Represents the "OPI" entry of the image dictionary object.

It is an optional entry defined as part of the PDF 1.2 specification. It was deprecated in PDF 2.0.

It contains an OpiVersionElement.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 89, page 208.

Adobe Supplement to the ISO 32000, BaseVersion: 1.7, ExtensionLevel: 3; Table: 4.39, page 27.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 87, page 257.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 146, page 349.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 144, page 418.

The OPI dictionary holds Open Prepress Interface information for the image. It carries metadata used by OPI servers to substitute a high-resolution version of the image at output time.

OPI workflows use low-resolution proxies in the PDF for layout and proofing, replacing them with production-quality images only during final output. The OPI dictionary provides the information needed to perform that substitution.