Resolve 17 - ACES DCTL - Not quite there

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RikshaDriver

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Resolve 17 - ACES DCTL - Not quite there

PostTue Nov 10, 2020 11:00 am

Looking at the struct definition of the ACES Transform under the DCTL implementation:

(there's a typo btw... missing the INVERSE_EOTF definition)

typedef struct AcesTransformUserSettingParams
{
float yMin; // Black luminance (cd/m^2)
float yMid; // Mid-point luminance (cd/m^2)
float yMax; // Peak white luminance (cd/m^2)
float displayPri[8]; // Display primaries
float limitingPri[8]; // Limiting primaries
int eotf; // Display device EOTF
int surround; // Viewing environment
int stretchBlack; // Stretch black luminance to a PQ code value of 0
int d60Sim; // Is user D60 adapted
int legalRange; // Output to legal range
int skipRRT; // Skip the standard ACES RRT transform
} AcesTransformUserSettingParams;

This structure seems very rigid and appears designed more for Display referred transforms rather than Scene referred ones.

For example, why would I need to set yMin, yMid & yMax when all I am looking to do for an IDT is an inverse OETF of a camera's mapped scene values?
Specs: i386, 16M RAM, 150MB IDE HDD, Sound Blaster 16, Win NT 3.1

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Hendrik Proosa

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Re: Resolve 17 - ACES DCTL - Not quite there

PostTue Nov 10, 2020 11:16 am

First I thought it might be a boolean to signal whether it is a device EOTF that needs preceeding RRT and thus operates on OCES values but I think you are right, there is a missing line in struct definition.

These luminance values are maybe used by Resolves colorspace aware tools somehow..? Not sure they are actually part of ACES transforms.
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RikshaDriver

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Re: Resolve 17 - ACES DCTL - Not quite there

PostTue Nov 10, 2020 11:18 am

These are the actual descriptions:

Code: Select all
An appropriate ACES transform requires all of the following fields to be defined:
- Y_MIN: black luminance (cd/m^2), value must be float.
- Y_MID: mid-point luminance (cd/m^2), value must be float.
- Y_MAX: peak white luminance (cd/m^2), value must be float.
- DISPLAY_PRI: Display primaries, value must be an array of 8 floats wrapped inside a pair of curly bracket "{}".
- LIMITING_PRI: Limiting primaries, value must be an array of 8 floats wrapped inside a pair of curly bracket "{}".
- EOTF: Display device EOTF, value must be an integer value in range [0-5] corresponding to 5 ACES's defined EOTF, or a custom EOTF function name defined by user.
- INVERSE_EOTF: Input device EOTF, value must be an integer value in range [0-5] corresponding to 5 ACES's defined EOTF, or a custom inverse EOTF function name defined by user.
- SURROUND: Viewing environment, value must be an integer value of 0 or 1 to represent boolean flag.
- STRETCH_BLACK: Stretch black luminance to a PQ code value of 0, value must be an integer value of 0 or 1 to represent boolean flag.
- D60_SIM: Is user D60 adapted, value must be an integer value of 0 or 1 to represent boolean flag.
- LEGAL_RANGE: Output to legal range, value must be an integer value of 0 or 1 to represent boolean flag.
Specs: i386, 16M RAM, 150MB IDE HDD, Sound Blaster 16, Win NT 3.1

My commercial Resolve Looks, Plugins & Transforms: https://xtremestuff.net/store
My Open Source Resolve transforms: https://github.com/xtremestuff
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RikshaDriver

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Re: Resolve 17 - ACES Transform DCTL - Not quite there

PostSat Nov 28, 2020 10:11 am

Looks like in the latest Beta 2 version the "ACES Transforms" reference Documentation has disappeared.
Specs: i386, 16M RAM, 150MB IDE HDD, Sound Blaster 16, Win NT 3.1

My commercial Resolve Looks, Plugins & Transforms: https://xtremestuff.net/store
My Open Source Resolve transforms: https://github.com/xtremestuff

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