HDR Tutorial

Introduction

Since some people have asked me how I take and make my images, this tutorial is will show you the steps that I follow when creating my images. There are many different methods and pieces of software out there to produce HDR images, but this is the way I do it. I’m constantly improving my techniques and I’ll update this tutorial from time to time.
This tutorial is provided completely free of charge, with no guarantee that it will help you take great shots, but I do hope it encourages you to explore HDR. You too can create HDR images!

What is HDR?

High Dynamic Range (HDR) images are simply images that capture the differences between the luminance of the darkest and lightest shades of a scene. The human eye can perceive a vast dynamic range. Just take a look outside on a sunny day and see how you can see the brightest points and still see the dark shadows. Although they are improving all the time, digital camera sensors cannot currently come anywhere close to matching the range that the human eye can see.

When taking some shots your camera is not capable of capturing both ends of the dynamic range. This then is where HDR comes in. An HDR image is created from a number of different exposures of the same shot. This can be anywhere from 3 (-2, 0 +2) to 9 (-4,-3,-2,-1,0,+1,+2,+3,+4) exposures, it does depend on your camera as to how many shot you will be able to take. Look up auto-bracketing in your camera’s manual to find out how to set up your camera.

Although the usual method for HDR uses multiple images at different exposures, you can create an HDR from a single raw image, it is something that I rarely do, only when there it too much movement to capture 3 exposures, but it does follow the same method detailed below.

What do you need

OK, so first things first, you need a few things to be able to produce these images:

  • A digital camera capable of auto-bracketing (required).
  • A sturdy tripod (required). It’s not impossible to take multiple exposed shots hand held without moving the camera, but a tripod sure helps and I’d recommend one.
  • HDR software (required). I’ll be concentrating on my preferred choice, Photomatix Pro
  • Photoshop (required). The buck doesn’t stop with producing the HDR image; there is more processing afterwards.
  • Noise reduction plugin for Photoshop (optional but recommended). I use Noise Ninja but there are plenty of others available.

You can download a free trial version of photomatix from their website.

Note, throughout this tutorial, clicking on the images will take to flickr where you can view the images in full size.

Step 1 – Take your shots

Right that’s the equipment sorted, now let’s get down to the nitty gritty.

Once you’ve found your scene you need to take your shots. I usually set up my Canon to take 3 shots, auto-bracketing to -2, 0, +2. I find that in most situations 3 shots at a step of +/-2 are sufficient. Occasionally I may go for -2,-1,0,+1,+2 and use all 5 shots but very rarely. (plus with my Canon it does require a bit of tweaking mid-shot that risks moving the camera).

One other thing, shoot your images in RAW. Yes, you can produce HDR images from Jpeg but the RAW format will give you greater flexibility later as we do some post-processing.

For this tutorial I’m going to use one of my church interior shots. This gives a good example of what I mean by extremes of light level. Church’s are often wonderfully medieval or gothic in design, with the interior lighting usually relatively poor at lighting up the whole room. There is often a massive range between the lightest point and the darkest point in the scene.

before_after

In the above image you a can see the original normally exposed shot on the left. It’s a pretty dark and unimpressive picture. You don’t get the feeling of grandeur and opulence that a lot of UK churches have. The altar is dull and dark, the colours are dull and the stained windows are blown out. Compare it to the right and part of the image and it’s a whole different ball game. This then shows the difference of what HDR can make.

Ignore the fact that the image is not level. We’ll fix that later in Photoshop along with a few other things.

Step 2 – Produce the HDR

First I convert the RAW files to Jpeg’s, Photomatix can actually convert the RAW files itself, but even the guys at HDRsoft fully admit that their converter is not a patch on a proper RAW converter. I use Adobe Camera RAW to open up each image and save them as Jpeg, I do virtually nothing else to the image at this stage.

Right, let’s fire up Photomatix and get it going on our image.

In this step we will take our 3 (or more) Jpegs and let Photomatix produce an HDR image. Then we will use the tone mapping options to adjust the image to our liking.

There are a number of ways to start the HDR process, but my usual method is to grab the three images in Adobe Bridge and drop them in to the Photomatix window. You’ll then see the following screen

screen2

Select the “Generate HDR” option and click the “OK” button. The next set of options is displayed.

screen3

Nothing to do here, just press “OK”.

screen4

Now we are presented with a few options about the images being imported and how you what to handle them.

Align images is the only option here that I will usually turn on. I normally shoot with a tripod and a remote shutter release so camera shake is minimal, if at all so it’s not really needed, but I usually leave this turned on with “match features” selected

I don’t worry about the other options here, I use Photoshop to sort out and issues with noise, ghosting and chromatic aberrations afterwards. But feel free to experiment with them if you like. You can’t make any mistakes with these options.

Hit “OK” and your computer with go to work generating the HDR image. This will take a few minutes, depending on your computer and the size of your images.

