"Generation of inspection data" Option

Prerequisite: An Inline sheet inspection system such as HEIDLBERG Prinect Inspection Control 4 must be available on the press in order for this option to display in an ImpositionOutput sequence template, and the respective license must be enabled. In addition, any additional software components that may be required must be installed on the press and on the Prinect server. Prinect applications "Inspection Toolbox" and "PDF Toolbox" may also be required for the various inspection procedures.

An inline sheet inspection system enables continuous quality control of color reproduction on the press during printing. To do this, the colors of the press sheets are continuously measured during printing using a camera in the inspection system, and the measured values are compared with a digital reference image. The inspection system uses two files for this comparison: a "reference image" and an "inspection level file." The inspection system requires these files in the PNG image format.

This means the reference image represents the "ideal reference," i.e., the desired target state that the printed sheets should match as close as possible, which is verified by the camera measurement. Any deviations found are used for automatic ink zone readjustment during printing. The measured deviations are also transferred to the Prinect Customer Portal as "reports" and logged there in the ‘Inspection’ view of the "Insights" app.

The inspection level file defines the test area and the test accuracy with which the comparison between the measured press sheet and the reference image is performed. Different accuracy levels known as "inspection levels" for the check can be defined for a press sheet as a whole or for different areas of the press sheet,

​•​If only one inspection level is to be defined for the entire press sheet, this is set in the ImposePDF sequence.

​•​If multiple inspection levels are to be defined for different sheet areas, the inspection level file must be created manually using the Coating Editor in PDF Toolbox.

The Prinect workflow supports five inspection levels, with level 1 representing the highest and level 5 the lowest inspection accuracy.

The inspection level files can be generated automatically in the Prinect prepress system at the following points:

​•​The ImposePDF sequence generates the inspection level files in PDF format. These PDF files are converted to PNG image data shortly before offset printing output when running through the SheetfedPrinting sequence.

​•​The ImpositionOutput sequence generates the inspection level files in PNG format.

The PNG inspection level files are transferred to the inspection system via the network connection between Prinect server and Press Center.

Generating reference images and inspection level files

The reference images and inspection level files are generated at different points in the print shop workflow. A distinction must be made here between a Prinect Production configuration with Prinect Prepress Manager as the prepress system and a "mixed" configuration with a third-party prepress system and Prinect Pressroom Manager.

Creating reference images

Reference images are generated in the Prinect prepress system – in accordance with the inspection level files – either with ImposePDF, initially as PDF files, and then converted to PNG files shortly before offset printing output when running through the SheetfedPrinting sequence, or directly as PNG files with an ImpositionOutput sequence.

Depending on the workflow configuration, the reference image files are generated at different locations:

​•​In a Prinect Production configuration, reference images are generated from the sheet PDF files of the print jobs processed with Prinect Prepress.

​•​In a Prinect Pressroom Manager configuration with a third-party prepress system, the prepress system generates a reference sheet in composite PDF format for each press sheet and transfers it to a specific hot folder in Pressroom Manager. These PDF files are converted to PNG image data by the SheetfedPrinting sequence if the "Generation of inspection data" option is enabled there. See "Generation of inspection data" option.

Generating Inspection Level Files

Inspection level files define both the inspection area and the accuracy of the inspection that the inspection system performs on the press sheets. The inspection accuracy is defined in one of 5 "inspection levels." In the inspection level file, the inspection levels are represented by different shades of gray. If inspection areas with different inspection levels are defined manually using the Coating Editor in Prinect PDF Toolbox, a separate, additional color separation is generated for each inspection level and added to the PDF sheet file. If the inspection level files are generated automatically using the ImposePDF sequence, the inspection accuracy is defined for a complete sheet, and each sheet is assigned a single inspection level. If the inspection areas are defined manually, different inspection levels are assigned to individual areas of the sheet content. The different inspection levels define how accurately the inspection system is to check the respective areas. Inspection level files are generated in the following locations:

​•​In a Prinect Production configuration, the inspection level files are prepared in the ImpositionOutput sequence by adding the necessary additional inspection level color separations to the processed PDF files. For this purpose, the "Generation of inspection data" option must be enabled in the ImpositionOutput sequence. When the SheetfedPrinting sequence is running , i.e., immediately before print output, the inspection level files are converted to PNG image format. For this purpose, the "Generation of inspection data" option must be enabled in the SheetfedPrinting sequence. See "Generation of inspection data" option.

