A Brief HDR Tutorial

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“HDR” stands for High Dynamic Range imaging. The definition from Wikipedia is, “a set of techniques that allow a greater dynamic range of luminances between the lightest and darkest areas of an image than standard digital imaging techniques or photographic methods. This wider dynamic range allows HDR images to more accurately represent the wide range of intensity levels found in real scenes, ranging from direct sunlight to faint starlight.”

It seems to be one of those photography techniques that people either love, or they hate. Like any other technique, the effects of HDR can be used in a subtle way or an overt way. It can be used to give your picture a surreal look, or it can be used to add subtle dimension and contrast. It takes a bit of experimentation and uses both camera techniques and post-processing techniques. Essentially, though, it’s pretty easy to accomplish and modify to suit your own personal needs and tastes.

To achieve the effects of HDR, you will need to shoot in RAW file format.

First, choose your subject and put your camera on a tripod. You’re going to take a series of photographs that need to be composed exactly the same, but will be shot at different exposures. Take the first picture at “normal” exposure, noting the aperture and shutter speed. You’re going to use the exact same aperture for the subsequent shots, but will increase and decrease the shutter speed to over- and under-expose them. This is called “exposure bracketing”, when you “bracket” the normally exposed photograph with one (or more) that is under-exposed and one (or more) that is over-exposed.

Also, be sure to shoot in a low ISO setting to reduce the noise as much as possible, because noise translates very obviously into the final product. I broke that particular rule in the following shots, where I was shooting in the dark outside of my house, at 7:30 at night, using ISO 800. But for the purposes of this short tutorial, I’m sure you get the idea. Ideally I would have taken these photos at ISO 100.

Here is the “normally” exposed shot, 10 seconds at f/13:

10sf13

Here is the “underexposed” shot, 5 seconds at f/13:

5sf13

And here is the “overexposed shot, 20 seconds at f/13:

20sf13

What you’re trying to do is bracket the normally exposed photo with one that is shot at one or two stops up, and one that is shot at one or two stops down. We talked about stops in this entry.

Now we’re going to merge all three photos together. Open all three photographs in Photoshop CS2, CS3, CS4, or Lightroom. Other photo editing software programs will have similar steps to what I describe here.

Go to the “File” menu and choose “Automate”, then “Merge to HDR”. When the “Source Files” screen opens, click the button that says “Add Open Files”. Then click “OK”. Click “OK” again when the program asks you if you want to merge the files to HDR. The next screen offers you a “preview” of the finished file. The files you used to compose the HDR photo are listed to the left, and you can de-select any of the files to remove them from the merge and change the appearance of the final file. You also have the opportunity to adjust the “White Point” by using the white point slider to the right. Moving the slider to the left lightens the appearance, moving it to the right darkens the appearance. The screen opens at a middle setting; for my final shot I set it two-thirds of the way to the right.

Finally, before you click “OK” you’ll want to change the image from 32/bit channel to 8/bit channel, so that you can save the file in JPEG format. If you don’t change it at this point, you can also change the photo’s mode by going to the “Image” menu and selecting “Mode”. If prompted to adjust the “Exposure” and “Gamma”, just leave them at the default setting and click “OK”.

This is the final, merged HDR photo:


As you can see, more detail can be observed in this picture, than what was available in any of the first three pictures that comprised the final HDR photo. The silhouettes of the trees in the back yard are visible, as is a smattering of stars up in the top left hand corner. You can also see how noise really effects the final outcome, so be sure to bump that ISO down!

Personal opinions about the use of the HDR technique aside, you can probably see how this technique would be useful in a variety of circumstances. If you experiement with this technique, we’d love to hear about it! Please feel free to share your experiences and photos in the comments.

Photo credits (all): Tiffany Joyce.

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  • Michael

    Uhmmm… there is something seriously wrong with the final photo. Why is the door massively overexposed, even worse than in the third “overexposed” shot? I don't see more detail here, just the opposite!

    This is definitely not what a properly processed HDR photo should look like. It looks like someone just cranked up the exposure slider on one of the above photos, thereby accentuating chroma noise.

  • Brett

    I agree with Michael, proper HDR processing would have taken the exposure in the door from the underexposed shot, the exposure in the sky from the over exposed shot, and the exposure in the middle areas from the average exposed shot. The final effect (barring a desire for surrealness) would be the ability to see details in brightly lit and low lit areas outside of what would normally be visible with a single exposure shot.

    Also, it is ideal to use RAW for HDRs, but not required. Many HDR-capable software can utilize jpgs for the same effect. Some software can even simulate HDR from a single exposure (RAW or jpg), though the result is limited by what was captured in that exposure.

