Essentially HDR generation is a two step process. First you merge your differently exposed images into a single 32-bit HRD image. These though do not display very well on your screen because of the limitations of most monitors. Step two is to process the image via Tone Mapping which reveals the dynamic range which can be displayed on a monitor and subsequently printed. There are two tone mapping methods for processing the HDR image; Detail Enhancement, and Tone Compressor.

Detail Enhancement takes into account the local brightness context and you have a number of sliders and selections that you can use to get just the look that you want. The Tone Compressor works on a more global operator. That is the Tone Compressor is applied to the entire HRD source image

Along with the two step process described above, there is a single step process called Exposure Blending. With this, Photomatix will combine differently exposed images to show detail in both shadows and highlights. This does not always work as well when the dynamic range of the scene is high and may give a flat look to the image.

It is easy at first to disregard HDRI as a gimmick and at first I did, but as I started to study it and look at it in relationship to the real world, I find that it does more to emulate reality than what a traditional photo is able to accomplish.

If you look at the series of three images, image number one is what my camera took. For this demonstration, I really did nothing to enhance the photo. Could I have done things differently in taking the photo? Sure, but because of what was going on in the sky with clouds and the various ranges, there would have been compromises.

As I said earlier, the standard method for creating an HDR image is to bracket your exposures. In this instance, I took this image a long time ago and only had this one image so in this case I used Photoshop to bracket my images. Using an adjustment layer I created two more images; one at a minus 2 and one at a plus 2 and saved each of them.