PDFlib 8 Windows COM/.NET Tutorial

Table 10.12 PDF/A color strategies
output intent
color spaces which can be used in the document
CIELab 1 ICCBased Grayscale 2 RGB 2 CMYK 2
none yes yes – – –
Grayscale ICC profile yes yes yes – –
RGB ICC profile, e.g. sRGB yes yes yes yes –
CMYK ICC profile yes yes yes – yes
1. LZW-compressed TIFF images with CIELab color will be converted to RGB.
2. Device color space without any ICC profile
In addition to the color spaces listed in Table 10.12, spot colors can be used subject to the
corresponding alternate color space. Since PDFlib uses CIELab as the alternate color
space for the builtin HKS and PANTONE spot colors, these can always be used with PDF/
A. For custom spot colors the alternate color space must be chosen so that it is compatible
with the PDF/A output intent.
Note More information on PDF/A and color spaces can be found in Technical Note 0002 of the PDF/A
Competence Center at www.pdfa.org.
10.4.5 XMP Document Metadata for PDF/A
PDF/A-1 heavily relies on the XMP format for embedding metadata in PDF documents.
ISO 19005-1 refers to the XMP 2004 specification 1 ; older or newer versions of the XMP
specification are not supported. PDF/A-1 supports two kinds of document-level metadata:
a set of well-known metadata schemas called predefined schemas, and custom extension
schemas. PDFlib will automatically create the required PDF/A conformance entries
in the XMP as well as several common entries (e.g. CreationDate).
User-generated document metadata can be supplied with the metadata option of
begin/end_document( ). In PDF/A mode PDFlib verifies whether user-supplied XMP document
metadata conforms to the PDF/A requirements. There are no PDF/A requirements
for component-level metadata (e.g. page or image).
XMP metadata from imported PDF documents can be fetched from the input PDF via
the pCOS path /Root/Metadata.
Cookbook A full code sample can be found in the Cookbook topic interchange/import_xmp_from_pdf.
Predefined XMP schemas. PDF/A-1 supports all schemas in XMP 2004. These are called
predefined schemas, and are listed in Table 10.13 along with their namespace URI and
the preferred namespace prefix. Only those properties of predefined schemas must be
used which are listed in XMP 2004. A full list of all properties in the predefined XMP
schemas for PDF/A-1 is available from the PDF/A Competence Center.
XMP extension schemas. If your metadata requirements are not covered by the predefined
schemas you can define an XMP extension schema. PDF/A-1 describes an extension
mechanism which must be used when custom schemas are to be embedded in a
PDF/A document. Table 10.14 summarizes the schemas which must be used for describing
one or more extension schemas, along with their namespace URI and the required
1. See www.aiim.org/documents/standards/xmpspecification.pdf
266 Chapter 10: PDF Versions and Standards (Edition for COM, .NET, and REALbasic)