9 The standard OPI workflow using PDF files
Placing PDF documents directly into page layouts is not fully supported by many page layout applications. Using PDF HandShake with ImageServer overcomes this limitation, by automatically creating low-res EPS "layout" files from the PDF, for placement in a page layout document. At print time, the OPI server replaces each layout image with the original high-res PDF page residing on the server.
In addition, layout images (of high-res images or PDF documents) can be placed in documents that are saved as PDF. When the resulting PDF file is printed to a HELIOS printer queue with OPI active, once again, the low-res layout images will be replaced with the corresponding high-res originals.
Using PDF HandShake together with ImageServer can also enable full composite workflow support for DeviceN/in-RIP separations, to properly preserve spot colors in DCS-2, TIFF and Photoshop images, as well as spot-colorized grayscale images.
PDF files can contain an array of objects (images, fonts, line art, etc) in a variety of color spaces (RGB, CMYK, CIE Lab, etc.). In order to successfully print a PDF file, all of the content must, at some point, be converted into the color space of the output device. PDF HandShake does include a high quality CMM (
Color Matching Module) for ColorSync ICC based color space transforms. If necessary, at print time, PDF HandShake can perform
on-the-fly color space transforms to provide proper color matched output for a given device. This
on-the-fly conversion has the advantage that the original PDF document is never modified.
In order to achieve optimal color space conversions, it is important to use the appropriate source ICC profiles (an output profile is specified for each printer queue). Many PDF documents do already include ICC profiles, and these can be used by PDF HandShake. In cases where document ICC (source) profiles are not included with a PDF file, the
Default RGB Profile and
Default CMYK Profile that have been defined in HELIOS Admin will be used. See
5 "Setting up PDF HandShake with HELIOS Admin". When printing, these default profiles can be overridden if desired by means of the
PDF HandShake Print print dialog, or via the "pdfprint" command.
When PDF HandShake is used together with ImageServer, the ImageServer
"Tagger" program can also be used to
tag (i.e. assign or change) source profiles to a PDF document or to image files. If you are not yet familiar with the "Tagger" program, you should read the respective chapter in your ImageServer manual.
The "Tagger" program is located in the "HELIOS Applications" volume in "MacOS > OPI Tools", see Fig.
32.
Fig. 32:
Starting the "Tagger" program
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Displaying tagging
information
The
File menu of the "Tagger" program contains two items that are very useful to check whether a given file has already been tagged with profile information (Fig.
33).
Fig. 33: The "Tagger" program
File menu
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The
Get Tag Info- item opens a window that lets you select the file you want to get info about. It will then be displayed in the
Tagging Information Window that is shown in Fig.
34, and you can see whether or not the file is tagged. If you choose
Open Tag Info Window from the
File menu, an empty window opens so you can drag and drop several files at the same time into that window. This is shown in Fig.
34.
Fig. 34: Entries in a "Tagging Information Window"
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If a file is listed twice (in normal and
italic representation) this indicates that the file has been tagged with both an RGB and a CMYK profile. The buttons in the information window serve to either delete (
Clear) all entries, or save them into a text file (
Save-) for further usage.
If you wish to create a new ICC info file (for automatic tagging of files), please follow the instructions given in the respective chapter of your ImageServer manual. Note that the tagging dialog includes the PDF file format (Fig.
35). Unlike "pure" images, such as TIFF or Photoshop files, PDF documents may contain several color spaces. Therefore, for the PDF file format, you always have to specify both an RGB
and a CMYK profile. Otherwise, if PDF files are tagged with one profile only, attempts to
re-tag these files later will fail.
Fig. 35: Setting up tagging instructions for PDF files
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Please remember to use the two options
Overwrite existing profiles and
Update Folder Contents very carefully, because they might destroy existing profile information.
Overwrite existing profiles will induce the OPI server to tag the profile information that is defined in this particular ICC info file to all image files or PDF documents that will later be saved in that folder, and to overwrite existing profile information - if the incoming files have any.
To tag image profile changes to PDF files, first choose
None from both the RGB
and the CMYK profile pop-up menu. Then check
Overwrite existing profiles and make new profile assignments for both the RGB
and CMYK profiles, by choosing them from the pop-up menu.
Update Folder Contents will assign the tagging information of this particular ICC info file to all files that are already located in the folder and which are not yet tagged. Be careful: depending on the number of untagged files in the folder, this could take some time.
If you check both options and save the ICC info file, all existing files and all incoming files in that folder will be re-tagged.
Both options are inactive by default.
9.2 About the handling of PDF files (OPI server)
9.2.1 Automatic layout generation
To enable the layout generation for PDF high-res files, activate the following options in HELIOS Admin:
- Create Layouts (Volumes > OPI)
- PDF OPI Layout Generation (PDF HandShake Settings)
If both options are activated, the OPI server will automatically generate layouts for all PDF files that are saved in the HELIOS server volume. The specified parameters in the
OPI Server Settings dialog will then be valid for PDF files as well, e.g. layout resolution, layout name, etc. See the respective chapter in your ImageServer manual for details.
By default, the file format of the PDF layout representations will be EPSF for composite PDF files and DCS for pre-separated PDF files.
