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Xenedis
25-05-2011, 5:36pm
I've just posted on my blog some of my thoughts on HDR imaging, as well as my techniques and some general advice.

I figured I'd re-post it here. Hopefully it will be of benefit to those interested in HDR imaging.


Some Thoughts on HDR Imaging


The concept of HDR (high dynamic range) imaging is something that either elicits glee or horror.

Over the last few years, thanks to software such as Photomatix Pro, it has been possible to automatically produce composite images using bracketed exposures in order to bring out rich detail which is impossible for a camera to capture in a single frame.

It has been done with varying levels of success.

Unfortunately, many who have dabbled with HDR imaging have produced horribly over-processed, garish images which have unnaturally saturated (almost radioactive) colours, higher-than-acceptable levels of noise, halos around tonally contrasty areas, and an altogether illustrated look which depletes the subject matter of any photo-realism.

The sorts of grossly over-cooked HDR images on the Internet has led some people to believe or state that HDR is an abbreviation for 'Hardly Done Right'. And they'd be correct.

Early this year I began experimenting with HDR imaging. Looking back at the 23 images I have shot and published so far this year, 15 of them have been HDR images. That's two thirds of my 2011-shot images thus far.

When I started, I aimed specifically to avoid producing the cringe-worthy over-cooked images so prolific on the Internet. I wanted to use HDR imaging techniques to bring out, in a natural way, the details our eyes can see. I wanted to depict reality, not fantasy.

I think I have achieved that, and avoided what some call the 'Photomatix look'. Anyone who knows the dynamic range limitations of a camera operating in a high-contrast scene will realise that my images are HDR images, but hopefully, those who don't know much about cameras and to whom the letters H, D and R are random letters of the alphabet, won't realise that my HDR images are HDR images. The idea is that my images should look like what one would expect to see if one were at the scene at the time of capture.

What I find difficult to understand is how, using Photomatix, people can over-cook images in such a ghastly manner. Photomatix has some presets, two of which I consider way over the top; but using some of the more subdued presets, it is possible to produce photo-realistic images without really doing much work.

My first HDR image (http://www.xenedis.net/viewimage.php?i=5365151573) was a Photomatix-merged composite of seven images I had shot within the -3EV to +3EV range. What Photomatix produced was very photo-realistic, albeit flat in tone. I didn't need to tweak any sliders or fiddle with any settings to produce something realistic and pleasing.

I have found that HDR processing tends to suck the black tones out of an image, so it's necessary in post-processing to boost the blacks and mid-tones so the image doesn't look so flat.

Depending on the subject matter, with Photomatix, it requires some conscious and deliberate effort to produce a ghastly HDR image. It's astonishingly easy to produce a realistic image without going to any trouble.

HDR imaging can produce spectacular, photo-realistic results; but my view is that, like any post-processing, less is more; and that one must at all costs avoid clicking the 'Process the Hell Out Of This' button, and exercise restraint.

These days when I shoot, I shoot with HDR imaging in mind, and my technique begins at the capture phase.

I firstly use a solid, rock-steady tripod to ensure consistent framing in each bracketed image. I then capture a series of images of the same scene with the exact same framing, a stop apart. Depending on the available light at the scene, I will bracket five or seven images. More contrast-laden scenes require more images to capture the entire gamut of tonality, whereas less contrast-laden scenes will not require as many exposure values.

Naturally, I shoot in raw mode so that my source images are as unprocessed as possible, have no white balance settings locked in, and don't sacrifice details by dropping the bit depth and applying compression, as is the case with JPG mode.

Back in the digital darkroom, I apply consistent raw conversion to all of my images, whereby I set the white balance, apply raw pre-sharpening, choose a white balance either from a preset or a custom value in degrees Kelvin, boost the clarity and maybe occasionally boost the vibrance or black tones.

Once I've dropped my series of bracketed images into Photoshop, I drop the bit depth to 8-bit and save them all as JPGs using the highest quality value (12).

I then drag the JPGs into Photomatix and at the tone mapping phase select the 'Fusion - Default' preset. This is a fairly neutral preset that produces realistic results.

Once I have my tone-mapped TIFF image, I open it in Photoshop and apply my normal post-processing workflow (which can and does vary from image to image).

One of the first things to be done with a newly-generated HDR image is to apply a levels adjustment layer and increase the blacks (drag the left-most slider more to the right) and adjust the mid-tones by dragging the middle slider. The image will inherently gain more contrast and tonality with that simple step. Then it's a matter of applying whatever other processing one would normally apply.

The key to successful and realistic HDR imaging is not to overdo it. Too much contrast or too much colour, which can be the result of an aggressive tone mapping preset, can result in garish images which have the 'Photomatix look'. Saturation and contrast can be easily and subtly added in post-processing, but if the HDR-merged image has too much saturation or contrast from the beginning, it looks dreadful and takes more work to remove (assuming it's even possible to restore reality to the image).

