Displays & Views¶

`displays`¶

Required.

This section defines all the display devices which will be used. For example you might have a sRGB display device for artist workstations, a DCIP3 display device for the screening room projector.

Each display device has a number of “views”. These views provide different ways to display the image on the selected display device. Examples of common views are:

“Film” to emulate the final projected result on the current display
“Log” to send log-space pixel values directly to the display, resulting in a “lifted” image useful for checking black-levels.
“Raw” when assigned a colorspace with raw: yes set will show the unaltered image, useful for tech-checking images

An example of the displays section from the spi-vfx config:

displays:
  DCIP3:
    - !<View> {name: Film, colorspace: p3dci8}
    - !<View> {name: Log, colorspace: lg10}
    - !<View> {name: Raw, colorspace: nc10}
  sRGB:
    - !<View> {name: Film, colorspace: srgb8}
    - !<View> {name: Log, colorspace: lg10}
    - !<View> {name: Raw, colorspace: nc10}
    - !<View> {name: Film, colorspace: srgb8}

All the colorspaces (p3dci8, srgb8 etc) refer to colorspaces defined later in the config.

Unless the active_displays and active_views sections are defined, the first display and first view will be the default.

A view may be defined as a transform directly from the scene-referred reference space to the display, as illustrated above. Alternatively a view may be defined using the combination of a View Transform and a Display Color Space. In this case, the View Transform converts from the scene-referred reference space to the display-referred reference space and then the Display Color Space is used to convert from the display-referred reference space to the display. Here is an example:

displays:
  DCIP3:
    - !<View> {name: Film, view_transform: FilmView, display_colorspace: DCIP3}

view_transforms:
  - !<ViewTransform>
    name: FilmView
    from_reference: <omitted for brevity>

display_colorspaces:
  - !<ColorSpace>
    name: DCIP3
    from_display_reference: <omitted for brevity>

The keys allowed with a View are:

name: A name for the View.
colorspace: The color space whose transform will be used to convert from the reference space to the display.
view_transform: The transform used to convert from either the scene-referred reference to the display-referred reference space or as a transform to be applied in the display-referred reference.
display_colorspace: The display color space that is used to convert from the display-referred reference space to the display.
looks: One or more Look Transforms to be applied. The string may use the ‘+’ character to apply a look in the forward direction and the ‘-’ character to apply in reverse. See Looks
rule: The viewing rule to be used with this View. See viewing_rules
description: A description string for this View.

Note that a View may use either the colorspace key or it may use both the view_transform and dispay_colorspace keys. No other combinations are allowed.

`view_transforms`¶

Optional. Defines transforms to convert between the OCIO reference spaces.

An OCIO config may contain two Reference spaces: one scene-referred and the other display-referred. The View Transforms are mappings between these reference spaces. There are a variety of terms used in the industry for these mappings. In ISO 22028-1 and in ACES, they are called “color-rendering transforms” and in the ITU standards for HDR television (such as ITU-R BT.2100 and BT.2390) they are called an “Opto-optical Transfer Function” or OOTF.

It is also possible to specify a View Transform for adjusting display-referred reference space values. In other words, it may convert from the display-referred reference space back to itself. This is useful for describing transforms used for HDR to SDR video conversion, or vice versa.

A View Transform may use the following keys:

name: A name for the ViewTransform.
description: A description of the ViewTransform.
family: A family string (similar to ColorSpace).
categories: The categories used for menu filtering (similar to ColorSpace).
from_scene_reference: The transform from the scene-referred reference space to the display-referred reference space.
to_scene_reference: The transform from the display-referred reference space to the scene-referred reference space.
from_display_reference: The transform from the display-referred reference space to the display-referred reference space.
to_display_reference: The inverse of the from_display_reference transform.

`default_view_transform`¶

Optional. Defines the default view transform.

The default view transform is the view transform that is used if a ColorSpaceTransform needs to convert between a scene-referred and display-referred colorspace. If this key is missing, the first view transform in the config is used.

default_view_transform: un-tone-mapped

`shared_views`¶

Optional. Allows a view to be defined once for use in multiple displays.

