Control on HDR: by chance or by style?

[rhadorn]

I read with much interest the thread about the comparison of various HDR modes (Comparison of Various HDR Modes: Newbie Seeks Advice). To me, this is not at all a newbie question. On the contrary, it expresses a concern with a real understanding of what is going on in the use of the tone mapping programs available. I myself have pushed the sliders around repeatedly and experienced major difficulties in trying to put words on the effect this has on the image. I belong to that group of people, who want to go beyond the gross qualification of the "I like / I don't like" type.

The basic principle of tone mapping HDR shots sounds simple: reduce the overall contrast and enhance the local contrast. But even if one limits oneself to one single program, like Photomatix, the variety of results, which can be obtained, is tremendous. This makes it actually difficult to compare any program with any other: to document the comparison with precision, you should take notice of all values entered and of the position of all sliders.

What we lack is a perceptive / conceptual framework against which we could qualify the visual effects obtained.

The software editors do actually not help us in any way to build such a framework. The explanation about what the program does behind the scenes is quasi inexistent. I expected some help of several books I bought or went through, but most of the time, the authors copy/paste the tutorial of the program and conclude writing "try yourself", which at the end means "help yourself"... This is not a fifty bucks worth.


Tone mapping works best when there is a clear delimitation between large scale zones with clearly distinct groups of tones; The image of Westminster discussed in the cited thread complies largely with this requisite. I yet agree with the contributor, who suggested that the picture would eventually be best rendered by an appropriate edition of a single shot.

Tone mapping works much less well when the tones from the whole 14 EV DR mix up on a small scale, which will be the case for an image taken in a forest with very large tonal differences between bright rocks in the sun and wet woods in the shadow.

The worst thing, which may happen, is an inversion of tonal values, where the brightest point in the original picture turns gray, sometimes a fairly pronounced Grey, just because it is large enough to be treated by the program as a bright gross zone, which has to be mapped down. In some programs, the radius of the details, which have to be enhanced on the local level, is user defined. On the opposite, the scale of the gross zones, to be compressed, is out of the reach of the user. And in any case, a real image involves usually zones of various scales, a variety which is not best handled by software, which will apply a uniform filter for defining the picture zones.

So, we get artifacts not only due to the detail enhancing technique used (the halos) but also due to a mismatch between the presuppositions the algorithm works with and the scale of the gross zones and smaller details in the picture.

In my view, the gross zones to be globally remapped should be user defined, by the way of a selection operator (the spline curves of Lightzone would be perfect for that), because the user only knows which mapping really makes sense. The 'universally applicable' technical criteria predefined in the software MUST mismatch with a majority of pictures. A software cannot Analise a picture as does the human eye 'n brain.


Presently, I try to build a two stage process in which I have more control. In a first stage, I compress the overall range to fit most of it into a tiff file. In a second stage, I use a picture editing program to enhance local detail at various radii and on selected parts of the picture. The main difficulty is to find a program, which really just compresses the overall range without adding local contrast by itself. As I discovered HDR Exposure, I first believed it made this possible; experimenting more, it appeared that all tone mapping procedures it proposes include local contrast enhancement, which produces the unwanted tone scale inversions in the highlights.

At the moment, I feel that the Compression tab in Photomatix is the best option, because it preserves the high value of the highlights although it seems to apply local contrast in the mid tones and shadows (Contrast Adaptation). Of course, if some of you have made better experiences with other programs, I would be happy to read about it.


As of HDR in itself, I wonder if the scope of the processing is not somehow ill-defined. Of course, the luminosity may span over 16 to 24 EV's in some scenes and thanks to its multiple adaptive mechanisms (physical, physiological and neural), the human vision can capture the whole span with detail, provided one gives it the time to adapt to specific viewing conditions. Even the human eye cannot differentiate bright colors in the sun and subtle shades in a deep shade AT THE SAME TIME. In reality, for given viewing conditions, it may well be that the effective dynamic range covered at a glance goes not beyond 8 to 12 EVs... This may be a reason why images covering about that range feel realistic, on screen as on print.

I tried to experiment this the other day while hiking in a bright rocky landscape with many shades from very bright to deep shadows. Looking in various directions and concentrating either on bright sunlit stones or on dark pieces of wood in the shadows, I certainly covered a wide range, say 16 EV. But obviously, I did not see any detail in shades while concentrating on bright rocks and the latter were totally 'overexposed' while I concentrated on shades. So, human vision itself seems not to cover the same range if one considers panning around, giving the adaptive mechanisms time to adapt, or a snapshot, where human vision seems to be far more limited.

If the description above fits, then HDR tone mapping consists in squeezing the panning view over time into a snapshot view. It makes it possible to see in a snapshot 'as much' as panning around. It is a play with various kinds of visions rather than an extension of the photographic capabilities to the capabilities of human vision.


