aces 1.0: theory and practice...acescc & acescct: film-style spaces for color-grading •...

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ACES 1.0:Theory and Practice

Welcome

SMPTE Education Webcast Series is sponsored by:

Professional Development AcademyEnabling Global Education

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Thank you to our sponsors for their generous support:




Your Host

Joel E. Welch

Director of EducationSMPTE


Today’s Guest Speakers

CTO

Frame by Frame

Digital Workflow Supervisor

Founder, Kiwii Digital Solutions




ACES 1.0:Theory and PracticeWalter Arrighetti, PhD, CISSP®

CTO, Frame by Frame

Francesco GiardielloDigital Workflow Supervisor | Founder, Kiwii Digital Solutions


Academy Color Encoding System

• Born in 2004 as IIF (Image Interchange Framework), then name was changed in 2012 to ACES

• Academy effort coveting scientists, engineers and artists from the industry

• Color Management for Media & Entertainment (film & animation)

• Encoding for color data, metadata, file and transport formats.

• System made up of several core components and SMPTE Standards targeting interoperability.




Up to 2016, over 100 theatrical & TV shows have used ACES,

…with similar figures in commercials & documentaries overall.

Shot on ACES


Up to 2016, over 100 theatrical & TV shows have used ACES,

…with similar figures in commercials & documentaries overall.

Shot on ACES




Core Components and Reference

• Specifications:• color encoding and metric specs• file formats’ specs• Color Transformations (in CTL language)• Reference Implementation (open source code)

• Reference Images (+ calibration targets for film scanners/recorders)

• Documentation on software and tools

• ACES Central portal, acescentral.com

• SMPTE Standards’ family ST2065

• AMPAS website, www.oscars.org/aces

• Official GitHub repository, https://github.com/ampas/aces-dev


ACES Framework at-a-glance

http://acescentral.com/

http://www.oscars.org/science-technology/aces/

https://github.com/ampas/aces-dev




First Problem Solved by ACES…


Problem 1: Different Camera Sensitometry




Before ACES:

Robust and thorough Color Science required before principal photography


Camera-matching




Camera-matching


Postproduction paradigm056 001 V C 04:14:37:24 04:14:38:17 00:03:20:13 00:03:21:06 057 GUERRILL V C 04:12:25:24 04:12:26:16 00:03:21:06 00:03:21:23 058 GUERRILL V C 03:13:18:20 03:13:19:12 00:03:21:23 00:03:22:15 059 GUERRILL V C 06:11:34:16 06:11:35:24 00:03:22:15 00:03:23:23 * FROM CLIP NAME: GUERRILLA EDL33.MOV* COMMENT: FINAL CUT PRO REEL: GUERRILLA EDL REPLACED BY: GUERRILL

from

Editorial

Audio Sync

digital negs.

10~100

TB/movie

raw processing

noise/grain mgmt

Conforming

VFX, CG,

compositing titles & subtitleslocalization




ACES2065-1(AP0)

ACES2065-1(AP0)

Problem 2: Interoperability in post

titles & subtitleslocalization

Color

Grading

ACEScg(AP1)

raw processing

noise/grain mgmt

ACEScc or ACEScct

(AP1)

VFX, CG,

compositing

Conforming

digital negs.

102~103 TB/movie


Problem 3: Plethora of Delivery Formats

• Every studio, broadcaster, (S)VoD provider, ad distributor, film archive has its own delivery / archival standards

• This rarely includes uniform color encoding

• Some SMPTE standards (IMF, DCDM) help,• Yet no consistent colorimetry specs existed

• Need to future-proof archived content via an open standard for original looks to be easily reproducible years from now




Product Partners & Logo programto guarantee interoperability

• Postproduction pipeline should be done with compatible toolsas much as possible (Product Partners’, but not limited to them)

• Product that receive the ACES Logo (in their respectivecategories) are guaranteed to be interoperable with each other

• Adherence to User Experience (UX) Guidelines facilitates lessexperienced / non-technical users (TB-2014-002)

Internal processing in

ACES color spaces.


