Class Name: Colour Index

Superclass - <Colour>

Subclasses

Definition

An instance of this DRM class specifies a reference to a <Primitive Colour> component of a <Colour Table> instance.

A <Colour Index> instance contains an index into the primary <Colour Table> component of the <Colour Table Group> instance to which it is associated. The <Colour Table Group> instance specifies which of its <Colour Table> components is being used, while the <Colour Index> instance specifies which <Primitive Colour> component within that primary <Colour Table> instance is being referenced.

Primary Page in DRM Diagram:

• 14

Secondary Pages in DRM Diagram:

Example

1. Consider a <Colour Table Group> instance, the primary <Colour Table> component of which consists of <Primitive Colour> instances for OTW viewing conditions.

   A <Polygon> instance that references the kth <Primitive Colour> component in this table does so by having a <Colour Index> component that is associated to the <Colour Table Group> instance and the index value of which is set to k. If the <Colour Index> instance is solely responsible for the colour of the <Polygon> instance, its intensity_level is 100.0.

FAQs

Consider a consumer attempting to consume a DRM object, e.g., a <Polygon> instance, the <Colour> component of which is specified by a <Colour Index> instance. What can the consumer do to get access to the actual <Primitive Colour> instance being referred to?

A consumer can access the actual <Primitive Colour> instances contained within a <Colour Table> instance just as though <Inline Colour> instances had been used, via the Level 0 API. See SE_InitializeComponentIterator()'s directly_attach_table_components parameter, and SE_GetComponent()'s directly_attach_table_components parameter.

How can a data provider, specify that a <Colour> instance contributes x percent (e.g., 25%) of the total effect on a coloured object, while an <Image Mapping Function> instance provides the remaining 100%-x (e.g., 75%)?

See the intensity_level field of the <Colour Index> class and the intensity_level field of the <Image Mapping Function> class.

Constraints

• <<Publishable Object>>
• <<Colour Mapping Constraints>>
• <<Presentation Domain Constraints>>

Associated to (one-way)

• one <Colour Table Group> instance

Composed of (two-way) (inherited)

• zero or one <Presentation Domain> instance¹
• zero or one <Translucency> instance

Composed of (two-way)

• zero or one <Colour Index Control Link> instance

Component of (two-way) (inherited)

• zero or more <Aggregate Feature> instances
• zero or more <Aggregate Geometry> instances
• zero or more <Primitive Feature> instances
• zero or more <Primitive Geometry> instances
• zero or more <Property Set> instances
• zero or more <Vertex> instances

Inherited Field Elements

Field Elements

Notes

Composed of Notes

Presentation_Domain

Fields Notes

colour_mapping

The colour_mapping field specifies the set of SE_Colour_Mapping members applicable to the <Colour> instance.

index

The index field specifies which <Primitive Colour> instance is being referenced within the primary <Colour Table> component of the given <Colour Table Group> instance. For a <Colour Index> instance with a <Colour Index Control Link> component X, where the colour_index field of X is non-zero, the value of the index field is obtained from X.

intensity_level

The intensity_level field specifies the proportional contribution of the indexed colour data to the total effect on the coloured object(s). For the RGB and CMY colour models, each of the colour data values within the referenced <Primitive Colour> instance are multiplied by the intensity_level field value to obtain their contribution to the total colour of the affected coloured object(s). For the HSV colour model, only the value component of the colour data value within the referenced <Primitive Colour> instance is multiplied. For a <Colour Index> instance with a <Colour Index Control Link> component X, where the intensity_level_index of X is non-zero, the value of the intensity_level field is obtained from X.