    As further examples of HDRs, a link to some of mine is below – some more subtle than others. Note that at least the wedding shot was processed using jpgs rather than RAWs. Also, in my opinion, the Castello Sforzesco shot is a good example of capturing different ranges of exposure… from the bright sky to the shadowed wall, HDR processing allowed detail to be pulled from the both extremes which weren't visible in the original RAW files.

    http://www.flickr.com/search/?q=hdr&w=10866280%

  • Brett

    Looks like that link ends up grabbing all HDR shots, not just mine… Let's try this instead.

    http://www.flickr.com/photos/begarner/tags/hdr/

  • http://twitter.com/Snerkology Tiffany

    :D I wasn't going for perfection here, Michael, just demonstration shots to illustrate how to create HDR images.

  • http://twitter.com/Snerkology Tiffany

    HI Brett, thanks for the advice and the examples!

  • http://twitter.com/Snerkology Tiffany

    Also, I see what you mean about the over-exposed door area, but for some reason I wasn't able to correct the exposure of that one area and keep the detail in the others.

  • Anon

    Yeah, sorry I agree with the others- this really isn't an example of HDR- true HDR has more detail than any one of the original images, this clearly has less. I know you weren't going for perfection, but really this isn't HDR at all. I would think that this likely stems from two places- 1 is that while you were using three exposures, the scene really only takes the lit area into consideration. In order for this to work on this scene, your over exposed image would have to be bright enough to correctly expose the grass and other dark areas. It's not as simple as just taking 3 images, you need to make sure that every area in the scene ends up exposed properly in one of the images.
    Second is the use of photoshops HDR- despite it's name, you anyone who works with HDR knows that you can't create a good (even a sample) HDR image right out of photoshops merge to HDR. Photoshop's HDR doesn't offer tone mapping, which is required for HDR on a screen or print (and HDR image has more bits than your computer or a print can view, . tone mapping maps the bits you can't see back into bits you can see- that's a really rough explanation) you need to either use photomatix or some similar program, or maybe with a lot of work you could “fake” the effect in photoshop- I don't know I've not seen that done, I'm just guessing.

    Either way this doesn't work- if you are going for the typical HDR you must be able to tone map the images, if you are going for more of a combined exposure type thing, then you should be able to see ALL of the detail available in any of the original images.

    Either way this Cleary doesn't work, and it goes way behind not just looking for perfection- this isn't even sample worthy.

  • http://twitter.com/Snerkology Tiffany

    Thanks for putting your comments in such a considerate way. I will publish a more technical HDR tutorial in the future but for this one was just going for the brief, simple technique. HDR seems to stir passion in the comments whenever it's mentioned!

  • Andreas

    Thats a very strange final result.

  • nakean

    The range in the last photo is not very dynamic. I would suggest some different tone-mapping. Perhaps a Dark enough exposure was not taken during the original capture of the scene. When shooting you really need to make sure you expose for ALL the detail in both the highlights and the Shadows. Here is a link to my HDR Tutorial…Both video and written blog. There are also 6 RAW files so you can work with the Tutorial. http://www.nakean.com/Nakeans_Photography/Blog/

  • jane

    Nice article. I was very intrigued by the automation aspect of merging the image, as I do this manually in Photoshop and it can be quite a lot of work sometimes. However I wasn't impressed by the final result as the detail in the lighter part of the scene is blown out and the colour seemed to shift quit a bit.

  • Hrm…

    I totally agree with others; that last shot just isn't right. The point of HDR is to capture bracketed exposures to pick up a well-exposed version of everything in your scene, like a shadowy area, a bright sky, etc, that your eye can process into a beautiful scene but your camera has trouble capturing. Only the doorway in your three photos allows you to demonstrate this. The final image just cranks the exposure or brightness. If there is HDR under there, there's no indication. All your processing did was tip so far to the light end of your histogram that you've picked up new details out of the shadows (stars, more foliage) and totally blown out the subject of your shot.

    Check out the work of Trey Radcliff, I think he does it better than anybody else: http://www.flickr.com/stuckincustoms/ .

  • echojeff

    Ditto what Michael said. I have thought a lot of doing this, but wondered how the layers would actually add up in the final picture. Seeing your demonstration confirmed this for me, thanks. There must be something better than this. Maybe a dedicated HDR program would work better. I will see what the others in your comments have done, to learn more. Thanks for your post.

  • bertumayol

    Hello, excuse me, for this comentary, but this photo HDR, very,very bad.
    Very noise, and the door, where is the door ?.
    I'm sorry
    Good bye ¡¡¡¡

  • Photo1017

    Though i cannot understand th purpose in the ‘cheap sci fi film’ look to overone HDR, using HDR to recover shadow detail and broaden the range of an images light is fantastic.
    Though i have to pose the question: why did you do this HDR image in a style that reulted in a blown out door area? Its seems ounter to the intent.