In "Screening", you set the individual screening parameters for the output.
The following parameters are interrelated:
•Type (screen system)
•Dot Shape (screen dot shape)
•Resolution (output resolution)
•Screen Ruling (frequency)
•Spot Size (screen dot size)
Additionally, the selections that can be made depend on the connected imagesetter.
The dependencies are displayed in the diagram below:
The resolution depends upon the current device parameters and the screen system selected ("Screen System" input box). The selection of the screen frequencies and dot sizes depends upon the resolution selected.
Note: The screen systems available for selection depend on the connected imagesetter. For that reason, not all of the screen systems presented are available for all constellations.
Note: The following information is applicable to the "Hybrid Screening", "Stochastic Screening" and "Satin" systems:
•"Hybrid Screening"
The frequency and the dot size are relevant for amplitude-modulated "Hybrid Screening". The "Line Frequency" and "Feature Size" list boxes are enabled.
•"Stochastic Screening":
The dot size is important for frequency-modulated "Stochastic Screening". The "Feature Size" list box is enabled and the "Line Frequency" boxes disabled.
•"Satin":
The dot size is important for the "Satin" frequency-modulated screening method. The "Feature Size" list box is enabled and the "Line Frequency" boxes disabled.
•You can also set the dot size for "IS Classic" like for "Hybrid Screening" if the "Hybrid Screening" license option is enabled.
"Dot Shape" list box
In this list box, you set the screen dot shape that will be used for the screen system you selected.
"Resolution" parameter
This is where you set the imagesetter resolution (in dpi or pixels/cm) for the screen that will be created.
"Frequency" parameter
In these list boxes, you can select one of the screen frequencies (in lines/inch or lines/cm) that are presented for the selected screen system. There is a special frequency box for "Document controlled screening" where you can type in a screen frequency.
"Feature Size" parameter
The feature size (dot size) is relevant for frequency-modulated screens (see note on this above).
Note: The "Feature Size" parameter is not a calibration parameter. This means that calibration data records cannot be differentiated solely on the basis of different dot sizes. This affects calibration of the "Hybrid Screening" and "IS Classic" screen systems if these are selected in output sequences with different dot sizes but otherwise the same parameters. You must create different calibration groups for linearization and for process calibration if you are going to use different calibrations whose only difference is their dot sizes. These calibration groups must contain the calibration data records that are required for the various dot sizes.
"Objectscreening from PDF Tools" group
The "Screening Selector" tool in the "HEIDELBERG PDF Toolbox" Acrobat plug-in lets you assign different screen settings to single objects within a PDF document. The options in this group define how such object screening parameters will be handled during output.
"Ignore Object screening information"
When you enable this option and a document has objects with different screen settings, this screening information is ignored, and the screen settings defined in the sequence are used.
"Use Object Screening Information"
The object screen settings set up with the Screening Selector are applied when you enable this option.
"Step and Repeat Settings" group
"Optimize Step and Repeat" option
"Step and Repeat" is a technique that copies and positions at the same time.
This option is designed for print jobs that have several identical pages placed on one sheet (copies). The aim of step-and-repeat optimization is to interpret each of the objects that are repeated just once to shorten processing time.
You enable the function with this option. Then each of the objects that are repeated in jobs that have copies is interpreted just once.
"Synchronize screening for each page" option
When this option is enabled, the screen is synchronized at every multiple object (on every page). This option is required for packaging printing and for security printing (e.g. bank notes). The screen transitions can be seen in the printed result if the single pages abut each other.
The screen always starts at the top left corner of the sheet if the "Synchronize screening for each page" option is disabled, and there is no renewed synchronization within the sheet. This is the same as processing without step-and-repeat optimization.
Step-and-repeat optimization is not applied even if the option is enabled if you have one of the following conditions:
•The multiple pages are rotated and rotation is not a multiple of 90° (e.g. 1° to compensate errors during cutting).
•The pages are split for proofing because the "Split Document" option is enabled.
In "Angle Substitution" you can modify the screen angle settings of the various colors for amplitude-modulated screen systems.
With the help of the angle substitution functionality, you can assign new screen angles to the process colors (cyan, magenta, yellow and black) and to spot colors. In other words, the angles set in the job documents are changed to new angles that you define in this section when they are output.
The colors currently assigned to the angles display to the right of the color list boxes. A default system angle is assigned to each process color:
Color | System Angle |
Cyan | 165° |
Magenta | 45° |
Yellow | 0° |
Black | 105° |
Assign angles
Each process color is assigned "Use for [color] the systemangle from". Beside each item, there is a list box displaying this color by default as well. The system angle relating to the selected color displays to the right of the list box. If you now assign a different color in the list box, the system angle of the selected color is assigned to the color.
Example: In "Use for Cyan the systemangle from", "Magenta" with the system angle of 45° is selected in the list box. This angle displays to the right of the list box. Then the angle of 45° is assigned to "Cyan" instead of the system angle of 165°. Because the same screen angle is now set for cyan and magenta, you must also modify the screen angle for magenta so that a different angle is assigned to each process color.
"The selected angles will be used cyclically for spot colors" options
You can also assign different screen angles to spot colors with this function. The idea behind this is for you to be able to assign as many as four screen angles, depending on the number of spot colors you have. The enabled angles are then assigned cyclically to the spot colors.
The check boxes show the system angles set in the "Use for [color] the systemangle from" rows. In other words, if the system angles are changed, the angles displayed also change accordingly. The order of the check boxes depicts the order of the "Use for [color] the systemangle from" rows: Cyan, Magenta, Yellow, Black.
If you enable just one check box, all the spot colors in the documents will be assigned to this screen angle. If you enable several check boxes, the spot colors will be assigned in turn to the enabled screen angles. Spot colors will be assigned cyclically to the screen angles if there are more spot colors than enabled screen angles. For example, if you have five spot colors and all check boxes are enabled, the angles for cyan, magenta, yellow and black are assigned to the first four spot colors. The angle for "Cyan" is assigned again to the fifth spot color etc.
Note: Spot colors which only differ by the ending in the name are treated as one color. Example: No difference is made between the colors "PANTONE 165 C" (coated) and "PANTONE 165 U" (uncoated) and they are assigned to the same angle.
Note: Take note of the following items when you use the 'assign spot color to screen angle' function:
•The names of the spot colors are irrelevant in the assignment of angles. The angles are assigned if the spot colors occur in the document.
•Angle substitution must not be set for process colors if duotone and tritone images will be processed together with process colors. This means that they must stay assigned to their default system angles.
•Only the cyan and magenta angles may be used for spot colors if duotone and tritone images that have black are to be processed!
•Do not use any fine screens in conjunction with the spot color-to-angle assignment. This can cause problems with yellow and black.
•Process calibration may not be correct if you use the 'assign spot color to angle' function.
•The angle defaults for spot colors are also affected by the assignment of angles. The default angle for spot colors is 45° (magenta).
"Frequencies from DTP Applications" group
"Override Frequencies from Document" option
The screen frequency in the edited document (set in the DTP application) is overwritten by the screen frequency set in the output sequence.
"Use Frequencies from Document" option
The screen frequency in the edited document (set in the DTP application) is used.
Generally, it is advisable to use the screen frequency of the output sequence as this gives you a reliable output.
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