March 6th, 2010 by Rick

HDR photography has me excited. I have a decent DSLR camera and can (occasionally) take a good picture. But, some scenes just never seem to look as compelling in the picture as they are in real life. Thinking about it, and reading up about it on the latest photog sites, it became clearer.

Many scenes have such variation between the shadows and the highlights aren’t well replicated in a normal image. It turns out that our eyes can process wider ranges than cameras today can capture – “dynamic range”. So, “high dynamic range” imaging infers that capturing this range is possible with relatively normal cameras. The trick is to capture the full range of the scene by taking a series of pictures, and then combining them into one image. By bracketing exposures and using software to align and combine the photos, this becomes possible.

Bracketing exposures means that you end up taking a normally exposed photo and other photos of the same scene that are under exposed (showing the detail in the highlights of the image) and that are over exposed (showing the detail in the shadows of the image). This series of bracketed images may be 3, 5, 7 or 9 different pictures with the correctly exposed photo right in the middle of the under / over exposed pictures. If you guessed that aligning all of these pictures will be important, you’re right. Software can do a decent job of aligning handheld pictures these days, but it is always best to use a solidly locked down tripod. The idea us to not move the camera at all as the series if shots are taken. There are tips and tricks to getting good, bracketed photos that I won’t get into here.

Processing the series of images and combing them into one requires specialized software. Adobe Photoshop CS4 can do this (and to a lesser degree so can earlier versions) but the current tool of choice us Photomatix. Photomarix takes the series and combines then into a 32 bit image – and it’s ugly until it’s further processed. The reason it’s ugly at this point is because the current monitors don’t display such wide ranges of visual information. There are several post-processing options that allow you to tweak the image to taste. Personal taste here is the key – the output can range from a normal looking image (with the intended amount of dynamic range) through unnatural and unrealistic, oversaturated works of art. The image that’s attached (from my iPod Touch – so it’s small) is one that I took shooting into the sunset. I was trying to get the beautiful mountains and sky, but this wouldn’t have been possible in a normal single picture. The other pictures I’ve included here are other examples of various (and more extreme) processing.

So, for those that are so inclined, study up and give HDR a shot. If you simply enjoy looking at pics, now you know how some of those awesome shots came about!