To me, this means that straight pictures limited to 8-12 EV's should not only be viewed as a result of technical limitations of the screen and print but also as the most 'truthful' reproduction of a snapshot a human being takes of a situation. On the other hand, tone mapped pictures squeezing overall contrast into those 8-12 EV's and blowing up local contrast feel more artificial, because we never really see things like this. This does not mean that they should not be made. To me, they have a status similar to the views astronomers take of distant galaxies in false colors: the manipulation is aimed at making something visible, which otherwise would be overseen. The question which we have to answer as photographers concerns the sense of the manipulation. One can consider documentation, stylistic, artistic aspects. Here I come back to the discussion launched by John T. in the other thread: how far is the HDR to 'grunge style' merely a consequence of the technique applied, to what extension is it a choice which makes it the signature of an artist?

There is nothing like 'photorealism'. Photographic pictures are always transposition. Solarisation, toning, contrast enhancing, low or high key, blurring, exaggerated grain, many manipulations have been used with best results. HDR tone mapping can also produce 'artistic' results (whatever this means...). My feeling is yet that many tone mapped pictures are obtained more or less 'by chance' and that the technical constraints of the programs presently available are raised to the status of 'style'. There is still much to be done to have real control on a high dynamic range.

Reto

[Colin Southern]

Hi Reto,

2 things come to my mind ...

1. My observation is that in many examples I've seen, HDR images are very much "out of control" - typically grossly over-saturated.

2. In my opinion, Photomatix is so dangerous it almost needs a licence to be allowed to use it (I think it kills more images than hand guns kill people).

[Colin Southern]

Hi Reto,

2 things come to my mind ...

1. My observation is that in many examples I've seen, HDR images are very much "out of control" - typically grossly over-saturated.

2. In my opinion, Photomatix is so dangerous it almost needs a licence to be allowed to use it (I think it kills more images than hand guns kill people).

How'd I do? (mostly done by mal-manipulating ACR sliders) (vibrance & clarity maxed out, blacks and fill light pushed, and then grossly over-sharpened).

[Edwin Harvey]

Brilliant Colin & in my mind not overdone. Photomatix is a great piece of software, which I most always use to edit my AEB images.
Cheers......Edwin.

[Colin Southern]

Brilliant Colin & in my mind not overdone. Photomatix is a great piece of software, which I most always use to edit my AEB images.
Cheers......Edwin.

Hi Edwin,

To be honest with you, approx 100% of the images I see produced with Photomatix need to be processed in Photoshop afterwards (but aren't) -- and just end up looking grossly "over-processed"

[rhadorn]

I am happy that I am not in charge of saying what is good and what is bad, over or under. Nor that a landscape is bad BECAUSE it has been taken at noon. New artistic trends rarely develop as the expression of a norm...

My expectation is just to find a software, which gives me more room to decide myself how the mapping has to be done. In most present software, the user can only tune a pre-mapped picture, instead of being responsible for the whole mapping. This is also true for Photomatix, even if I recon that the staightest tonemapping procedure I know is Compression in Photomatix.

Reto

[mastamak]

Hi Edwin,

To be honest with you, approx 100% of the images I see produced with Photomatix need to be processed in Photoshop afterwards (but aren't) -- and just end up looking grossly "over-processed"

I agree with you, Colin, but overprocessing is not limited to HDR software. I think most people can pick an image that has been overcooked in Photoshop or Lightroom. I guess this brings us back to the argument of how much processing is too much. Is it legitimate to process an image to the point where it no longer resembles the scene captured on the day? Or should you try to limit post-processing to achieving a more accurate or enhanced representation of what you actually saw. Then of course, one can argue that there is a legitimate role for more extensive post-processing so that the viewer not only appreciates the scene captured but gains a feel for the atmosphere of the location and circumstances under which the image was captured. At what point in the process does an image change from being a photographic representation of a landscape, for example, to some other new art form with no pretension of representing the original scene.

When I see a great landscape photograph my immediate reaction is that I would like to visit that place and experience that landscape, myself. I guess I feel somewhat cheated, however, when I see an image that gives an entirely unrealistic impression. (Never on this forum, I hasten to add )

I also agree with Reto's comments on Photomatix. From my limited experience you can achieve some very attractive results but is a hit and miss affair. It is a matter of jiggling the sliders, holding your tongue in exactly the right position, crossing your fingers and then, just maybe, all will be well. It is near impossible to work out what is going on and you have no real idea of what the final product will look like until it is processed and printed.

Grant

[Colin Southern]

I agree with you, Colin, but overprocessing is not limited to HDR software.

