Using the ACES CDL Grading Mode

Livegrade implements the ACES color pipeline including IDT transforms, working color spaces such as ACEScct and ACEScc, LMT, RRT and ODT transforms to be used on camera live signals and still images (e.g. for reference) on the film set.

The ultimate goal is to create the same visual result on an on-set monitor (showing the ACES-processed live signal of a camera) compared to the monitors in a color corrector (showing the ACES-processed recorded source clips from the camera). Livegrade also offers export of ACES-based looks in the ACES Metadata File format (for ACES version 1.2 and newer).

The following diagram shows an example ACES pipeline as implemented in Livegrade.

Example ACES pipeline in Livegrade

ACES grading modes

Livegrade implements this pipeline in the ACES (Academy Color Encoding System) grading modes. You can see the nodes and controls of the “ACES CDL” grading mode in the screenshot below. On every interaction with the color controls of the ACES grading mode (e.g. change of IDT, modify of ASC-CDL) all transforms are baked together automatically and sent to an attached LUT box.

figure 1: ACES grading controls

Grading controls in the “ACES CDL” grading mode.

Livegrade also offers the “ACES CDL Advanced” grading mode. This grading mode lets you add multiple grading nodes between the IDT and ODT and LMTs for advanced workflows.

You can take a look at how to use the advanced modes in the article Grading Modes in Livegrade.

The CDL controls behave the same way as in the CDL Grade mode and can also be exported as usual from a saved grade. ACES grades can also be exported as 3D LUTs, including the CDL values, IDT and ODT.

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For more information about how to export LUTs: Exporting Grades

Look Modification Transforms (LMTs)

You can add a “LMT” node in Livegrade (in the ACES CDL Advanced grading mode) that supports the official, predefined LMT transforms shipping with the respective ACES version as well as custom 3D LUTs.

Note: LMTs are specified by the ACES specification as a transform from and to ACES AP-0 (the linear ACES color space). When using 3D LUTs as a way to exchange “LMTs”, these 3D LUTs are usually intended to be applied in a typical grading working color space such as ACEScct (3D LUTs cannot properly represent transforms to be applied in linear color encoding as they would not be able to provide the necessary fidelity in all brightness levels). So in Livegrade, the “LMT” node is applied in the working color space (for instance ACEScct).

Managing ACES Versions

Livegrade supports multiple versions of ACES, ranging from 0.7.1, 1.0, to the latest ACES version 1.2. For compatibility with the post production workflow please choose the right ACES version, as the transforms can be slightly different in different versions, and newer version usually include more and more recent input (IDT) and output (ODT) transforms, including RRT+ODT transforms for HDR in ACES version 1.1 and ACES version 1.2.

Please note that only from Livegrade version 5.1.3 transforms for ACES 1.2 can be downloaded.

In the Livegrade preferences you can manage and download the available ACES versions and transforms:

figure 2: preferences panel

figure 2: preferences panel

The dropdown lets you select the ACES version for new looks. Every new look will be initialized with the ACES version selected in the dropdown in the preferences.

Every look in the library made with an ACES grading mode has an associated ACES version (you can find that version in the “ACES Mode” column). Saving looks with different ACES versions to the library will make it easy to compare the look of different ACES versions effortlessly.

In the section “Available ACES Transforms” you can find the available ACES versions and its associated transforms. The icon in the status bar will either signalize an available set of transforms (green checkmark) or a set of transforms that can be downloaded from the servers (download icon with downwards arrow).

Click the button “Check for New Versions” at the bottom of the preferences window to see if new ACES versions are available to download from the Pomfort servers.

Exporting ACES-based Looks as AMF

Livegrade can export the current look of a slot or stored looks in the shot library as AMF files. Currently the export of AMF is limited to the ACES CDL grading mode. See Exporting Shot Information for more details on exporting shot and look metadata from Livegrade.

Devices and Utilization

With Livegrade the ACES grading mode can be used in different setups, e.g. with LUT-Boxes such as the Teradek COLR, FSI BoxIO or TV Logic’s IS-Mini or directly with a monitor such as the Flanders Scientific DM250 broadcast monitor, that has processing capabilities included.

To learn more about the hardware setup of Livegrade see the article about HD-SDI setup for Livegrade.

Please note that for ACES color pipelines a LUT device with a LUT size of 23 or 33 (or higher) is recommended. Otherwise the device might introduce interpolation problems such as bending or wrong levels in some areas of the visible color space.

Supported ACES IDT and ODT Transforms

Livegrade offers all officially (in the Academy’s repository) available IDT and ODT transforms, as well as a few custom transforms by Pomfort. Please take a look at the available transforms in Livegrade’s preferences in the “ACES” tab.

 

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