ACES Color Management056 001 V C 04:14:37:24 04:14:38:17 00:03:20:13 00:03:21:06 057 GUERRILL V C 04:12:25:24 04:12:26:16 00:03:21:06 00:03:21:23 058 GUERRILL V C 03:13:18:20 03:13:19:12 00:03:21:23 00:03:22:15 059 GUERRILL V C 06:11:34:16 06:11:35:24 00:03:22:15 00:03:23:23 * FROM CLIP NAME: GUERRILLA EDL33.MOV* COMMENT: FINAL CUT PRO REEL: GUERRILLA EDL REPLACED BY: GUERRILL

from

Editorial




Entering an ACES pipeline:Input Transform (IDT)

• Academy Procedure for creating Input Transforms(IDT, P-2013-001)

• Manfacturers can supply their IDTs to Academy for inclusion in the Reference Implementation as CTL files, and/or

• Product Partners can integrate IDTs in their logo’edsoftware (e.g. SDKs).


Entering an ACES pipeline:Input Transform (IDT)

• Academy Procedure for creating Input Transforms(IDT, P-2013-001)

• Manfacturers can supply their IDTs to Academy for inclusion in the Reference Implementation as CTL files, and/or

• Product Partners can integrate IDTs in their logo’edsoftware (e.g. SDKs).




Out of the ACES pipeline:Output Transforms

• ACES color spaces are nevermeant for viewing (as they are scene-referred).

• Every Output Transform ismade up of:

• a common part, RRT to a «reference viewing environment» in display-referred space

• a device-dependent part, ODT to a specific color space/encoding/gamut and technology

• Output Transform may target diofferent display technologies / lighting environments / maxluminance


Out of the ACES pipeline:Output Transforms

• ACES color spaces are nevermeant for viewing (as they are scene-referred).

• Every Output Transform ismade up of:

• a common part, RRT to a «reference viewing environment» in display-referred space

• a device-dependent part, ODT to a specific color space/encoding/gamut and technology

• Output Transform may target diofferent display technologies / lighting environments / maxluminance




ACES Color Spaces

• All based on RGB color-additive model

• Scene-referred colorimetry

• 2 sets of color primaries / whitepoints: AP0 and AP1

• 3 different transfer characteristics: 1 linear, 2 «logarithmic»

• Due to different purposes& costrains


ACES2065-1 main color space

• Central color space for ACES workflows (ST2065-1, TB-2014-004)

• Uses AP0 primaries

• Radiometrically linear («gamma-1.0»)

• Uses ≥16-bit Floating-point codevalues

• Preferred storage encodings are:• OpenEXR image with mandatory metadata

and special flag (ST2065-4, TB-2014-006)Ideal for frame-per-file sequences

• MXF file container wrapping a sequence of ST2065-4 frames (ST2065-5)Ideal for single-file videos

• Elective format for any kinds of storage, as well as for long-term archival.

CIE X′Y′Z′ color space (used for D-Cinema DCDM) is colorimetric, not scene-referred




ACEScg for CG applications

• Conceived for modeling, compositing, matte painting, etc. (S-2014-004)

• Uses AP1 primaries for alignment of RGB operators from non-color-managed applications

• Radiometrically linear («gamma-1.0») for lighting applications

• Represented in floating-point arithmetics

• Negative values are allowed as Out-of-Gamut (OoG) codevalues, but notall applications behave well with them

• Designed as working-only space, notfor storage


ACEScc & ACEScct: film-style spaces for color-grading• Conceived for color correction & grading

operations(S-2014-003 and S-2016-001)

• Use AP1 primaries for more responsecontinuity of grading operators.

• «Log.» characteristic emulates film-printtonecurves:

• ACEScc is a base-2 logarithm,• ACEScct has smoother and higher «toe»

for better emulation of film-look behaviourin the shadows.


• Designed as working-only space, not for storage




ACEScc & ACEScct: film-style spaces for color-grading• Conceived for color correction & grading

operations(S-2014-003 and S-2016-001)

• Use AP1 primaries for more responsecontinuity of grading operators.

