PDFlib 8 Windows COM/.NET Tutorial

10.4.2 Generating PDF/A-conforming Output
Cookbook Code samples for generating PDF/A can be found in the pdfa category of the PDFlib Cookbook.
Creating PDF/A-conforming output with PDFlib is achieved by the following means:
> PDFlib will automatically take care of several formal settings for PDF/A, such as PDF
version number and PDF/A conformance keys.
> The PDFlib client program must explicitly use certain function calls and options as
detailed in Table 10.6.
> The PDFlib client program must refrain from using certain function calls and option
settings as detailed in Table 10.7.
> Additional rules apply when importing pages from existing PDF/A-conforming documents
(see Section 10.4.3, »Importing PDF/A Documents with PDI«, page 264).
If the PDFlib client program obeys to these rules, valid PDF/A output is guaranteed. If
PDFlib detects a violation of the PDF/A creation rules it will throw an exception which
must be handled by the application. No PDF output will be created in case of an error.
Required operations for PDF/A-1b. Table 10.6 lists all operations required to generate
PDF/A-conforming output. The items apply to both PDF/A conformance levels unless
otherwise noted. Not calling one of the required functions while in PDF/A mode will
trigger an exception.
Table 10.6 Operations which must be applied for PDF/A-1 level A and B conformance
item
conformance level
output condition
(output intent)
fonts
grayscale color
RGB color
CMYK color
PDFlib function and option requirements for PDF/A conformance
The pdfa option in begin_document( ) must be set to the required PDF/A conformance level, i.e.
one of PDF/A-1a:2005 or PDF/A-1b:2005.
load_iccprofile( ) with usage=outputintent or process_pdi( ) with action=copyoutputintent
(but not both methods) must be called immediately after begin_document( ) if any of the devicedependent
colors spaces Gray, RGB, or CMYK is used in the document. If an output intent is used,
an ICC profile must be embedded (unlike PDF/X, unembedded standard output conditions are not
sufficient in PDF/A). Use the embedprofile option of load_iccprofile( ) to embed a profile for a
standard output condition.
The embedding option of load_font( ) (and other functions which accept this option) must be
true. Note that embedding is also required for the PDF core fonts. The only exception to the embedding
requirements applies to fonts which are exclusively used for invisible text (mainly useful
for OCR results. This can be controlled with the optimizeinvisible option.
Grayscale images and setcolor( ) with a gray color space can only be used if the output condition
is a grayscale, RGB, or CMYK device, or if the defaultgray option in begin_page_ext( ) has been
set.
RGB images and setcolor( ) with an RGB color space can only be used if the output condition is an
RGB device, or the defaultrgb option in begin_page_ext( ) has been set.
CMYK images and setcolor( ) with a CMYK color space can only be used if the output condition is
a CMYK device, or the defaultcmyk option in begin_page_ext( ) has been set.
Prohibited and restricted operations. Table 10.7 lists all operations which are prohibited
when generating PDF/A-conforming output. The items apply to both PDF/A conformance
levels unless otherwise noted. Calling one of the prohibited functions while
in PDF/A mode will trigger an exception. Similarly, if an imported PDF document does
not comform to the current PDF/A output level, the corresponding PDI call will fail.
10.4 PDF/A for Archiving 261