High Dynamic Range (HDR)

Editor    August 19, 2016

Why High Dynamic Range?

HDR is a technique for combining two (or more) shots of the same high contrast subject in order to obtain good reproduction of both the highlights and the shadows.  For example one of these images shows the foreground well, which is in shadow, and one the sky.

IMG_7012 Westmill Lane     IMG_7010 Westmill Lane

The technique is useful because the camera sensor can only capture a finite range of light and dark tones, such as a bright sky and dark shadows in the same scene.  With a high contrast scene it can be very difficult to get good detail in the shadows without blowing out the sky.  The HDR technique is essentially to combine two images, one exposed for the shadows and one for the highlights.

How to do it?

First take two photos of your subject, exposed for the highlights and the shadows.  It is not necessary to use a tripod, but try and keep them aligned – the examples are hand-held.  Then process with suitable software.

Both Photoshop and Lightroom provide facilities for creating HDR images, or there are a number of other software packages available such as the free software reviewed at www.techsupportalert.com/best-free-high-dynamic-range-hdr-software.htm.  (I cannot make a recommendation since I have not used any of them.)

Lightroom as an example is very easy to use.  To create an HDR image:

  • From the Library view, select the source images you want.
  • From the menu select Photo -> Photo Merge -> HDR
  • That’s it – when the preview is displayed, click Merge to create the final image.

This is an HDR image produced in Lightroom from the two images above.

IMG_7012 Westmill Lane-HDR

It is possible to quite a lot using the levels adjustments in software like Lightroom, especially if the images are shot in RAW, but you are still limited by the range of tones captured in the original image.  Once a highlight is blown you can’t get it back.