DICOM PS3.3 2021b - Information Object Definitions

C.9.3 Multi-frame Overlay Module (Current)
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### C.9.3 Multi-frame Overlay Module

Table C.9-3 specifies the Attributes of a Multi-frame overlay, or of a single frame overlay applied to a specific image frame. This Module specifies additional attributes for overlay planes specified in Section C.9.2 Overlay Plane Module. All Overlay frames have the same characteristics.

A Multi-frame Overlay is defined as an Overlay whose overlay data consists of a sequential set of individual Overlay frames.

### Note

A Multi-frame Overlay is encoded as a single contiguous stream of overlay data. Neither frame delimiters nor padding between overlay frames are contained within the overlay bit stream. See Section 8.1.2 Overlay Data Encoding of Related Data Elements in PS3.5 .

A Multi-frame Overlay applies only to a Multi-frame Image.

Table C.9-3. Multi-frame Overlay Module Attributes

Attribute Name | Tag | Type | Attribute Description
--- | --- | --- | ---
Number of Frames in Overlay | (60xx,0015) | 1 | Number of Frames in Overlay.
Image Frame Origin | (60xx,0051) | 1C | Frame number of Multi-frame Image to which this Overlay applies; frames are numbered from 1. Required if the starting Image frame number to which this Multi-frame Overlay corresponds is not 1. May be present otherwise.

#### C.9.3.1 Multi-frame Overlay Attribute Descriptions

##### C.9.3.1.1 Number of Frames in Overlay

The total number of frames contained within a Multi-frame Overlay is conveyed in the Number of Frames in Overlay (60xx,0015).

The frames within a Multi-frame Overlay shall be conveyed as a logical sequence. The order of the Overlay Frames correspond one to one with the order of the Image frames. If Image Frame Origin (60xx,0051) is present, the Overlay frames correspond one to one to the Image frames, beginning at the indicated frame number. Otherwise, the Overlay Frames correspond beginning with the first Image frame.

### Note

When an Overlay consisting of one frame is to be applied to one frame of a Multi-frame Image, it is specified with a Number of Frames in Overlay (60xx,0015) value of 1, and a frame number in Image Frame Origin (60xx,0051), because Image Frame Origin is invoked only by this Module, in which Number of Frames in Overlay (60xx,0015) is Type 1. In the absence of Number of Frames in Overlay (60xx,0015) and Image Frame Origin (60xx,0051), per Section C.9.2.1.4, a single frame overlay applies to all frames of a multi-frame image.

The Number of Frames in Overlay (60xx,0015) plus the Image Frame Origin (60xx,0051) minus 1 shall be less than or equal to the total number of frames in the Multi-frame Image.

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DICOM PS3.3 2021b - Information Object Definitions