ABSTRACT
High dynamic range imaging It is interesting to see how camera sensor technology has evolved over the last few years and speculate what might be in store in the years to come. In time we may see camera sensors become available that are able to capture high dynamic range scenes in a single exposure. However, HDR cameras are not that common yet, so currently it is all about capturing bracketed sequences of images and blending these together to create single high dynamic range images that can contain the entire scenic tonal range. Right now there are a lot of photographers interested in exploring what can be done using high dynamic range image editing. For example, by using the Merge to HDR Pro feature in Photoshop you can combine two or more images that have been captured with a normal digital camera, shot at different exposures, and blend these together to produce a 32-bit floating point, high dynamic range image. You can then convert this 32-bit HDR file into a 16-bit per channel or 8-bit per channel low dynamic range version which can then be further edited in Photoshop. In Figure 7.1 I show some examples of what high dynamic range processed images can look like. You are probably familiar with the typical ‘HDR look’ where there are obvious halos in the picture. While there are photographers who like this kind of effect there has been a backlash against the illustrated feel these images have. A couple of years ago I was asked to help judge the UK’s Landscape Photographer of the Year competition. I thought it was interesting to note that of all the obvious HDR-effect images, not one of these got shortlisted into the final selection. That said, there may well have been some HDR processed images that did make it through, because HDR editing does not have to be about creating artificial-looking images. Basically, high dynamic range image editing requires a whole new approach to the way image editing programs like Photoshop process the high dynamic range image data. Because of this the Photoshop team had to rewrite a lot of the Photoshop code so that some of the familiar Photoshop tools could be made to work in a 32-bit floating point image editing environment. Photoshop therefore now offers a limited range of editing controls such as layers and painting in 32-bit mode. The Merge to HDR Pro feature has been further improved in Photoshop, but as you will read later in this chapter, the new Process 2012 for Camera Raw can also cope very effectively with raw image captures of high dynamic range subjects.