• «Log.» characteristic emulates film-printtonecurves:

• ACEScc is a base-2 logarithm,• ACEScct has smoother and higher «toe»

for better emulation of film-look behaviourin the shadows.


• Designed as working-only space, not for storage


ACESproxy for color transportinteger-arithmetics channels• Conceived for transport of images via

devices with lower computing capabilities (S-2013-001)

• SDI cables & devices• broadcast / reference monitors• lower-precision LUT boxes

• Use AP1 primaries and the sametonecurve as ACEScc.

• Represented in integer arithmetics(10bits or 12bits per channel)

• Video-legal codevalue range

• Transport-only color space: meant for neither encoding, processing norstoring images

• No «integer»-analogue to ACEScct




ACESproxy for color transportinteger-arithmetics channels• Conceived for transport of images via

devices with lower computing capabilities (S-2013-001)

• SDI cables & devices• broadcast / reference monitors• lower-precision LUT boxes

• Use AP1 primaries and the sametonecurve as ACEScc.

• Represented in integer arithmetics(10bits or 12bits per channel)

• Video-legal codevalue range

• Transport-only color space: meant for neither encoding, processing norstoring images

• No «integer»-analogue to ACEScct


Codevalue ranges compared




ACES Color Pipeline056 001 V C 04:14:37:24 04:14:38:17 00:03:20:13 00:03:21:06 057 GUERRILL V C 04:12:25:24 04:12:26:16 00:03:21:06 00:03:21:23 058 GUERRILL V C 03:13:18:20 03:13:19:12 00:03:21:23 00:03:22:15 059 GUERRILL V C 06:11:34:16 06:11:35:24 00:03:22:15 00:03:23:23 * FROM CLIP NAME: GUERRILLA EDL33.MOV* COMMENT: FINAL CUT PRO REEL: GUERRILLA EDL REPLACED BY: GUERRILL

from

Editorial


LMT for Creative Color Operations

Every «inter-ACES» color mapping (thus IDT/RRT/ODT are not), applied to the whole image, that is not (just) a color-space conversionbetween the 5 ACES encodings (TB-2014-010)

• Creatively there can be more than one LMT applied to the samescene on top of each other (yet the stacking order does matter)

• Different scenes usually get different LMTs

• Examples of LMTs are (but not limited to):• Local mathematical operations on the whole image (e.g. RGB-matrices, color

curves, …, but not convolution filters, …)• Primary color grades• On-set or near-set grades represented as Color Decision Lists (CDLs)• Pre-defined LUTs/formulas emulating specific ‘looks’ (monochrome, bleach-

bypass, …)




sRGB vs DCI X′Y′Z′


sRGB vs ACES2065-1




ACES2065-1 vs ACEScc


Color Space comparison

sRGBreference:

γ = 2.2

peak lum. = 100nits

whitepoint = D65





Rec.2020

γ = 2.4

peak lum. = 1knits

differences with:

sRGB



DCI P3

γ = 2.6

peak lum. = 48nits

whitepoint = DCI

differences with:

sRGB





DCI X′Y′Z′

γ = 2.6

peak lum. = 48nits

Realcolorimetricspace



ACES2065-1

not meant for directviewing





ACEScg

working color space


subtraction from:

ACES2065-1



ACEScc

working color space


subtraction from:

ACES2065-1





ACEScct

working color space


subtraction from:

ACEScc



ACESproxy

transport only


Video-legal levels

not to be stored




Non-ACES color stack

viewingLUT

• Original footage is usually in some «log» encoding (35mm film-densityLog10 encoding?) This is sort of HDR where important re-exposure of the scene can still be made.

• Color correction layers are appliedon top of this «log» space.

• Viewing LUT is applied beforemonitor / projector throughout the process

• Output LUT (e.g. a Print Film Emulation), is applied before finalrendering to the delivery color space.