When it’s done you’ll see a very dark looking image on the screen.

Untitled-2

Don’t worry, we’re nowhere near finished yet, this is the actuall 32-bit HDR image. There are no monitors capable of displaying these images correctly yet so it looks kind of funny. Now we have to do it to Tone-map the image to make it viewable.

Once you’ve finished looking at the weird dark HDR image, go ahead and click the “tone mapping” button.

Aha that’s better! You will now get a nicer looking image with a whole manner of sliders and options on the left hand side. These are what we will use to make the final image. These options allow you to create everything from a subtle HDR image to a glow-in-the-dark-Andy-Warhol-look-a-like image and pretty much everything in between. I’m not a fan of the over-processed look, but I know there are people out there who are. (I’m seen some of them on flickr, but I try to stay away as they hurts my eyes).

There are no set in stone things that I do here, although I do have a standard jumping off point saved as a preset. Below is an example of the options I choose initially as a guide. Experiment see what you like best and what works best for you.

Untitled-3

  • Strength – I tend to keep this pretty high, normally about the 80-90 mark but I have been known to go to 100 and down below 50.

  • Colour Saturation – Please don’t overdo it. Don’t make if so high that it produces a colour that makes your eyes water. I tend to stick with somewhere between 20-40 again depending on the image. Anything higher and you’re getting in to Andy Warhol territory again.
  • Luminosity – The further to the right you move this, the less contrast there will be in the photo. If you find yourself with the dreaded “Halo” effect in daylight shots, moving this to the far right will help.
  • Micro contrast – This slider helps the details and fluctuations in colours on the very small scale. Like the others, play with this until it looks and feels right.
  • Light Smoothing – This option affects the “edges” in your image. a bit like the “find edges” in Photoshop. I tend to stick with the second from the right. Go left and you are calling Mr Warhol again.
  • White Point & Black Point – Adjust these two sliders so that the bell of the histogram falls within the graph. If it tails of the side you are losing details of the image.
  • All the other sliders? They are interesting, but I honestly don’t use them much.

Play around with all the sliders and see what works for you. Once you are happy with the preview of your image, hit the “process” button to produce your HDR image and save it out. It is worth noting that the preview is not exactly the same as your final tone mapped image will turn out. It is estimation and more often than not the image will be slightly darker than the preview. At this stage I save my images as 8-bit Tiff, Tiff is a lossless format and so stores more data that a Jpeg.

almost

Step 3 – Photoshop

OK so that’s half the work done, we’ve taken the shot and produced the initial HDR image. It looks nice, but it’s no way near finished yet. We need Photoshop to help us out with a few things.

  • Repairing the ghosting or people and objects
  • repair the blown out areas of the photo
  • Fix Chromatic Aberrations
  • Reduce noise

    In our example above there are a couple of things I’m going to fix, the stained glass windows are blown out and not nice and there is a lot of noise. In addition the image is not actually level, (my fault setting up the shot in the first place). All of these we will fix in Photoshop.

    Don’t be scared of Photoshop, it’s your friend, learn to love it. If you’re not that up on the Photoshop skills then a quick Google will find you a host of free online tutorials.

    Right, first let’s sort those church windows.

    1. Load your HDR image in to Photoshop and duplicate the layer (ctrl-J or option-J), this is to preserve a copy in case we make a mistake and want to roll back.
    2. Now take a look at your original RAW shots. Looking at my original images the darkest of the shots I took has the best detail in the windows.
    3. Next I load the image in to Photoshop. I do this via Adobe Camera Raw, where I did do a little adjusting on the image to match it more closely with the HDR and to bring on the window details even more.
    4. Then copy the image in to a new layer on the HDR image. With My HDR image on top I add a layer mask to this layer, set the brush tool to about 40% opacity and start to brush in the window area to bring the dark image through the layer.
    5. Once I’m happy with the masking I then merge down the layers in to one. There are times when I have to do multiple layer masking from more than one original raw file, the same process applies.

    If we zoom in to 100% and look around, you can see that there is a lot of noise in the image. Unfortunately this is a common side effect of the whole HDR process. Fortunately, reducing noise is a simple process. The Micro-smoothing slider in the tone mapping area of Photomatix can help with noise reduction when creating the HDR, but I prefer to leave that alone and use the Noise Ninja plugin for Photoshop.

    Again perform the noise reduction on a duplicate layer. The process may remove some details from the image that you wanted to keep so you can Layer Mask them back in again after reducing the noise.

    You’re going to get used to Layer masks when doing HDR images :-)

    And that’s it, All that’s left is to straighten up my image, do a little crop and we’re done.

    St Andrews Episcopal church Altar

    I hope you enjoyed this tutorial. Please feel free to comment below. My methods are always revising as I find new ideas or software; I will try to keep this tutorial up to date for you.

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