High dynamic range (HDR) imaging

High Dynamic Range (HDR) imaging is the process of taking several pictures of the same subject with different exposures and then combining all of them to produce an image with a wide range of intensity levels. In other words, HDR uses the pictures with longer exposure to obtain more detail and color on the darker parts of the picture and does the opposite with the pictures with short exposure. The end result is a picture that is closer to what your eyes actually see.

To produce an HDR image you take several pictures of the same subject using different exposures. You must use a tripod because you want all the pictures to align perfectly. At minimum you will take 3 pictures: one underexposed, one overexposed and one that is just normal (with the ‘right’ amount of exposure), but you can take more using different levels of under and over exposure.


Once you have the pictures, you need an imaging software to merge them. I first tried to follow these instructions using Gimp on my Ubuntu virtual image, but the process was really slow and the result wasn’t very good. Notice how the merged pictures don’t align perfectly:

Then I downloaded a trial version of Adobe Photoshop CS4 and the best thing is that it does all the merging and aligning for you and here is the result of that:

The result looks good, but I’m not impressed. I’ve seen really amazing HDR pictures on the web, so I’m going to keep experimenting with it and post any further progress I make with this technique.