Thursday, August 21, 2008

"Flickr HDR" vs. "The real thing"

Sometimes, terms tend to establish with just a portion of the original meaning. This also seems to apply to HDR imaging. If you follow the threads and images on various photo discussion boards and platforms, you will notice: most times, HDR is meant for a certain look, not for the technology itself.

To help to understand the difference, Erik Reinhard - on of the pioneers of HDR imaging - wrote an article about "Flickr HDR" which is worth reading.

Why care?
If you want to be able to master the various problems and pitfalls of HDR, you have to be able to understand exactly, what type of image you're actually working on. I personally prefer to distinguish between 3 types of images - each one with important differences in workflow (e.g. tonemapping):

  • LDR: That's what you will certainly use most of your times. It is the range, your camera can capture with one shot (no matter if you use JPEG or RAW).
  • MDR: Images with extended range, typically a bracketed image. Still, this image will not contain the full dynamic range of the scene you capture.
  • HDR: This is "The real thing". Everything (all brightness and color), including the light source itself is included in the image. Thus, such images can even be "reversed" by using them as a light source, e.g. for computer generated scenes - called image based lighting (IBL).
Just for the sake of funny comparisons:
Please do not forget: This is not to critizise the artistic value of an image - we're talking about the technology!