Table 91 – Entries in an Alternate Image Dictionary

Key

Type

Value

Image

stream

(Required) The image XObject for the alternate image.

DefaultForPrinting

boolean

(Optional) A flag indicating whether this alternate image shall be the default version to be used for printing. At most one alternate for a given base image shall be so designated. If no alternate has this entry set to true, the base image shall be used for printing by a conforming reader.

OC

dictionary

(Optional; PDF 1.5) An optional content group (see 8.11.2, "Optional Content Groups" ) or optional content membership dictionary (see 8.11.2.2, "Optional Content Membership Dictionaries" ) that facilitates the selection of which alternate image to use.