Tone Mapping
Compressing a high dynamic range image into the limited range a screen or print can show, while preserving apparent detail.
In depth
Global mapping applies one curve to the whole image and looks natural but flattens local contrast. Local mapping adapts to each region, preserving detail everywhere — and, pushed too far, producing the halos, grey skies and unnatural glow that gave the technique its bad name. Restraint is almost entirely what separates good HDR from bad.
Examples in practice
Gentle local tone mapping keeps both the cathedral's stained glass and its shadowed vaulting readable without halos.