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Tagging Clips with a Colour Space

All media in the application is now tagged with a colour space identifier, for example, "Rec.709 video", "ARRI LogC", "ACEScg", "Matte", etc. Making the application colour space aware allows a mixture of different colour spaces to be used simultaneously in a convenient way by providing a number of benefits:
  • The view transform setting of viewports is automatically updated so there is no need for manual readjustment as different clips, Timeline layers, or Batch nodes are selected.
  • Accurate thumbnails and preview windows can be shown.
  • The behavior of various algorithms may be customized automatically for the clip being processed. For example, the Image Type menu in keyers is now automatically set by default.
  • OpenClips can describe the colour space of the media.
  • There is the flexibility to either convert media upon import to a common colour space, or import in its native state and defer conversion until it may be needed.
  • The application may provide warnings based on colour space.

Methods of Tagging

These benefits of tagging come with the responsibility of ensuring that media is correctly tagged upon import or creation. The application provides a number of methods to tag media such as:
  • Use the Input Rules to automatically tag based on filename and path.
  • Manually tag in MediaHub when importing.
  • Modify Pre-processing settings after import.
  • Insert a Colour Management Timeline Effect in Tag Only mode.
  • Insert a Colour Management Batch node in Tag Only mode.
  • Select a group of clips and use the Edit Colour Space option from the Timeline contextual menu.
  • Set the Tagged Colour Space in generators such as Colour Source
  • Add tagging metadata to OpenClip XMLs to integrate into a facility pipeline.
In some cases, the application assigns tags automatically:
  • When importing media in "From File or Rules" mode and the application is able to determine the colour space from the file. This is the case with camera raw formats such as RED r3d, ARRI Raw, and Sony Raw. Also for OpenEXR files that have the acesImageContainerFlag attribute set to 1.
  • In Batch, the colour space of the Result is generally taken from the Front input. However the Result of nodes that produce mattes are tagged as such.
  • In Action, the optional output passes (mattes, normals, etc.) are tagged appropriately.

Colour space tagging is preserved when Archiving and Wiring media.

Tagging as Unknown

When the colour space of a clip is not known, you may tag it "Unknown". This is what the application does when working with Archives or Wires from libraries created in releases prior to the introduction of colour space tagging. The "Unknown" tag may also be used temporarily to identify media that needs to be retagged later once more information is known about it.

Checking the Tagged Colour Space

The tagged colour space may be shown in various locations:
  • There are file, input, and tagged colour space columns available in the media list view.
  • The input and tagged colour space are shown in the MediaHub Preview panel at the top of the Clip Info.
  • It is shown when you Alt-click on a clip or timeline segment.
  • It may be written on top of clip thumbnails via the setting in User Interface Preferences
  • It is written under many nodes in Batch.
  • It is shown in the lower right corner of many viewports.
However, if the clip is tagged "Unknown", the colour space is generally not shown.

Mixing Colour Spaces within a Sequence

Each frame has its own colour space tag. Therefore via editing it is possible to create a Sequence or even a Segment that contains more than one colour space. The players and the Colour Management effect/node are able to respond to these changes at the frame level.

The fact that the player and viewports respond automatically to the tagging is often convenient when working with complicated Timeline Sequences. For example, your main track could have final scene-linear segments but you could have tracks or segments that are in video colour space as off-line references. However, care must also be taken when creating Sequences that mix colour spaces. For example:
  • Unlike the players and viewports, Export is unable to apply different colour conversions on a per-frame basis. Keeping your Sequences uniform will avoid mixed colour space deliveries.
  • Timeline blends and transitions such as dissolves should be done between elements that are in a common colour space. For example, if the colour space changes during a dissolve, the player view transform may switch causing an apparent artifact in the transition. For transitions such as fade-ins and fade-outs, you may use the Set Sequence Gap Colour Space option from the Timeline contextual menu if you need to override the default gap colour space of a Sequence.

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