emotion is not art.
Paul Cezanne
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#10
Slej, I hadn't seen that pic before: absolutely breathtaking!! Big Grin
All my stuff is here: www.doverow.com
(Just click on the TOP RIGHT buttons to take you to my Image Galleries or Music Rooms!)
My band TRASHVILLE, in which I'm lead guitarist: http://www.youtube.com/watch?v=Z6mU6qaNx08
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#11
Thanks Zig!
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