11 PDF-native OPI workflow

HELIOS ImageServer is well-known as a reliable, colortrue and fast OPI workflow solution. For more information about OPI workflows see the ImageServer manual. All classic OPI workflows use the print function of page layout applications (e.g. InDesign) to produce PostScript output with OPI references. These OPI references are placeholders for high-resolution images. To obtain a full-resolution document, e.g. for the generation of a printing plate, the OPI references within the PostScript output are resolved, i.e. replaced with high-resolution images. Then this resolved PostScript output is used for further processing with a trapping, imposition or rasterizing solution.

The basic idea behind PDF HandShake’s new PDF-native OPI workflow is to use the InDesign or QuarkXPress ¹ PDF export function to produce PDF output with OPI references instead of PostScript output with OPI references. As mentioned above, to obtain a full-resolution document, the OPI references within the exported PDF document are resolved, i.e. replaced with high-resolution images, and the result is a new PDF document containing the high-resolution images. The command line utility “pdfresolve” (see 6.7 “pdfresolve”) provides this new OPI image replacement functionality for PDF documents. This functionality can also be used by means of a hot folder utilizing the Script Server example script “pdfresolve.pl”.

For more information on Script Server and the example script “pdfresolve.pl” see the ImageServer manual. This workflow needs neither PostScript documents nor conversions from PDF to PostScript or vice versa. The development of “pdfresolve” follows the current trend in workflow design to replace PostScript with PDF.

One major benefit of using PDF instead of PostScript is that it offers many features that can be expressed in PDF only but not in PostScript. In a classic PostScript based OPI workflow, much valuable information like transparency, ICC profiles, PDF/X output intents, metadata, and trapping information cannot be embedded within the document file. It is a difficult and nearly impossible task to store and maintain this information elsewhere, and once this information is lost somewhere within the workflow, it is often gone for good. Another major advantage of PDF over PostScript is that PDF viewing applications are available for many platforms whereas viewing PostScript accurately enough for prepress needs is a sophisticated task which involves high software costs.

11.1 Appropriate file formats for PDF-native OPI

You can place both high-resolution and layout images. When generating layout images via ImageServer, you can choose between EPSF and TIFF layouts. It is strongly recommended not to use high-resolution images and to generate TIFF only layouts in a PDF-native OPI workflow. You can force the recommended generation of TIFF layouts by copying the high-resolution images to a folder in a HELIOS volume with automatic layout generation enabled and using the “%t” folder naming option (see the chapter “Defining folder-specific OPI settings” in the HELIOS ImageServer manual.

What are the benefits of placing layouts instead of high-resolution images? First of all, layouts are nearly always much smaller than high-resolution images, making production possible on a limited bandwidth network or making production substantially faster. This is also the main reason why OPI is used in the first place.

What are the benefits of placing TIFF layouts rather than EPSF layouts? First of all, the current versions of InDesign and QuarkXPress (up to version 9) do not embed the Mac file ID of high-resolution images in the exported PDF documents when using EPSF layouts. Furthermore, ImageServer generates TIFF and EPSF layouts from high-resolution images with clipping paths while preserving these clipping paths, but e.g. InDesign copies the clipping path to the exported PDF documents only if TIFF layouts are used. “pdfresolve” does not insert clipping paths during OPI image replacement either. Hence clipping paths are lost within the PDF-native OPI workflow when using EPSF layouts.

The preference PDFNativeWorkflow (see 13.1 “Global PDF preferences”) enforces the generation of PDF-native workflow compatible layout images. So vector-based EPS images will lead to EPS layout images, even if TIFF layout images are supposed to be generated.

11.2 Export PDF

11.2.1 InDesign

When you have loaded a document in InDesign and want to export it as PDF for a PDF-native OPI workflow, you have to specify certain options in the “Export PDF” options dialog.

If you want to use the transparency features, which include drop shadow and feather effects, you must select Acrobat 5 (PDF 1.4) or higher from the Compatibility pop-up menu (Fig. 11.1) in the “General” settings section of the “Export Adobe PDF” options dialog. Prior versions of PDF do not support transparencies.

Fig. 11.1: InDesign – Export PDF compatibility

Note:: Make sure to activate the option Crop Image Data to Frames in the “Compression” settings section.

