What is HDR?

HDR

I've had a few friends ask me about HDR and what it is. So I thought I would write a short blog on it to help out. Short, only because I only know how to do it (sort of), but know very little about the technical side.

HDR stands for High Dynamic Range. In a nutshell, HDR deals with the range of brightness in a scene. Typically, film or digital sensors have a limited range of dark and light that it can record. However, if we had access to more of the range in the scene, we could adjust the contrast, brightness, etc to enhance the scene to more like we saw it, or even past that. Perhaps into a surreal state taht could not possibly exist.

There are various programs that will perform HDR processing. Photoshop CS2 has the capability if you are using JPG files. However, this will then require at least three (or more, in odd internvals) of pictures of the same scene, but with different exposure values in each one. For example, if you have a scene you want to HDR process, take it at +0 EV, -1 EV, and +1 EV. Several DSLR cameras will do this for you with their Exposure Bracketing feature. The camera will either take the three shots automatically for you with one press of the button, or will require you to press the shutter release three times. I generally don't use Photoshop for HDR processing. Nor do I shoot in JPG format. If you to, remember to use a TRIPOD for your shots, and a remote shutter release if you can (to avoid any camera shake).

The other format you can shot in, which is better for HDR, is Camera RAW. Many DSLRs have this feature. Essentially, the RAW format is a data file of all the information that your camera sensor took in, but with none of the processing that your camera does after the shot is taken (i.e no white balance, colour correction, etc). It also contains more data in the file than can be seen. This allows the photographer to do a single file rather than 3 or more. However, three of more is recommened for best results.

The program I use is Photomatix. It is pretty cheap (about $99 US) and works really well with camera RAW format. Rather than going through how to use it, I will post the link of the site that has the tutorial I found that teaches you how to use it.

For examples of HDR pictures, just check out many of my posts on this site.

Cheers!

Links:

• Photomatix - http://www.hdrsoft.com/
• Photomatix tutorial - http://stuckincustoms.com/2006/06/06/548/
• Photoshop CS2 HDR tutorial - http://www.luminous-landscape.com/tutorials/hdr.shtml