The Low Light Photography Field Guide

Tone Mapping

The final stage in HDR Imaging is to create a viewable 16-bit or 8-bit image from the 32-bit HDR file.

This is neither predictable nor particularly easy to manage, although there are several software methods. Much depends on the original scene, how big a dynamic range it has, and the way you shot it, but for various reasons simply compressing it to fit a 256-level scale is rarely satisfactory. If there are very bright highlights, for example, a simple proportionate compression will result in an overall dark image with insufficient attention paid to the midtones. Because the many tones in the HDR file have to be assigned somehow to the much more restricted low dynamic range (LDR) file, the procedure is called tone mapping. The software ...