The OPI server uses the first page of the PDF documents only to generate layouts. If you have a multi-page document and want to have layouts from several pages, you can use our "pdfcat" tool to split your document into several single-page files. Find more information in
6.1 "pdfcat".
Note: You may also use the ImageServer "opitouch" program for the layout generation of PDF documents. "opitouch" is described in the ImageServer manual.
PDF files may contain several images, illustrations and text on one page, meaning that the pages could become very complex. Depending on the
Layout Delay time you have specified in the
OPI Server Settings, and on how complex the given PDF files are, the generation of layouts can take some time (in some cases even more than a minute).
9.2.2 PDF-native OPI replacement
This new PDF HandShake functionality replaces layout images directly in the PDF document. This is done without the need to convert the PDF document into PostScript first, and then back to PDF. Thereby the PDF remains unchanged because only the images within the document are replaced. Some more features of PDF OPI resolve are:
- Transparencies are preserved
- Meta data (e.g. job tickets, XMP) are preserved
- It is fast and reliable
Note: PDF OPI resolve requires ImageServer UB to be installed and licensed on the same host.
All settings are configurable just as in an OPI printer queue:
- ICC profiles and output parameters
PDF OPI resolve utilizes specially configured "hot folders".
It can be used via command-line tools or "hot folders" to repurpose an InDesign low-resolution PDF job, so that there is no need to output an InDesign document for different needs, e.g.:
- Optimized for press
- Optimized for digital print
- Optimized as 144 dpi RGB color matched customer proof
- Optimized for archiving with JPEG2000 image compression
9.2.3 Resolving OPI comments in PDF files
PDF files can already contain OPI comments. For example, if you design a FreeHand document, import some layout images (by reference) into this document, and then print into a PostScript file, the resulting PostScript file will contain as OPI comments the references to the high-res images. The OPI comments can be preserved - depending on the Acrobat Distiller job options you define (see
A 1 "Create PDF files using Acrobat Distiller").
Whenever OPI comments are included in a PDF file, the OPI server is able to resolve these comments. That means that if you place an EPSF layout file (generated from a PDF original) into a layout application and then print your new document, image replacement will possibly be performed twice: the OPI server replaces the EPSF layout in your document with the PDF original
and replaces the layout files in the PDF document with the respective originals. An example is given in Fig.
36 below.
Note: In the PDF HandShake Acrobat plug-in and "pdfprint" program there are options to switch off OPI image replacement. See -o noopi in 8.1 "pdfprint" and OPI Settings in 8.2 "Printing PDF files using the Acrobat plug-in".
In the example illustrated below, color matching will also be performed on two different layers. All objects of "Doc1.pdf" that will not be replaced again, will be matched according to the profiles R1 and C1 - depending on the color space of the respective object. The files A and B will be matched according to the image profiles that are tagged to the high-res originals (here: profiles R2 and R3).
Fig. 36: Resolve OPI comments in PDF high-res files
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In certain situations, resolving OPI comments in PDF documents can cause problems, especially if you send your PDF documents to another production site. In that case - if the PDF document contains layout images and OPI comments pointing to the originals - make sure that you also send these originals
and all the profiles that are needed. Sometimes, it could be wiser to embed everything in the PDF file and switch off the option
Preserve OPI Comments in the Distiller (see
A 1 "Create PDF files using Acrobat Distiller").
9.2.4 Pre-separated PDF files and ImageServer
Pre-separated PDF documents are recognized by ImageServer. They are handled as follows:
- The "layout" and "pdftoeps" server command line programs generate DCS files with default (depending on the server settings) composite previews which are raster-based. In order to change the screen preview resolution, use the -R option (see 6.5 "pdftoeps"). The "layout" program creates single file DCS-style layout images while the "pdftoeps" program creates DCS-1 or DCS-2 style multi-file images. The plate file suffixes for CMYK will be .C, .M, .Y, and .K. Spot color plate files will be assigned other suffixes, namely letters so far unused in alphabetical order. The suffix does not have any relation to the name of the spot color.
- Printing separations of documents containing placed layouts of pre-separated PDF files to an OPI printer queue with image replacement is fully supported for all output devices.
Note: Composite printing of documents containing placed layouts of pre-separated PDF files to a PrintPreview queue will lead to blank picture boxes in the preview.
9.3 OPI layout images of PDF files
9.3.1 PDF shading support
PDF HandShake 2.5 has already supported PDF 1.3 shadings for composite PostScript 3 output and OPI layout images from PDF files containing PDF 1.3 shadings. PDF HandShake UB adds support for printing PDF shadings in separations.
9.3.2 Options of the "layout" program
The "layout" program (see the respective chapter in the ImageServer manual) offers some options which relate to OPI layout generation of PDF files.
-o PureWhite <boolean:None>
-o PureGrays <boolean:None>
-o PureBlack <boolean:None>
9.3.3 Attributes for "layout" options
The attributes are entered as command line options using the
layout -o Attributes=<attributes>=<value> syntax. Additional attributes are delimited by commas.
This PDF only attribute smooths the screen preview. It can be used to override the default PDF preference
AntiAlias which is described in
14 "Preferences".
This attribute lets you specify a certain page of a PDF document for the layout process.