If you use TIFF layout files only, as recommended, you must check the Omit for OPI checkbox for Bitmap images in the “Advanced” settings section of the Export PDF options dialog (Fig. 11.2):

Fig. 11.2: InDesign – Export omit bitmap images

If you want to use EPSF layouts despite their disadvantages, you must check the EPS checkbox here, too.

11.2.2 QuarkXPress (up to version 9)

First of all, it is recommended to activate the Direct to PDF option in the QuarkXPress “PDF Workflow” preferences (Fig. 11.3).

Fig. 11.3: QuarkXPress – Preferences

If you want to export a document as PDF for a PDF-native OPI workflow, you have to specify certain options in the “Export as PDF” dialog.

For using the transparency features, which include drop shadow and feather effects, you must select Export Transparency Natively in the “QuarkXPress Objects” section (Fig. 11.4).

Fig. 11.4: QuarkXPress – PDF export options

If you use TIFF layout files only, as recommended, you must leave the Include Images checkbox unchecked in the “TIFF Options” section (Fig. 11.5):

Fig. 11.5: QuarkXPress – Do not include images

11.3 Configure “pdfresolve” via printer queue settings

By default, “pdfresolve” adopts all of its image replacement options from a specified printer queue. Additional command line options override printer queue settings. Printer queue settings can be edited using HELIOS Admin, but two “pdfresolve” options can only be specified via the command line, they cannot be specified in HELIOS Admin. These are the TagReplacedImages option and the options to compress replaced images with JPEG 2000 compression format. For more information on the command line options of “pdfresolve” please refer to 6.7 “pdfresolve”. Here is a short overview of the TagReplacedImages option:

TagReplacedImages	FALSE	TRUE
No printer profile specified	No color matching, no tagging of replaced images	No color matching, tagging replaced images with source image profiles
Printer profile specified	Color matching active, no tagging of replaced images	Color matching active, tagging replaced images with printer or proof profiles

Using “pdfresolve” with settings of different printer queues allows easy generation of PDF output documents for a broad range of applications, from a single PDF document exported by InDesign or QuarkXPress:

11.3.1 Downsampling and output compression

In a PDF-native OPI workflow with large high-resolution images it is advantageous to specify downsampling and compression options for the used printer queue. File sizes of resolved PDF documents can be reduced by 50% or more, to substantially shorten printing and other document processing times. These options can easily be specified in HELIOS Admin (Fig. 11.6):

Fig. 11.6: HELIOS Admin – Downsampling and compression

: In the HELIOS Admin printer queue settings select the OPI tab and from the Downsampling pop-up menu choose a resolution (in dpi) which will be applied to objects in the PDF document that exceed the specified value.

: Likewise, specify an output compression method from the Bitmap, Monochrome, and Color pop-up menus.

It is recommended to choose a lossless compression type such as “ZIP” or “CCITT Group 4”.

11.3.2 Hot folder setup

Please refer to the HELIOS ImageServer manual for how to set up the Script Server and how to use the example script “pdfresolve.pl” to set up a PDF-native OPI hot folder.

11.4 Limitations

Raster images and PDF documents are supported as high-resolution images only, object-based EPSF documents are not supported
Using EPSF layouts leads to reduced high-resolution image file search functionality and loss of clipping paths and transparency, see above
Ultimately, all PDF documents need to be rastered, e.g. for the generation of a printing plate. All current RIP solutions can rasterize PDF documents with transparencies, alternatively Adobe Acrobat Professional can be used to print and flatten PDF documents with transparencies

11.5 Remote PDF-native OPI workflows

The basic concept of a remote PDF-native OPI workflow is:

Generate TIFF layout images from high-resolution images on a server system running ImageServer and PDF HandShake
Transfer the layout images only to the designers, e.g. via Internet and HELIOS WebShare
The designers place these layout images in InDesign documents and export the document as PDF, with Omit for OPI selected
The designers transfer the exported PDF documents back to the server system, e.g. via Internet using HELIOS WebShare
The exported PDF documents are resolved via PDF-native OPI “hot folders” for different applications, e.g. for offset printing plate generation or website publishing

¹ QuarkXPress 3-9

HELIOS Manuals September 10, 2020