HDR / Discussions

Advantages of HDR posted by Doomshammer Posted on Wednesday September 26, 2007 at 14:29. 337 visits. ( permalink )

I already wrote this article in my Ipernity blog, but I like to contribute it to all people in this group. As HDR is the main topic here, it might be interessting for some of you.
(This is of course, just my personal opinion of HDR :-)

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In the comments to this photo, I have been asked by grapf why I've choosen HDR for this shot. As you may notice, it isn't too apparent that this is a HDR composition (compared to other HDR compositions). Well, personally I am not a big fan of these "overrealistic" HDRs - you know.. this kind of HDR where cars look like plastic - but that's just my personal opinion. I rather use HDR to enhance the dynamic range of my photos, so that you can see more details and have better light and stuff. So I try to build my HDRs as realistic as possible.

To give you a brief overview/comparison, I've uploaded the "normal" exposure to the above mentioned HDR composition:



As you can see, the shot isn't to bad at all. But some parts are (at least for my personal taste) too overexposed and the colors are looking a bit flat. Additionally I'd like to have the sky a little more dark red - just to highlight the mood and the daytime. Last but not least, the reflections on the water, are not looking so nice as well. For sure.. I could have done some raw processing to underexpose the photo a bit, but then the roofs and the skyline would fade into dark and details would disappear. As well I could do some image processing with PS to just slightly underexpose some parts of the photo, but this would be lots of work and I doubt that the result would be the same as with the HDR composition.

Now have a look at the HDR version of this shot:



As you will instantly notice, the colors are much more powerful and the reflections are way better than in the above version. The sky now has a really nice mood and shows that the sun was just setting- though the details of the roofs and the skyline are still visible. But besides of this, the most impressive enhancement of the HDR version (at least IMHO) are the colorful lights. They are not as overexposed as in the normal version but though very bright and a real eyecatcher.

So that's my point of view about HDR. I'm curious in hearing your opinions about this post and the comparsion between normal shots and HDR compositions. :-)

8 Replies

M a d . P h o t o . W o r l d pro says: Not to split heads, nor start a war :).... but i think your confusing HDR with LDR :) HDR is about capturing the full luminosity range of a scene. Let me try to explain, what i really mean. Let say you shot the above exposure like this: -4, -2, 0, +2, +4. If you camera can capture 6EV in one exposure, then it will be a total of 12EV, thats a contrast of approx. 4000:1. Paper only shows around 6EV = 100:1 (almost) and so does our monitors (more or less) Now the problem you are facing is getting your HDRI (32bit) down to LDRI (8bit), to be shown on a normal screen. This is now you start to merge, tonemapping and all sorts of funny stuff. I also use the term "HDR" to describe something i have tonemapped, but thats so other people can find them, but they're really not HDR. I think we should all stop calling our tonemapped images HDR until they truly are HDR and until our monitors can really show them. One exception would be if we all start to post openEXR files. They are truly HDRI - OpenEXR can hold 32EV, somewhere close to 4000000000:1 (if my math don't fail me) Very nice colorful light in your picture Posted 4 months ago. ( permalink )

Roberto Ballerini // March'el Ch'est Moa pro replies: Technically you are absolutely correct, but in photosharing sites we are accustomed to call HDR the tonemapping of a HDR... -- Coming from a group home page (?) Posted 4 months ago. ( permalink )

M a d . P h o t o . W o r l d pro says: Unfortunately i have to agree with you. The more people who use HDR as an way of describing a tonemapped HDR, the more people will learn to use it wrong. If we know its wrong, why do we persist in using it? Maybe its about time that we took upon our selfs to change this ? Otherwise in 5-10 years time when we truly have HDRI (and im looking so forward to seeing this), we're really gonna be confused. Whats wrong with calling an image for a tonemapped image ? I doesn't sound as cool as HDRI, but then lets defined a word we can use for it. It could be HDRIT (High Dynamic Range Image ToneMapped), DRIT (Dynamic Range Image ToneMapped) or HRIT (High Range Image ToneMapped), but lets not continue to use HDR. I kind of like HDRIT, you can even pronounce it has H-DRIT :) HDR i also a completely wrong word to use. "High Dynamic Range" of what ? Audio? Video? Image? Posted 4 months ago. ( permalink )

roselover (Sondra) says: Interesting discussion - I now realize what I've been calling HDR is actually tonemapping or HDRIT as the new acronym suggests. One question, can you explain LDR? Posted 3 months ago. ( permalink )

M a d . P h o t o . W o r l d pro says: Great! My idea of the HDRIT was just because i was getting tired of all the confusion. I just called it a tonemapped HDRI, then people know what it is. I think the world has seen enough acronyms :) Simply put. An LDR is any image not capable of showing a High Dynamic Range.... I will bet that the above sentence didn't help, so here i try again. 8bit and 16bit images are all based on whole numbers. A color value will be RGB(23,200,54). The values can be larger if you are working with a bigger bit depth. Like 24bit, at some point your going to clip/destroy your image when you do editing. Try to take an 8bit image and do a drastic contrast curve and watch the histogram. There will (probably) be gaps in it and you can visually see artifacts in your image. Basically your destroying your image or maybe degrading it. Why? Because you can only go from 0-xxx in whole values and at some point your going to run out of numbers. Thats LDR. HDR is all about floating-point. Its a magically space. Its mind blowing. Bet its like going out to space the first time. The color precision in HDR is (by definition) never ending. Colors can be RGB(0.00034, 0.4434434553343, 0.42) or maybe RGB(0.000000000000000000000000000000004, 0.4, 0.222) . Hope it helps - or just ask again :) Posted 2 months ago. ( permalink )

Chris82 pro says: Hmm this is an interesting article although I think I found a very unusual HDR work in your example. Isn't it possible to get such a result by simply tweaking the blacks and contrast of a RAW file without even using Tone Mapping? I see HDR in simple words always as a photo where dark areas are illuminated enough to see all details without overexposing the light areas so you can see the details there as well. In your HDR sample a lot of the details in the dark area is lost in my opinion which can be seen in the original photo while the sky isn't even overexposed there. I had to re-read your lines a few times actually to make sure I am really looking at the HDR right now. Posted 2 months ago. ( permalink )

Roberto Ballerini // March'el Ch'est Moa pro replies: In a real HDR situation it isn't so: the sensor response curves clip values that you can't recover without having more than one exposure; the real problem is that the current Hdr combination and tone mapping algorithm aren't suitable to obtain shot that looks natural... I'm waiting for a standard 32-bit (or more) per channel graphics format: tone mapping is only a way to use a standard JPG format to look at a shot encoded with more than 8 bits per channel, similar to searching a way to put a square peg in a round hole! -- Seen in a group discussion (?) Posted 2 months ago. ( permalink )

M a d . P h o t o . W o r l d pro says: I usually do not process them that much. I like when HDR photography is more "real". Its very seldom that i like the cartoon style. On an occasion i do. To get peoples attention you will succeed more with the cartoon style than the not so obvious ones. Tone mapping is more or less a way of increasing the contrast between two "points", so you can use contrast and tweaking the blacks without ever using a tone mapping plugin. The plugin just makes it easier. I have begun to find tone mapping really boring..sometimes. I usually work directly with the HDR in Photoshop, much more freedom AND it keeps me away from the cartoon style :) Posted 2 months ago. ( permalink )

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