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Icrontic's intro to HDR photography

Icrontic's intro to HDR photography

As far as the photography aspect itself goes, all the exercise requires is an immobile camera and an option to use manual controls on it! Couldn’t be much simpler than that, and that’s likely why we’ve been seeing them crop up all over the place.

The mechanics behind the idea are simple – get a wide range of exposures on your subject of choice, so that all your highlights and shadows in the scene are represented well in at least one of the shots. In other words, make sure you have a good picture of every part of your scene. Taking a wide variety of shots implies two restrictions on us; we want, ideally, to have a static subject (shots of your 5-year-old children are ill-advised), and to get the range we’re looking for, mechanically we want to vary the shutter speed, not the aperture – aperture variations will lead to changes in your depth of field (which parts of the shot are in focus and which aren’t). When we’re trying to build a composite image, we want these shots to ultimately be as completely similar as possible.

How many of these different exposures you want to get is really up to you, balanced between two issues: too few exposures, and you might not catch everything you want, but too many exposures, and they become harder to keep framed exactly the same, potentially introducing blur or general muddiness to the final image. Anywhere between 3 and 7 is usually a good idea, with enough variation over the exposure to make each image distinct from each other. For example, a good small range may look like so:

One other piece of advice here: shoot in RAW if at all possible. This will allow you to modify just about every part of the picture except the focus, and you’ll much more easily be able to make your shot tonality, white balance, color and more match up together.

So you’ve got your shots, now we get to the processing stage. You’ve got to take all the files you’ve got and squeeze them together so they can show off their good parts. Luckily software has evolved that can help us do that, the most popular of which are by far undoubtedly Photomatix and Photoshop CS2 or higher, though free alternatives exist, such as Cinepaint and pfstmo, which run on Linux. Once you’ve taken your photos and saved them somewhere, you can begin working with the software.

If you’re shooting in RAW, Photomatix will almost certainly accept them, as it currently handles Canon, Nikon, Fuji, Olympus, Sony, Pentax, Minolta, Kodak, and Sigma RAW formats; on top of that, it will accept digital negative RAW, Photoshop PSDs, TIFF, Radiance RGBE, OpenEXR, JPEG, and even the Windows BMP bitmaps. As you’d imagine, Photoshop does handle most image types, though I’m unsure if it has the same kind of raw support Photomatix demonstrates; I do know, however, that it can handle Canon RAWs, and will simply convert them to DNG (Photoshop’s digital negative) losslessly upon opening them. When you give these programs your photos, the behind the scenes magic takes them and combines them into one gigantic, chock-full-of-information 32-bit image – that to you, right off the bat, will look totally and utterly revolting. Fear not – our 8-bit displays weren’t built to handle the wonderful 32 bits of goodness we’re trying to throw at it. If you had an HDR monitor, that initial output image would look fantastic.

Since we don’t, we need to press on to another step – tone mapping. As it insinuates, tone mapping is merely the process of mapping colors in relation to each other in order to give the impression of an HDR image – a way to let our monitors fool our eyes and make us think we’re looking at that big 32-bit shot. This is the second time we should be grateful of the advances of modern technology, as tone mapping can be done in about a minute, and results in an image that is orders of magnitude more appealing than the actual HDR file we created not so long ago. I’ll step a little more into the details of the two workflows to try and illustrate their differences.

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Comments

  1. GHoosdum
    GHoosdum I had no idea it was that easy to accomplish!
  2. Kwitko
    Kwitko I love and hate HDR. Sometimes it can be used to achieve great effect, but I've seen some seriously overdone HDR. It seems to work well with landscapes, especially pictures taken at dusk and dawn. Regardless, very nice guide!
  3. UPSLynx
    UPSLynx
    Kwitko wrote:
    I love and hate HDR. Sometimes it can be used to achieve great effect, but I've seen some seriously overdone HDR. It seems to work well with landscapes, especially pictures taken at dusk and dawn. Regardless, very nice guide!


    THIS. I'm the same way, but it's been so overdone as of late, I've just decided to kind of cross my arms and sneer at HDR for the moment.

    DIGG loves HDR, and I see so much over done sub par HDR on there, it kind of burned me out.

    But maybe I'll give it a shot myself. Great guide, very informative.
  4. primesuspect
    primesuspect I think HDR is one of those things you hate until you do one yourself, and then you're like "oh wow, I made that? Awesome!" and you become a fan :D
  5. LIN
    LIN Great tutorial, thanks!
  6. -tk
    -tk Excellent article! This technique is very similiar to doing a pre-exposure with film, and as a recent film to digital convert I've been looking for the digital equivalent. Cheers!

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