HDR rendering

In the previous chapters, we have used an 8 bit per-channel texture for accumulating the lighting calculation results. The main drawback of using this format is that all output values get clamped to the range 0 to 1. On top of that, the precision of values an 8 bit per-channel texture can store is very limited. From this point on we will refer to 8 bit per-channel textures as low dynamic range textures, or LDR for short.

When lighting a bright scene, the accumulated light value may exceed the maximum LDR value of 1. Those bright areas then get clamped to the value of 1 and all the bright details get lost. We call this saturation, because the bright areas saturate the value stored in the LDR texture. To make things worse, dark scenes ...

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