The tool is actually a set of tools that span from set to final render. A suite of tools that aim to, as closely as possible, match the lighting that is happening on set when adding visual effects.
Many artists are familiar with capturing an HDR to get the values of illumination at any point on set, but an HDR does not accurately record colour. Such productions actually only record illumination as a relative data set, not directly linked to the real world light or their individual camera gear.
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