For example, this:

shared_views:
  - !<View> {name: Log, colorspace: lg10}
  - !<View> {name: Raw, colorspace: nc10}

displays:
  DCIP3:
    - !<View> {name: Film, colorspace: p3dci8}
    - !<Views> [ Log, Raw ]
  sRGB:
    - !<View> {name: Film, colorspace: srgb8}
    - !<Views> [ Log, Raw ]

Is equivalent to this:

displays:
  DCIP3:
    - !<View> {name: Film, colorspace: p3dci8}
    - !<View> {name: Log, colorspace: lg10}
    - !<View> {name: Raw, colorspace: nc10}
  sRGB:
    - !<View> {name: Film, colorspace: srgb8}
    - !<View> {name: Log, colorspace: lg10}
    - !<View> {name: Raw, colorspace: nc10}

A shared view may use the special token <USE_DISPLAY_NAME> to request that the display_colorspace name be set equal to the display name that the shared view is used with. In the following example, when the ACES shared view is used with the sRGB display, its display_colorspace is set to “sRGB” and when it is used with the Rec709 display, its display_colorspace is set to “Rec709”.

shared_views:
  - !<View> {name: ACES, view_transform: ACES-sdr-video,
             display_colorspace: <USE_DISPLAY_NAME>}
  - !<View> {name: Log, colorspace: lg10}
  - !<View> {name: Raw, colorspace: nc10}

displays:
  sRGB:
    - !<Views> [ ACES, Log, Raw ]
  Rec709:
    - !<Views> [ ACES, Log, Raw ]

display_colorspaces:
  - !<ColorSpace>
    name: sRGB
    from_display_reference: <omitted for brevity>
  - !<ColorSpace>
    name: Rec709
    from_display_reference: <omitted for brevity>

As with any other view, a shared view may appear (or not) in the list of active_views.

Application developers do not need to worry about shared views since the API presents them as if they were a typical View.

`active_displays`¶

Optional. Default is for all displays to be visible, and to respect order of items in displays section.

You can choose what display devices to make visible in UI’s, and change the order in which they appear.

Given the example displays block in the previous section - to make the sRGB device appear first:

active_displays: [sRGB, DCIP3]

To display only the DCIP3 device, simply remove sRGB:

active_displays: [DCIP3]

The value can be overridden by the OCIO_ACTIVE_DISPLAYS env-var. This allows you to make the sRGB the only active display, like so:

active_displays: [sRGB]

Then on a review machine with a DCI P3 projector, set the following environment variable, making DCIP3 the only visible display device:

export OCIO_ACTIVE_DISPLAYS="DCIP3"

Or specify multiple active displays, by separating each with a colon:

export OCIO_ACTIVE_DISPLAYS="DCIP3:sRGB"

`active_views`¶

Optional. Default is for all views to be visible, and to respect order of the views under the display.

Works identically to active_displays, but controls which views are visible.

Overridden by the OCIO_ACTIVE_VIEWS env-var:

export OCIO_ACTIVE_VIEWS="Film:Log:Raw"

`virtual_display`¶

Optional. A virtual display may be defined to allow OCIO to instantiate new displays from ICC profiles.

The syntax is similar to a conventional display. It may incorporate both views and shared views. There may only be one virtual display in a config.

When OCIO instantiates a display from an ICC monitor profile it will create a display colorspace which is used with any views that have the display_colorspace set to <USE_DISPLAY_NAME>.

So in this example, if the application asks OCIO to instantiate a display from an ICC profile, the user would then see a second display, in addition to “sRGB”, named after the ICC profile. The views available for that new display are taken from the virtual display.

displays:
  sRGB:
    - !<View> {name: ACES, view_transform: ACES-sdr-video,
               display_colorspace: <USE_DISPLAY_NAME>}
    - !<View> {name: Log, colorspace: lg10}
    - !<Views> [ Raw ]

virtual_display:
  - !<View> {name: ACES, view_transform: ACES-sdr-video,
             display_colorspace: <USE_DISPLAY_NAME>}
  - !<View> {name: Log, colorspace: lg10}
  - !<Views> [ Raw ]

Displays & Views¶

displays¶

view_transforms¶

default_view_transform¶

shared_views¶

active_displays¶

active_views¶

virtual_display¶