​•​In a Prinect Pressroom Manager configuration with a third-party prepress system, the prepress system generates an inspection level file in PDF format for each printed sheet and submits it to Pressroom Manager. See also Import of inspection data from an external prepress system. These PDF files are converted to the PNG image format by the SheetfedPrinting sequence if the "Generation of inspection data" option is enabled there.

​•​In addition, specific areas with different inspection levels can be defined manually in the PDF sheet files. This can be helpful if the press sheet contains "critical" objects that need to be checked particularly thoroughly, while other areas of the sheet need to be checked less thoroughly to prevent unnecessary false positives. The Coating Editor in PDF Toolbox can be used to create individual inspection level areas. Basically, a separate color separation is created for each defined inspection level and added to the PDF documents. In these color separations, the defined inspection level areas are shown as gray areas. Each inspection level is assigned a specific gray level density (in %). See also Manual definition of inspection areas with the Coating Editor in PDF Toolbox.

Generating Inspection Level Files in Prinect Prepress Manager

If the "Generation of inspection data" option is enabled in an ImpositionOutput sequence and an option other than "Off"’ is selected in the "Generation of inspection level" selection list, the following data is automatically generated for the PDF sheet files processed with this ImpositionOutput sequence:

​•​The processed PDF sheet files are enhanced with additional color separations for inspection data. Depending on the selection in the "Create Inspection Level" drop-down list, corresponding color separations are added to the processed PDF files. See "Generation of inspection level" list box.

​•​A reference image file (in png format) is automatically generated for each processed PDF sheet file.

"Generation of inspection level" list box

You can choose from the following options in the "Generation of inspection level" list box:

​•​"Off": No inspection level file is created, even if the job PDF file contains inspection level data.

​•​"from PDF-File": If inspection levels are defined in the job PDF file, e.g., by manually creating inspection level areas with the Coating Editor of Prinect PDF Toolbox, this data is used for the inspection level file. See Manual definition of inspection areas with the Coating Editor in PDF Toolbox. An empty inspection level file (.png) is created if no inspection levels are defined.

​•​"Level 1 automatic" to "Level 5 automatic": Color separations are automatically created for the individual inspection levels. If the PDF files already contain manually defined inspection level information (or corresponding color separations), this information is offset against the information level color separations generated by the ImpositionOutput sequence so that all defined inspection levels are taken into account in the result. See Manual definition of inspection areas with the Coating Editor in PDF Toolbox

Note: Please note that in versioned jobs, inspection level data is only generated in the master version. This means that the inspection level data generated for the master version is applied equally to all versions. You should take this into account when defining the inspection areas.

Example: Different versions differ in terms of language. If text placed in the layout is to be checked more thoroughly by the inspection system than the surrounding area, an inspection area should be defined around the sheet area in which the text is located. This area should be large enough to ensure that the text is also covered in another language that requires more space. This inspection area should be assigned an appropriately precise inspection level.

Manual definition of inspection areas with the Coating Editor in PDF Toolbox

If the inspection level files are to be defined individually, the Coating Editor of Prinect PDF Toolbox offers the option of defining or editing the PDF inspection level files and assigning different inspection levels to individual areas (surfaces) of the press sheets. To do this, open the respective PDF sheet file in the Coating Editor of Prinect PDF Toolbox. There you can manually add special gray level objects to the press sheet as "Varnish objects". Assign one of the inspection levels 1–5 to each of these objects. Each inspection level is represented by its own gray level: the more thorough the inspection is to be (maximum inspection level 1), the darker the assigned gray level (the higher the gray density). The individual inspection levels correspond to the following gray densities:

This makes it possible to have certain areas of the printed sheet inspected particularly thoroughly, while other areas are inspected less thoroughly. A separate color separation is created for each defined inspection level and added to the PDF documents. You can find more details about this in the Online Help for PDF Toolbox.

Editing the inspection level files with a SheetfedPrinting sequence

If the PDF files extended with the inspection data separations are processed with a SheetfedPrinting sequence in which the "Generation of inspection file" option is enabled, the SheetfedPrinting sequence combines all color separations into a composite PDF file and generates an inspection level file (in png format). See "Generation of inspection data" option.

Submitting the reference files and the inspection level files to the inspection system

The reference files and the inspection level files are transferred to the inspection system via the network connection between Prinect server and Press Center.