Guarding the Beaches of LA, by Stuck in Customs on Flickr

Old solution to this problem

If you were facing such a scene in the old days of film, you had to analyze the scene and determine what the key tones were. Often, you needed to hold the highlights and allow some clipping in dense shadows or other dark areas. Sometimes the key tones were dark and you were forced to allow blown highlights. And in some cases, you would decide that the scene couldn’t be compromised. In other words: you couldn’t capture it the way you wanted, so you didn’t!

Thank the spirits we now live in a digital age! Now you can capture this scene using HDR.

My two cents in the HDR argument

Before I move on, I want to address the fact that HDR is frowned upon by some people. There are several reasons for this. Some claim that bracketing or multi-exposure shooting is counter-skillful (elitists). Others think that using HDR is “cheating”, creating a falsified representation of “reality”.

Ignore those people.

HDR is not cheating. Nor is it the path to enlightenment. It’s just another tool in your photography toolbox, to be pulled out when you feel the situation demands it.

Enough ramble! Let’s get on with the subject!

What is HDR photography?

HDR photography is the principle of using multiple shots to capture a high range scene, and then merge these shots together digitally on a computer during post-processing.

The process involves using specialized software tools. These tools will use the different exposures to create an “optimal” representation of the scene, ensuring that the clipped shadows or highlights are excluded from the resulting image. A little simplified, this enables you to expose detailed information in the shadows from the brightest exposures, and details in the highlights from the darkest exposures.

Old suitcase scene analysis

As you can see in the above image, the scene has a high range between the sun on the wall and the suitcase interior. When the interior is correctly exposed, the wall light is completely blown out. And when the sun on the wall is correctly exposed, the photo is underexposed overall, and almost all detail inside the suitcase is lost. To capture this scene, HDR is necessary.

HDR is in its infancy

HDR is still in its infancy. This means that although we’ve had it a few years in still photography, the tools and techniques are going to grow a lot more mature in the future. Camera manufacturers will definitely make use of HDR in some sort in future models to increase their cameras’ ability to cope with high dynamic range scenes.

And also, the tools for post-processing will grow much more mature. Still, some of the tools we have today are already relatively sophisticated. With proper knowledge we are able to create high quality HDR images.

Building the scene

Our own vision is rather limited for taking in a scene as a whole. But our mind has a wonderful way of compensating for this. Our eyes rapidly move around the scene, registering it bit by bit, and our mind then combines these visual impressions into one experienced scene. The brain is also an expert in completing known things where only a part is visible. If we see a car where half of it is hidden by a corner, our brain completes the car for us.

When moving around like this, our eyes quickly adjust to the light and tones of the different areas. And that is pretty much the same as we do with multiple exposures for HDR, except that the camera captures the whole scene in every shot. But we expose for limited areas with each shot.

So, in a sense, one might argue that HDR is more “natural” than capturing a scene with one shot!

Capturing the scene

First and foremost; if you have the choice: use a tripod! Slight movement from hand-held shooting can be compensated by the software, but you will be so much better off by making sure your image data is of the highest possible quality!

How many exposures you need will depend on the given scene. Often, around five exposures are needed. Today, most SLR cameras have a clipping indicator you can enable on the screen, and most also have the option to show a histogram.

Start out by under-exposing the scene. Under-expose to such a degree that the histogram is jammed up on the left side of the histogram, clipping the shadows. Slow down the shutter 1 full stop, and take a second shot (yes, the shutter; the aperture is fixed during HDR shooting!). Slow down another full stop, and take another shot.

Continue shooting in full-stop steps until the darkest part of the histogram is around the center of the scale. (Yes, that means that I should have shot at least one, maybe two stops more in the example shot!) This ensures you record all details in the darkest shadows.

HDR shooting sequence with histograms

Pitfalls when shooting for HDR

There are some pitfalls when shooting for HDR. Among the most common are ghosting, flare, banding and haloing. Ghosting is caused by movement, flare by light from a bright light source. Haloing and banding usually occurs when there are sharp edges between light or dark in the scene. Common examples are around the edges of a window in interior scenes, and at the edge between a dark building wall or roof and a bright blue sky.

I will return to these pitfalls in a follow-up article on HDR tonemapping.

Merging into a HDR image

There are several tools on the market for generating HDR images. I will focus on Photomatix as this is the oldest (and probably best-known) tool out there.

In this introductory article I will not go into details on how to tonemap. I only adjusted a little, mostly the saturation slider. You can experiment with this a little on your own. In a follow-up article I will delve deeper into the technicalities of producing the best possible result using tonemapping.

In Photomatix, click the Generate HDR image shortcut. In the following dialog, browse and select the sequence of photos.

The next dialog is the Options dialog. I recommend that you always check the “Align source images” choice, even when a tripod was used.

Then click the “Generate HDR” button. Photomatix then merges the photos and generates an HDR image. The resulting temporary image then shown is unprocessed and does not show the full range. Your next step is to click the “Tone Mapping” button. This will produce an image where you see the full details in both shadows and highlights.

As stated previously, this article will not cover the tone mapping process. Feel free to play around with the various sliders and see how they affect the photo.

Old suitcase HDR (non-optimized), by Marius Waldal

As you can see above, the various exposures have merged into one photo where both the highlights and the shadows are held, and all details are shown.

I hope this introduction was helpful and that you are hungry for more! I will revisit this subject in a later post with more detailed info on how to perform successful tone mapping!

If you liked this post, you may also like:

1. How to simulate cross-processing in digital photography
2. How to create a black&white image with selective colors in Photoshop
3. Introduction to digital black & white photography