Experiments in HDR Photography.

 
I recently added the awesome Photomatix Pro 5 software to my photographic arsenal.
 
Photomatix 'combines' different shots of the same subject to create a single High Dynamic Range image.
 
HDR processing attempts to photographically reproduce the incredible ability of the human eyes/brain to 'see' a vast range of different intensities of light. Although the eyes capture images in much the same way as a camera, the brain is much better at processing the information to produce a correctly 'exposed' image.
 
Unlike our eyesight, film, and latterly digital sensors, can only correctly expose and capture detail within a fairly limited range of different light intensities.
 
For example, if we are looking at someone who is stood with the sun behind them, our eyes and brains are very good at correctly seeing both the bright sky/clouds behind them, and the details of their face and clothes that are in deep shade. Without maybe adding a neutral density filter to darken the sky, or using fill-in flash to brighten the subject, the camera is completely useless at capturing everything in the scene at the correct exposure.
 
If you correctly expose for the person, the likelihood is that the sky behind them will be over-exposed and appear 'blown out'. Conversely, if one exposes correctly for the sky (to preserve detail in the clouds e.g.), the subject will be recorded as a silhouette.
 
Most camera's automatic meters attempt to expose for the 'average' amount of light in the shot (equivalent to a 18% grey tone), so the resultant photograph in the example above will probably be a compromise where there will be a few dim details visible in the subject and the sky will be much too bright, although not completely blown out.
 
HDR photography attempts to solve this problem by merging multiple images of the subject. Each of these images is taken to 'correctly' expose different parts of the image. Most DSLR cameras allow this process to be accomplished automatically with three images, a process called automatic "bracketing". With just a single press of the shutter release, three shots are taken - the first at the 'correct' average exposure, the second is over-exposed by a pre-determined amount, and the third is under-exposed by the same amount.
 
Typically, the difference in exposure can be set to over and under expose up to two "stops"; this refers to the 'f-stop' values inscribed on a camera lens (f2; f4; f8; f16 etc), which control the size of the aperture of the lens diaphragm when the photo is taken. The difference between each f-stop effectively doubles or halves the amount of light that passes through the lens.
 
Although intermediate stops are shown, the relationship runs inversely in the power of 2. For example, a lens set at an aperture of f8 will allow only half the amount of light to pass if set to f4, and twice the amount of light if set to f16.
 
I've been using an automatic bracketing setting of two stops over and under (covering a total range of four stops) so I should theoretically capture detail and correctly expose light intensities that differ by a factor of 16.
 
In addition to merging the exposures of different shots, Photomatix aligns the images, and also has a "de-ghosting" feature which attempts to correct/remove any movement in the shot that may have occurred while the original images were taken. Photomatix offers two settings for these corrections, one for hand-held shots and the other for those taken on a tripod.
 
Anyway, here's a run-through showing how I used Photomatix to create a final merged image from three bracketed exposures.
 
Here are the three images I used for this example:
 
'Correctly' exposed image:
 

 
This image clearly shows the 'compromise' result when using automatic average metering. The sky isn't too bad, although some of it has clipped (blown out). There is some detail visible in the foreground, although overall it's too dark.
 
 
Over-exposed (by 2 stops) image:
 

 
In this image, the foreground is fairly accurately exposed with plenty of detail. The sky, however, is far too bright, lacking in detail except for the darker parts of the cloud, and a lot of it has blown out.
 
 
Under-exposed (by 2 stops) image:
 

 
Here the sky is almost perfectly exposed to reveal a lot of structure and detail, and allowing the richness of the colours to come through. Conversely, the foreground is far too dark and has hardly any discernible detail.
 
 
I open the three images in Photomatix (Load Bracketed Photos) and then select the options for the merge to HDR:
 

 
 
The Deghosting options are shown in the next window that opens:
 
 
 
 
Clicking OK starts the Merge to HDR process.
 
The window that opens contains all the available settings and presets to further process the image (these screenshots are from a different image):
 

 
 
There are two different methods of processing the image:

1. Tone-Mapping (which has three sub-methods):
   
   
2. Exposure Fusion (with 6 sub-methods):
   
   

 
 
Much like a VST plug-in, there are presets, and these can be a good place to start before tweaking the many parameters to get the desired result.
 
