C. Source image sequence

If an Image is identified to be a Derived image (see C. Image Type), Source Image Sequence (0008,2112) is an optional list of Referenced SOP Class UID (0008,1150)/ Referenced SOP Instance UID (0008,1150) pairs that identify the source images used to create the Derived image. It may be used whether or not there is a description of the way the image was derived in Derivation Description (0008,2111) or Derivation Code Sequence (0008,9215).

Note: Multiple Items may be present within Source Image Sequence (0008,2112), in which case either:

a) those images were combined to make the derived image (e.g. multiple source images to make an MPR or MIP), or

b) each of the items represents a step in the successive derivation of an image (e.g. when an image has had successive lossy compression steps applied to it),

c) some combination of the above.

The Purpose of Reference Code Sequence (0040,A170) and the Attributes within the referenced images themselves may be used to determine the history of the derivation, which is not otherwise explicitly specified.