I have barely six months of experience with HDR, but I am fortunate in that I've found a way, with little effort, to produce realistic, pleasing images that avoid the pitfalls across which so many have stumbled.

Less is more, and more is less.

peterb666
25-05-2011, 7:42pm
Great write up there Xenedis. You have certainly nailed it on "The key to successful and realistic HDR imaging is not to overdo it". I love your HDR work. They have been fab from day 1.

I agree with the general observation that HDR often sucks out the blacks.

One point, I never use JPEGs, not even uncompressed JPEGs due to 8-bit colour limitation. I only use uncompressed TIFFs as intermediaries. My earlier stuff converting from RAW was a disaster in Photomatix however now that I know more about how I like my colour balance under different lighting conditions, I am increasing using RAW wherever possible. It removes one layer in the processing and if you are not getting it right in the JPEG/TIFF generation, only making things a little more difficult.

I quite like desaturated images and I quite often desaturate my images slightly after generating the HDR. This doesn't seem to sit well with people who love their 'Kodak' colour or 'Canon' colour but everyone has different tastes. Then again, I quite often compromise to appease the demand for saturated images and to keep the masses happy.

:th3::th3::th3:

Xenedis
25-05-2011, 8:15pm
Great write up there Xenedis. You have certainly nailed it on "The key to successful and realistic HDR imaging is not to overdo it". I love your HDR work. They have been fab from day 1.

Wow Peter -- that is a big compliment. Thanks muchly.


I agree with the general observation that HDR often sucks out the blacks.

When I was looking into HDR in the beginning, a tutorial I read explained that the blacks tend to get lost, and its author advised the use of the levels adjustment layer.

I hadn't used the levels tool for a long time prior, but I've found it can be very useful, and that indeed, the blacks and mids do take a hit as a result of HDR processing. In my QVB interior shots, there was very little post-processing. From memory, one or two of those images had only a levels adjustment layer and a final layer for sharpening.


One point, I never use JPEGs, not even uncompressed JPEGs due to 8-bit colour limitation. I only use uncompressed TIFFs as intermediaries. My earlier stuff converting from RAW was a disaster in Photomatix however now that I know more about how I like my colour balance under different lighting conditions, I am increasing using RAW wherever possible. It removes one layer in the processing and if you are not getting it right in the JPEG/TIFF generation, only making things a little more difficult.

I ordinarily wouldn't use JPGs either, but one of the tutorials I read strongly recommended it. In all honesty, I cannot remember the reason, but it does seem to produce better results.

Even with one of my recent White Bay images, I saw different results when processing the raw images. I'd have to experiment and see the visual difference between my JPGs, which result from my raw conversion and pre-processing; and the raw images with whatever raw conversion Photomatix applies.



I quite like desaturated images and I quite often desaturate my images slightly after generating the HDR.

In some cases it is necessary, as the colour seemingly gets abnormally boosted during HDR processing.

HDR aside, selective desaturation can be a very effective method of drawing attention to key subject matter. I don't use it often, but have used it within a few images.


This doesn't seem to sit well with people who love their 'Kodak' colour or 'Canon' colour but everyone has different tastes. Then again, I quite often compromise to appease the demand for saturated images and to keep the masses happy.

I seldom compromise.

I tend to be a lot more liberal with colour, and don't even bother with colour correction. I go by what my eyes like, but if an image is too saturated, I'll tend to lower the intensity somewhat.

Dylan & Marianne
26-05-2011, 3:39pm
great write up - I couldn't agree more :)
If I sit back and look at my own HDR images and I think to myself that it looks 'photomatix-ish' , it's back to the drawing board.
I think the other key to your success is that you've always shot well withoutHDR and hence applied the same techniques into the HDR process.
Many people these days try to put the horse before the cart and shoot with HDR in mind without getting other fundamentals of composition / exposure etc correct ; so much so that the emphasis on HDR gets in the way of improvement in those other more important areas.

Keith Young
26-05-2011, 3:57pm
While you are at it, google "Oloneo Photo Engine" its another new kid on the block for HDR but I have been using its Beta version for almost 12 months now and its results are very pleasing. It will even HDR straight off the RAW file with better results than PM Raw. Of course it also takes 8 and 16bit tiffs and jpgs. It only has a month left before it goes to full release, but if you sign up now they will give all beta users a discount on the release (although the proposed release price I think is a bit steep!) hey its still free for a month so you may as well give it a go. I'm thinking they will be forced to reduce the price further because of the huge share of the market PM has. But until then I too will have to go back to using my copy of PM until OPE is around the $50 mark.

Xenedis
26-05-2011, 4:19pm
great write up - I couldn't agree more :)

Cheers. :-)


I think the other key to your success is that you've always shot well withoutHDR and hence applied the same techniques into the HDR process.

