High
Dynamic Range
Rendering
High Dynamic Range Rendering
(HDRR), sometimes also called High
Dynamic Range
Lighting, is a special Image
Based Lighting
(IBL) technique in 3d computer graphics to illuminate a
virtual scene using a spherical image instead of standard light shapes
such as point lights, area lights and spot lights. Here, the luminance
distribution of the image is used to model the light distribution of
the 3d scene. Standard images with 256 different levels for each color
channel (RGB) are not sufficient to
achieve realistic looking results.
Therefore, images have to be used with a very large dynamic range.
Those images can be produced by taking standard (low dynamic range)
images with different levels of exposure, which are combined to an HDR
image (HDRI): 
Illustration
of HDR image creation using a multiexposure technique. False color
image of HDR radiance and tone mapped image are shown on the right. Photo:
Axel Jacobs.
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Obviously,
HDR images cannot be displayed on standard monitors with their limited
dynamic range of 3*256 different luminance values. Therefore, a Tone Mapping
technique has to used to convert HDR images back to low dynamic range
images while preserving the image details and color appearance of the
original HDRI.
HDRR
= HDRI + IBL + Tone mapping
Example
of lighting a virtual scene using HDRI. Photo: C.
Malerczyk.
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Cathédrale
Saint-Étienne de Cahors. Photo: Franck Nhieu
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HDR
image of Fort de Vezelois. Photo: Thomas Bresson.
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HDR
image
of a barn. Photo: Florian Wittwer
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Kitchen
table scene illuminated by HDRI. Photo: Miles Bader
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