3D LUT


ACES color stack

ACES2065to

ACEScc(t)

LMT




Example from a real production

On-Set / Near-Set:• Cameras: ARRI Alexa (ARRIRAW), RED (R3D), GoPro (MPEG4 QuickTime),

mobiles

• Color Spaces: ARRI Log.C + other camera-native’s

• Reference monitors calibrated and aligned with the post lab’s

• Miscellaneous, yet standard equipment (e.g. Pomfort LiveGrade)

Postproduction / Digital Intermediate / Finishing:• FilmLight Baselight

• Cross-calibrated theatre projector and broadcast monitors

VFX• Autodesk Maya 2017 for modeling and animation

• The Foundry Nuke X + Studio for compositing


On-set / near-set Workflow




Postproduction Workflow


VFX Workflow




Rec.709 DPXs

SMPTE2065-4 OpenEXRswithout CDL

Color Pipeline for the Tests

ACES2065to

ACEScc(t)


Pre-shooting ACES tests

• Camera dept. shoots camera-raw files for all photography sets

• On-set color-grading using CDL (on top of ACEScc)

• Camera dept. sends to the lab:• Camera-raw files• CDLs• SMPTE2065-4 renders (16bpc OpenEXR) of selected stills with just Input

Transform applied – with and without their CDLs• Renders of the above stills + Output Transform to Rec.709 (10bpc DPX)

• «Post» lab processes the camera-raw with Baselight:• Working c.s. is ACES2065-1; Grading c.s. is ACEScc• CDLs are applied• Renders are generated of the same EXRs and DPXs from camera dept.

• Photoshop comparison (in 32bpc environment) of the same frames




Pre-shooting ACES tests results


Pre-shooting ACES tests, zoomed




Pre-shooting ACES tests, zoomed


VFX ACES turnaround tests




ACESclip: Clip-level metadata

XML sidecar file describing all the color-relatedmetadata of a still or moving picture (TB-2014-009) like:

• the «past» color transformation(s) it is baked with

• its current colorimetry

• the intended ouput /viewing environment

• in a word, its «color pedigree»

Pairs also (and above all) «non-ACES» files

May contain other metadata (TimeCode, LMT, …)

It is linked to the clip via UUIDs that must be honored


Color Transformation Language

• It is a C-like programming languagefor color operations (S-2014-006)

• All ACES color transforms (IDTs, ODTs, LMT, …) are written and distributed as CTLs

• It is intended only for developers of ACES-compatible tools

• It is structured as a Color Management Library

• Academy-provided CTLs have a TransformID as UUID’s

float[3] restore_hue_dw3 (float pre_tone[3], float post_tone[3])

{

int inds[3] = order3(pre_tone[0], pre_tone[1], pre_tone[2]);

float orig_chroma = pre_tone[inds[0]] - pre_tone[inds[2]];

float hue_factor = ( pre_tone[inds[1]] - pre_tone[inds[2]])/orig_chroma;

if(orig_chroma==0.) hue_factor = 0.;

float new_chroma = post_tone[inds[0]] - post_tone[inds[2]];

float out[3];

out[inds[0]] = post_tone[inds[0]];

out[inds[1]] = hue_factor * new_chroma + post_tone[inds[2]];

out[inds[2]] = post_tone[inds[2]];

return out;

}

float moncurve_r(float y, float gamma, float offs)

{ //// Reverse monitor curve ////

float x;

const float yb = pow(offs * gamma / ((gamma-1.0)*(1.0+offs)), gamma);

const float rs = pow((gamma-1.0)/offs,gamma-1.0)*pow((1.0+offs)/gamma,gamm

if(y>=yb) x = (1.0+offs) * pow(y, 1.0/gamma) - offs;

else x = y*rs;

return x;

}




CommonLUT Format

Comprehensive XML-based Color LUT file format (S-2014-006).

It can accomodate many stacked color operations (processes):

• 1D or 3D Color LUT

• ASC CDL

• Color matrices

• …

Has metadata for input/output digital colorspace descriptions

Still limited support by Product Partners (Autodesk Flame / Lustre, FilmLight Baselight / Truelight, Light Illusion LightSpace, …)


ACES Framework at-a-glance




Thank you !


Questions

CTO

Frame by Frame

Digital Workflow Supervisor

Founder, Kiwii Digital Solutions




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aces 1.0: theory and practice...acescc & acescct: film-style spaces for color-grading •...

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