Here are the presets, each has a thumbnail to give you an idea of what the process will do to the image:
 





 
 
Finally, once any processing is applied, there are three final 'finishing' touch options available:
 
Contrast:
 

 
 
Colour:
 

 
 
Sharpening:
 

 
 
Here are a couple of slightly different versions of the finished image created from the three original photos:
 

 
 
And slightly more 'garish':
 

 
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Here are a few of my other experiments. I used quite a few different approaches as part of my delving into what Photomatix can do. Some work better than others for sure, but they all do a pretty good job of displaying the full dynamic range of each subject. I've included a montage of the three original images for each one.
 
The final images in each case have been polished up, resized, straightened and cropped if necessary using some combination of Adobe "Photoshop Elements 11", Adobe Lightroom 5, onOne's "Perfect Effects 8" software, and the Viveza 2 & Color Efex Pro 2 modules from Google's Nik Collection effects.
 
 

 

 
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Version 1:

 
Version 2:

 
Version 3:

 
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Cool stuff, btw.

Great stuff, Steve.  Not Bapu is going get it and count it as a plugin. 

Nice work Steve.  I've tried a few of these tools, but tend to either use a graduated ND filter, a fill-in flash for foreground and/or blend the layers by hand if bracketing.  Do you find the auto tools significantly better/quicker?  Where you have a reasonably clear transition point between sky/ground a pre or post filter can work pretty well provided the original exposure is a tad underexposed.

I like both the realistic and the unreal.  Someday I'd like to have a room with a huge lightbox where I can pull down a variety of wonderful scenery (of course, once I'm a multi-millionaire, I'll substitute a 100+" 4Q flatscreen for the lightbox and send images from a PC). 
 
For those old enough (many of us unfortunately  ), it would be like that mural wallpaper from the 70's but with light behind it to make it FAR more realistic.

Hi,
 
I think Photoshop is about to take a hike. Never liked it anyway.
 
This one looks more like a proper tool for a photographer that allows for proper/decent color corrections and trickery that only photographers that do labe work would be aware of.
 
Very nice stuff and yeah ... I have a program that I think I want!

 
I've submitted some of these pics to the Photmatix website, and they said they might display some of them in their gallery
 
I have to say I am rather chuffed

Wood67
Nice work Steve.  I've tried a few of these tools, but tend to either use a graduated ND filter, a fill-in flash for foreground and/or blend the layers by hand if bracketing.  Do you find the auto tools significantly better/quicker?  Where you have a reasonably clear transition point between sky/ground a pre or post filter can work pretty well provided the original exposure is a tad underexposed.

Hi Chris
 
I've often used Cokin ND grads before, but my concern is that using them makes it very difficult to achieve a 'natural' look. Sometimes I reckon you're better off not trying to create a balanced scene, but go all out and use the darkening the sky as an effect for its own sake.
 
Plus if you just want to lower the exposure on the sky, this can be done quickly and with much greater control using software. The graduated filter in Lightroom is really good, and as it's all in the software, you can assign whatever the filter does to variables other than exposure.
 
But although the results are pretty good, especially if you use the Lightroom grad on the first generation RAW to digital negative (DNG) file, I much prefer using HDR to create a level exposure across the image. And taking advantage of the wider exposure latitude of Camera RAW files means you can actually use a single photograph to create an HDR image instead of multiple exposures.
 
By way of a quick example, here's an original RAW (Canon .CR2 file) capture rendered to .jpeg in Lightroom. As I exposed this image for the sky, the foreground is pretty much a silhouette:
 

 
 
Here I processed the image in Lightroom by adding a graduated (exposure) filter to the top bringing the exposure down by around 2½ stops, and then another grad to the bottom adding in an extra 2 stops to bring out the detail:
 

 
 
Using the original (single) RAW image with Photomatix is pretty simple, and works well in Lightroom. I just made two copies of the file and then adjusted the overall exposure of each to mimic the effect of shooting three bracketed shots - I left one as shot, added 2 stops to one and darkened the other by around 2 stops.
 
I then processed the three clones in Photomatix and did a quick fiddle around in Nik Effects:
 

 
All in all, a much more satisfactory result I'd venture.