Ls_Colourspace (Compatible with IFFS 2017.0.0 and up)

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Converts between various colourspaces, mainly perceptual ones (ColorMgmt already handles most camera and display spaces)

All the spaces use illuminant/reference white D65 and are as follows:

linear sRGB: scene-referred (un-tonemapped) linear with sRGB/Rec709 primaries (you can convert to this space from most camera spaces with a Colour Mgmt node, by first converting to ACES and then using primaries/ACES_to_LinearRec709-sRGB.ctf)

XYZ: the classic CIE 1931 XYZ space with white at Y=1, again useful as an interchange space by using the various CIE-XYZ .ctf options in Colour Mgmt

xyY: the CIE 1931 xyY space where x and y are chromaticities in [0,1] and Y is brightness

Lab: CIELAB 1976 where L is perceptual lightness with white at 1, a* is broadly green/red and b* blue/yellow, both centred around 0.0 so likely using negatives

Lab* (0.5-centred chroma): as above but with a* and b* centred around 0.5, so easier to see and work with

LCHab: cylindrical version of Lab* where L* is as before, but C is colorfulness and H is hue

LUV: CIELUV 1976 space similar to Lab* but better suited for screens and emissive surfaces

LUV (0.5-centred chroma): as above but with u and v centred around 0.5

LCHuv: cylindrical version of LUV

Oklab: recent (2020) perceptual space designed to be similar to but faster and better behaved than the above CIE spaces

Oklab (0.5-centred chroma): as above but with a and b centred around 0.5

HSV: classic hue/saturation/value space used in CG and colour picking - we convert to BT1886 2.4 gamma before converting to HSV, rather than converting from linear colour directly, to better match other apps

HSL: similar to HSV but with higher L values tending towards white rather than saturated colours - we convert to BT1886 2.4 gamma before converting to HSL, rather than converting from linear colour directly, to match other apps (unlike Flameā€™s Separate node which assumes the input is already in video space)

YCbCr: YUV space used in digital video with Y including head/footroom and Cb/Cr centred around 0.5

YPbPr: YUV space used in analog video with Pb/Pr centred around 0

lewis _at_ lewissaunders.com


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Older versions that shader

29th of September 2022

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fixed icon

29th of September 2022

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initial upload from commit f62868cadf3e758dc18725f138273b9c1d4b894a


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