HDR to LDR conversion with exposure and tone control
Tone mapping compresses the dynamic range of HDR (High Dynamic Range) images to displayable LDR (Low Dynamic Range) values while preserving visual detail. The Reinhard operator (2002) is based on photographic techniques.
Simple Reinhard: L/(1+L) - gentle compression, may lack contrast
Extended Reinhard: Adds white point parameter for brighter highlights
Filmic (Uncharted 2): S-curve with toe and shoulder regions
ACES: Industry standard for cinematic look
The key value (a) represents the target middle-gray luminance, typically 0.18 (18% gray card). Exposure adjusts the overall brightness before tone mapping.