Hi Grant,

I know what you mean - it just seems to be that 99% of the grossly over-processed image that I see seem to arrive via Photomatix. I suspect that when one grossly over-cooks something with Photoshop it's often called "grossly over-cooked", but when someone ends up with a hidiously over-processed image produced with Photomatix, there's a tendency to call it "HDR" rather than "surreal" or even "art".

It even comes in at #5 on the Photo Editing Offences list!

http://www.flickr.com/groups/peo/

[Blazing fire]

I guess this brings us back to the argument of how much processing is too much. Is it legitimate to process an image to the point where it no longer resembles the scene captured on the day? Or should you try to limit post-processing to achieving a more accurate or enhanced representation of what you actually saw. Then of course, one can argue that there is a legitimate role for more extensive post-processing so that the viewer not only appreciates the scene captured but gains a feel for the atmosphere of the location and circumstances under which the image was captured. At what point in the process does an image change from being a photographic representation of a landscape, for example, to some other new art form with no pretension of representing the original scene.

Cheers for the excellent write up!
Photography is afterall, subjective, so we can't please everyone. But we should do whatever pleases us.

[Shadowman]

A combined effort. Shooting in low light conditions, using manual focus, and using HDR conversion. I used FDRTools for the HDR, Nikon D60, 50mm f/1.8mm lens, manual focus, post processing with photoshop elements 8.

[arith]

I thought I might give Photomatix a try to see for myself how hard it is to be realistic. Well it certainly has a lot of sliders with meaningless labels and I found it impossible to get a realistic image. I had to use something to reduce red after processing this as well as increase brightness.

[Colin Southern]

I thought I might give Photomatix a try to see for myself how hard it is to be realistic. Well it certainly has a lot of sliders with meaningless labels and I found it impossible to get a realistic image. I had to use something to reduce red after processing this as well as increase brightness.

Hi Steve,

The irony of it all is that when I last checked their website they had quite a few links to users galleries and ALL the ones I checked had very nice PHOTOREALISTIC images - not an over-cooked image in site!

[arith]

They must be cheatin then Colin, maybe they don't count photoshop as PP.

[Colin Southern]

They must be cheatin then Colin, maybe they don't count photoshop as PP.

I think a lot of HDR shooters fail to realize that HDR software only gets one in the ballpark - from there one HAS to finish the job using conventional techniques.

[delboy]

Hi Edwin,

To be honest with you, approx 100% of the images I see produced with Photomatix need to be processed in Photoshop afterwards (but aren't) -- and just end up looking grossly "over-processed"

Well said Colin

I have tried the trail version of Photomatix My first reaction was "yuk" the colours were so false it felt like eating a sickly sweet cake. I then opened up the image in Adobe raw and adjusted the sliders until I got a image I thought was reasonable. Got a reasonable result even though it lacks a bit of contrast. Can see the use of this programme in situations like this were the interior needs to be correctly exposed without over exposing the outside detail. See photo attached.


Delboy

[Colin Southern]

Well said Colin

I have tried the the trail version of Photomatix My first reaction was "uyk" the colours were so false it felt like eating a sickly sweet cake. I then opened up the image in Adobe raw and adjusted the sliders until I got a image I thought was reasonable. Got a reasonable result even though it lacks a bit of contrast. Can see the use of this programme in situations like this were the interior needs to be correctly exposed without over exposing the outside detail. See photo attached.

Delboy

Interestingly, I watched a video on HDR (including Photomatix) a few days ago -- and I'm starting to wonder if the typical "photomatixed" image that we're seeing is just the users getting a bit (ok, a LOT) ham-fisted with the controls. I've downloaded the latest version ... might have to have more of a play with it, although to be honest, ACR's fill light normally works like a treat to me; true, local contrast can be a bit of an issue, but that's what "hand massaging data" is all about

[timo2]

I have tried the the trail version of Photomatix My first reaction was "uyk" the colours were so false it felt like eating a sickly sweet cake.

Photomatix has sliders for Temperature and Saturation for both Highlights and Shadows so the colour setting is up to the user.

[Colin Southern]

Photomatix has sliders for Temperature and Saturation for both Highlights and Shadows so the colour setting is up to the user.

Hi Tim,

I suspect that delboy was referring more to the over-saturation & over-sharpening that produces the "notorious" surreal effect associated with many Photomatix images.

[delboy]

Hi Tim,

I suspect that delboy was referring more to the over-saturation & over-sharpening that produces the "notorious" surreal effect associated with many Photomatix images.

That is correct Colin, I guess I should have made my post a bit clearer. I have had a go at your idea of using the fill slider, impressed with the result.

Delboy

[Colin Southern]

That is correct Colin, I guess I should have made my post a bit clearer. I have had a go at your idea of using the fill slider, impressed with the result.

Delboy

Yes - It's quite amazing how much info is actually tucked away in those shadow areas.

PS: I keep forgetting to ask ... what's your first name?