PDF/X
Under PDF / X standards different to the International Organization for Standardization are summarized. These describe the properties of printing templates as PDF files, to allow the template faithful transmission of the data from prepress to the actual pressure. So PDF/X-1a describes the color rendition in the CMYK color model, while PDF/X-3 extends this to the RGB color space.
Properties
Through PDF / X is a subset of the Portable Document Format ( PDF) is standardized, which meets the requirements of printing technology to the corresponding print template. There are both PDF prohibited items which may affect the predictability of the print result, as well as those that do not can be useful print ( z, video and audio). In addition, precise information is required, which are necessary for the printer, such as cropping, color and fonts used. Aim of the standards is to avoid various problems in the exchange of files from desktop publishing and graphics software with the printer or at least minimize.
Compliance with the requirements can be checked by means of the so-called preflight during the entire pre-press. This gives the print result is considerably more reliable the desired layout. Thus, preferably, the Media Standard Print PDF / X as a data format for proofs, it is based on the 12647 enshrined in ISO Process Standard Offset (PSO ).
Do not be defined dependent on the specific printing process quality requirements. For example, the demands of newspaper printing differ both from commercial printing as well as high-quality images from the pressure. Much of the layout and some word processing programs provide a direct export of PDF / X files. Alternatively, can first be printed in PostScript, after which the data using conversion programs such as Adobe Acrobat or GhostScript to PDF or PDF / X can convert.
When creating the templates different aspects of PDF / X will not be considered:
- The appropriate procedure for resolution of full-tone, halftone or line images;
- With lossy-compressed JPEG images arise sometimes a clearly visible artifacts;
- To thin hairlines and increase printing " break away ", they are then only with the magnifier or not at all to see;
- In the PDF file a missing font is replaced by another, often Courier;
- Black letters or lines are defined so that they are built in pressure three - or even four-color, see the CMYK color model.
Some of these problems is with so-called profiles are contained in a " list of issues " mentioned by some programs already in the PDF creation.
PDF / X defined rules focusing on the following problem areas:
- All fonts used must be at least included as subgroups, cf formats of PostScript fonts.
Color rendering
Color must meet certain requirements. Support for Lab and ICC-based color in PDF/X-3 allows for some " media neutrality ", that is, the same document can theoretically be issued under different pressure conditions with the best possible color representation. PDF/X-1 is more widespread in America. PDF/X-3 is mainly propagated in Europe.
- Clearly interpretable color X -1a: only CMYK and spot colors
- X-3: in addition to CMYK and spot colors are RGB, Lab and ICC-based color spaces additionally allowed
Other information
In addition, there are other properties, which include the following:
- Completeness of data and information for print
- Exclusion of incidental pressure results
- Page size of the trimmed page ( TrimBox ) and necessary bleeds ( BleedBox )
- Bleed and trim size must be defined ( BleedBox, TrimBox )
- Not use LZW compression
- Notes and comments are allowed only outside the printed area
- All images must be included ( no OPI functions, but there are PDF/X-2 )
- No encryption ( "Security" ), as this is a hindrance for the files to be printed by other
- Trapping: It must be specified whether the PDF / X file was already crowded by the recipient or, if appropriate, must be crowded
- Creation or last modification date and document title and details on the production program must be available
- No page description operators that are not defined in the PD format
- Prohibition of embedded PostScript
- Exclusion of Curves (a "transfer functions").
- No transparencies
In 2003, PDF/X-3 as ISO 15930-6 in a revised version - as PDF/X-3: 2003 called - published wherein substantially only minor formal changes were made. With the revised version are now, however, all PDF/X-1a always valid PDF/X-3.
Overview of standards
Meanwhile PDF / X exists in a variety of variants that are identified by an appended number and a year specification. For each variant, a corresponding version of the ISO 15930 exists.
The standard ISO 15929 describes the guidelines and principles by which the various parts of ISO 15930 are being developed:
- ISO 15930-1: PDF/X-1a: 2001 limited based on PDF 1.3 color of CMYK and spot colors.
- ISO 15930-2: the originally planned version of PDF/X-2 has never been released (see Standard Part -5).
- ISO 15930-3: PDF/X-3: 2002 expanded on the basis of the PDF 1.3 color-calibrated data exchange in addition to CMYK and spot colors to other color spaces such as RGB and Lab.
- ISO 15930-4: PDF/X-1a: 2003 update based on PDF 1.4, PDF/X-1a 2001 First of all CMYK and spot colors are supported in any combination..
- ISO 15930-5: PDF/X-2: 2003 supports based on PDF 1.4, in addition to the embedded page content externally referenced page elements and thus enables OPI -like workflow.
- ISO 15930-6: PDF/X-3: 2003 based on PDF 1.4 updated version of PDF/X-3: 2002.
- ISO 15930-7: PDF/X-4 and PDF/X-4p based on PDF 1.6. Are all required elements in the file, it is called PDF/X-4. Where reference is made to an external color profile, the variant PDF/X-4p is called. Color management, CMYK, RGB, Grayscale and spot colors are supported. In addition, PDF transparencies and other optional content such as JPEG2000, 16-bit image data and OpenType fonts are allowed.
- ISO 15930-8: PDF/X-5 is based on PDF 1.6 and supports both embedded and externally referenced elements. In addition to the options as in PDF/X-4 can also multi-channel ICC profiles are used.