A script’s lookup tables are curves that control the conversion between file or device color spaces and Nuke’s internal color space. In the Curve Editor, the x axis represents the input pixel values and the y axis the output pixel values (normalized to the 0-1 range). When applying LUTs, Nuke looks up the input value along the x axis to determine what the y value is to output.
Nuke provides the following set of default LUTs: linear, sRGB, rec709, Cineon1 The Cineon conversion is implemented as defined in Kodak’s Cineon documentation., Gamma1.8, Gamma2.2, Panalog2 The Panalog LUT is based on a log2lin conversion with a blackpoint of 64, whitepoint of 681, and a gamma of 0.89. , REDLog3 The REDLog LUT is based on a log2lin conversion with a blackpoint of 0, whitepoint of 1023, and a gamma of 1.022., ViperLog4 The ViperLog LUT is based on a log2lin conversion with a blackpoint of 0, whitepoint of 1023, and a gamma of 1.0., AlexaV3LogC5 The Alexa LogC LUT uses the formula provided by ARRI., PLogLin6 The PLogLin LUT uses the default values for the formula, mapping log 0.43457 (code value 445 on a 1024 scale) to linear 0.18 (mid-gray) assuming a negative gamma of 0.6 and a density per code value of 0.002. (This does factor in the fact that value ranges for a log image in Nuke are still scaled to 0-1 range.), SLog7 The Sony S-Log LUT comes from the Sony S-Log Whitepaper Version 1.110. For more information, see http://www.sony.co.uk/res/attachment/file/66/1237476953066.pdf. , and REDSpace8 The REDSpace LUT is implemented as defined in a curve provided by RED..
You can also create an unlimited number of additional LUTs and edit or remove existing LUTs in the script’s settings.
By default, Nuke uses certain LUTs for certain file types or devices. In most cases, you do not need to touch these defaults. However, there may occasionally be cases when changing the defaults is necessary: for example, if your material has been shot with a camera that records in a custom color space, such as Panalog. In those cases, you can change the defaults in the script’s settings so that you don’t need to change the color space on each Read or Write node.
If you do not want to use the default LUT for reading or writing certain individual images, you can select the LUT to use in the corresponding Read or Write node’s controls.