The human eye can adjust to a variety of lighting conditions, discerning detail in shadows as well as bright areas. Cameras, for all of their recent improvements in dynamic range (the range from darkness to light), still cannot capture everything that can be experienced by the human eye. For example, when shooting inside a room with a window to a sunny day in the scene, you have a choice of shooting so that the room has detail and the window is solid white, or the scene outside is discernible but the room disappears into shadow.
High Dynamic Range imaging, or HDR, is a technique designed to address this deficiency. By combining many images of the same scene shot with different settings, a single image can be created that contains detail from the brightest and darkest areas simultaneously.
What this means to the field of cultural heritage imaging is that photographs of objects need no longer lose detail from either the highlights or the shadows, making them more useful to researchers and conservators.
HDR of a Buddha: image rendered using 4 bracketed photos
3 of the 4 images used to create the HDR on the left