I was out catching some landscape photos of fall colors at Mer Bleue Conservation area in Ottawa. I decided that I would shoot some photos to process them as HDR.

HDR horizontal fall landscape Mer Bleue Conservation Area Ottawa

What is HDR? HDR stands for High Dynamic Range. As the name indicates, an HDR photo is a photo that has increased dynamic range compared to a regular photo. In a conventional digital photo, the sensor’s capture abilities cannot match what your eyes sees in terms of contrast ratio. Your eyes/brain can easily adjust and see the full range of information within a scene. For example, in a scene where you have part of the scene in full sunlight and part in full shade, your eyes/brain will adjust and allow you to see the part of the scene lit by the sun and also the part of the scene that is in the shade. Unfortunately you camera cannot capture that full range of information. You will have to compromise and decide between one of:

1) Exposing your image for the sunlit portion of the scene and loose information detail in the shaded portion of your scene.

2) Exposing your image for the shaded portion of the scene and loose detail in the sunlit portion of the scene.

That is where HDR processing comes to the rescue. It allows merging multiple images that were captured at different exposure settings into a single photo covering a larger dynamic range that can look more like the scene you wanted to capture.

Note that many camera models are now being released with the ability to capture in-camera HDR images. Meaning that multiple exposures are taken when you take the picture and they are processed in-camera. However the technique that is explained here can be used with any camera that allows exposure adjustments because the image processing is done on a computer.

There are two main steps in making HDR photos: Capture and Post-processing.

Capture for HDR:

- You need to take three or more exposures of the same scene.

- Use a tripod or some other camera support to ensure that all the exposures that you take are perfectly aligned.

- Frame your composition and set your camera focus.

- The next steps can vary based on the features of your camera. In any case however, the goal is to take multiple exposures while maintaining your aperture setting constant.

1) If your camera has an AEB (Auto Exposure Bracketing) feature, set AEB to take 3 exposures with at least 1 stop over/under exposure. Set your camera to Aperture mode and take your 3 exposures.

2) Set your camera to Manual exposure mode and select your aperture. Take your 3 exposures such that you end up with a properly exposed frame, a frame that is over-exposed by 1 stop and another frame that is under-exposed by 1 stop.

At this point you will have 3 exposures of the same scene with 3 different EVs (0,+1,-1).

Notes:

- The scene that you want to capture will dictate if you should take more that 3 exposures in order to be able to fully represent the scene. The more extreme the more bracketed exposures you should take. It’s obviously better to capture more exposures and ensure that you will be able to generate the desired output.

- If you don’t have a tripod, set your camera to continuous shooting mode and set it to AEB. If your frame rate is fast enough and you stabilize yourself, press and hold the shutter down for the 3 exposures.

3 photos for HDR input

Post processing for HDR

You will now need specialized software to process your photos to generate and HDR image. The most powerful tool out there is Photomatix by HDR soft. Photoshop CS5 also does a good job at processing HDR images. You can also find many free HDR conversion software programs that you may want to try before you commit to buying dedicated HDR processing software.

HDR fall landscape at Mer Bleue Conservation Area in Ottawa

Part of the HDR post-processing is called tone mapping. This is when your selected settings will convert your HDR image to an image that is in 8 or 16 bit that your computer can process. It is during that process that you can make adjustments that can make you image surreal. In the above examples I have taken the processing to those extremes because I wanted to achieve the effect that you can see in the clouds.

If you want to learn more on HDR, you can visit:

- Click here to visit Stuck In Customs., a site by photographer Trey Radcliff which is dedicated to HDR photography. Trey also has a book on the subject called ‘A World in HDR’.