A very nice compliment indeed!


Many people these days try to put the horse before the cart and shoot with HDR in mind without getting other fundamentals of composition / exposure etc correct ; so much so that the emphasis on HDR gets in the way of improvement in those other more important areas.

I think you've made a very important point there.

HDR isn't a silver bullet to improve an inherently bad image. It's still important to use correct technique at the capture phase, with composition, exposure, depth of field and focus in mind.

Like general post-processing, HDR won't turn a dreadful image into a work of art; it will just turn a dreadful image into a horribly over-processed, dreadful image.

Effects are best use sparingly and with restraint; the idea of HDR and other PP techniques -- in my mind at least -- is to enhance a good image, not to over-compensate for a bad image or to be about the processing itself.

Geoff79
27-05-2011, 2:10pm
Great write-up, mate. All this sort of stuff I find very helpful. :)

So is putting RAW images straight into Photomatix pretty much a completely dreadful idea?

If you're instead using JPEG or TIFF images after RAW conversion, is it critical to make sure tweaks such as sharpening is identical across all photos being used to create the single HDR image?

Xenedis
29-05-2011, 7:34am
Thanks Geoff.

To be honest, I'd need to perform the same HDR processing twice to see what results Photomatix produces:

1. using a series of untouched raw images; and
2. using the same images after I have applied my standard raw conversion and produced high-quality JPGs.

I might do this later today and post the results without applying any other post-processing.

Xenedis
29-05-2011, 3:33pm
I'd need to perform the same HDR processing twice to see what results Photomatix produces:

1. using a series of untouched raw images; and
2. using the same images after I have applied my standard raw conversion and produced high-quality JPGs.

I might do this later today and post the results without applying any other post-processing.

I mentioned in my opening post in this thread that I produce my HDR images in Photomatix Pro by merging and tone mapping high-quality JPGs which I have produced by first converting my raw images in Adobe Camera Raw.

Peter said he only produces his HDR images from raw files, and Geoff was curious as to whether doing so was a bad idea.

I decided to act upon my musing above and perform an experiment to compare the JPG method I endorse against the raw method.

Using Photomatix Pro, I produced two HDR images.

Five images (shot a stop apart, with identical framing, aperture and ISO) were merged with Photomatix Pro, and tone mapped using the 'Fusion - Default' preset. Other than resizing and saving in JPG format, I have performed no post-processing to the images Photomatix produced.

On the first run, I used high-quality JPGs, which I had produced from raw images. I applied the following settings in Adobe Camera Raw:


Camera Profile: Camera Standard
Sharpening Amount: 50
White Balance: Auto
Temperature: 5250
Clarity: +30

Here is the result:

http://farm3.static.flickr.com/2116/5770095047_41475523e7_b_d.jpg


On the second run, I use unprocessed Canon raw files. In Photomatix Pro, I used the following raw conversion settings (there are no other options for raw conversion):


White Balance: Auto
Color primaries HDR based on: sRGB

Here is the result:

http://farm3.static.flickr.com/2685/5770634350_dbbdef053f_b_d.jpg


And lastly, here is my final, published image, the HDR image of which was produced using high-quality JPGs, and to which I afterwards applied my own post-processing in Photoshop.

http://farm6.static.flickr.com/5029/5744791461_b2f49d11a3_b_d.jpg (http://www.flickr.com/photos/xenedis/5744791461/)


Based on the results above, my advice is to perform raw conversion first and work from JPGs rather than feeding raw images straight into Photomatix Pro. In my experience, Adobe Camera Raw does a much better job, and Photomatix Pro produces a clearly superior result when it is fed high-quality JPG images.

bobt
29-05-2011, 5:45pm
Thanks for going to the trouble of writing this .... it's exactly why I come to on-line camera groups - to seek and share knowledge, and without people prepared to contribute in this way we would all be the poorer. HDR is an interesting - in fact fascinating aspect of photography, and one which everyone should try at some point. I like both the extreme and the conservative looks, each has their place in my view - but that's one of the beauties of photography - we can all see different interpretations of much the same scene. Excellent article! :)

Xenedis
29-05-2011, 5:59pm
Thanks muchly, Bob.

I'm glad you found some value in my article.

HDR is certainly an interesting development in photography, and it does allow for possibilities a camera alone cannot achieve.

ricstew
29-05-2011, 7:24pm
I have been going from LR to Photomatix Pro. Right click and send as tiffs.......I will have to try jpgs I see........I am another that likes both forms of HDR but I have a long way to go yet. This might give you a giggle but don't click if you don't like SWEARING http://ihateyourhdr.tumblr.com/

cheers
Jan

Xenedis
29-05-2011, 7:49pm
This might give you a giggle but don't click if you don't like SWEARING http://ihateyourhdr.tumblr.com/

Indeed it did. There were some hideous images on that site, but the comments were amusing.