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Tuesday, August 28, 2007

Creating HDR Images

I just came across this post from Ryan McGinnis over at Backing Winds via Friend-of-the-Blog Jeff Revell.

Both Jeff and Ryan take us through the process of creating HDR (high dynamic range) images using Photoshop CS2's (and CS3's) "Merge to HDR" function.

I have never done anything with HDR myself, mainly because I was never sure about what it was or how it worked. Basically, when your scene has a wide range of tonal values where you want to keep as much of the detail in the highlight and shadow areas of your image as possible.

With HDR, you merge multiple images of the same scene taken at different exposures in order to create a photo that is closer to what you actually see with your own eye.

Ryan McGinnis' post on Backing Winds does a great job of taking you step by step through the process. One thing he mentions, though, that is important to note is what you need to do in-camera prior to uploading the files to your computer.

  1. Shoot in RAW. RAW files, by their nature, carry more dynamic range and are better for creating HDR images.
  2. Use a tripod. Because you will be merging multiple exposures of the same scene, it is a must that your camera is locked down. If possible, use a cable release.
  3. Use your camera's bracketing function. Many DSLRs have an option that will automatically adjust the exposure by a set increment each time your trigger the shutter for a set number of shots (at least 3 but 5-7 is recommended). Your camera will take a "properly" exposed version, one underexposed, and one over exposed - or more if you choose to take 5-7.
Once you create your HDR image (now a 32bit image) you will want to convert it to 16bit. When you make the conversion you'll have the chance to adjust a curve to bring out the most detail and contrast for your shot.

Have fun!