Represents the "Image" entry of the alternate image dictionary object.

It is a required entry defined as part of the PDF 1.0 specification.

It contains an ImageXObjectElement.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 91, page 212.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 89, page 261.