ZePrA’s Spot Color module is the most accurate method for converting spot colors in PDF files to CMYK, RGB or to Multicolor color spaces. If a spot color license has been loaded, the function will be available in ZePrA. The Spot Color module is available standard as part of ZePrA XXL or and add-on module.

config-spot-color

Spot Color Conversion Settings

The Spot Color module can be obtained:

  • Part of ZePrA XXL, including Multicolor license
  • as a chargeable additional module for ZePrA
  • as part of the chargeable additional Multicolor module

Follow the instructions to achieve the best possible printing results:

  1. Create a spot color library. For best results, try to match and measure color values of spot colors as closely as possible based on either the printing process or a proofer, or based on the requirements of the customers. This will allow ZePrA to automatically color convert spot colors in PDF files to the target color space. The spot color libraries to be created in ZePrA contain fundamental descriptions of the spot colors, e.g. measured values of the solid tone and gradations, measurements on white and black and information as to whether they are non-printing channels, such as cutting marks, register marks or the like. Read more about this under Global Settings/Spot Colors.
  2. Apply the spot color libraries in the desired configuration to the PDF files. In the Configuration/Spot Color dialog, specify how spot colors are to be converted to the target color space. All configurations access these fundamental descriptions in the Spot Color Libraries to determine the necessary Lab or spectral values.

Converting Spot colors in pixel based formats: it is possible to convert spot colors in image files (ZePrA supports TIFF, PSD and PSB pixel formats). To do so, create the spot colors as alpha channels and with the spot color attribute.  

Without the Spot Color module, the alternate color space colors indicated in the PDF file are used for converting spot colors to the target color space.

User Defined Spot Colors

Retaining user defined colors is critical to print production. This is required in packaging printing, for example, when areas for punch marks, Braille, varnish, folding marks, trim marks, can all be retained.

Note: In many cases, standard conversion without using a custom spot color library does not result in sufficiently good rendering of the spot color, nor does it produce a substitute process color that prints well.

Converting Spot Colors

Under Define Configurations/Spot Colors spot-color objects can be converted into, for example, CMYK objects if the target profile is a CMYK profile.

There are three options to process spot colors:

  1. Convert Spot Colors option if spot colors are not wanted in the final print job.
  2. Don’t convert Spot Colors option is selected, all spot-color objects remain unchanged. If necessary, use the Gradations function to make additional tone value corrections to spot-color gradients.
  3. Convert with Alternate Color Space and Tint Transform for a lower quality conversion, similar to what Acrobat would do.

The details of what then happens are largely dependent on whether or not you have activated the Spot Color module.

Convert to Target

Under Define Configurations/Convert Spot Colors to Target Color Space, spot-color objects are converted into CMYK objects if the target profile is a CMYK profile. Use the Convert Spot Colors to Target Color Space option if spot colors are not wanted in the final print job.

If the Convert Spot Colors to Target Color Space option is not activated, all spot-color objects remain unchanged. If necessary, use the Gradations function to make additional tone value corrections to spot-color gradients.

Spot Color Libraries

Select the spot color library or multiple libraries that should primarily be used to perform conversion. The selection of the Spot color libraries in ZePrA available by clicking on the button located to the right of the selected library.

choosing_spot_libraries

Preferred Spot Color Libraries: Select a single or multiple spot color libraries. The option to Include other Libraries is also available. Automatically using Include all Libraries may not be beneficial since it is possible that a spot color from a library could be automatically selected that does not match the target printer’s capabilities.

Example: If one library in the Spot Color Library contains a spot color printed on OPP foil but the target profile was printed on paper, this would not be a match. In these cases, manually select those libraries that fit the printer’s requirements is recommended.

Prioritize Spot Color Libraries

The Move up and Move down buttons prioritizes the selected libraries. The libraries at the top of the list have priority in the order that has been set.

Independent features from ZePrA libraries 

Embedded CxF Data: automatic use of any available CxF/X-4 spectral data for spot colors in PDF files. CxF/X-4 has been an ISO standard since 2015 and has been designed to define spot colors by measuring and storing spectral information of ink solids and tints, on substrate and process black. This spectral definition allows color management systems like ZePrA to better proof and reproduce spot colors.

spot-color-prefered-libr

Lab Values from PDF Alternate Colors: Utilizes the alternate color space instead of using a library. Later versions of Adobe InDesign saves Lab alternate color space values in the PDF instead of CMYK. When spot colors do not have a CxF value or is not available in a spot color library, the Lab alternate value from the PDF can be used and processed with the advanced ZePrA calculation methods.

 

Note: When the alternate color space in the PDF is not Lab but e.g. CMYK, ZePrA will not use the color and regard it as undefined.

Undefined Spot Colors

Specify what is to be done with spot colors that are not listed in the color libraries and the table below.

Convert using Alternate Color Space from PDF: If spot colors are always to be resolved and converted with the possibly inaccurate PDF alternate color space if necessary, then select

Keep Spot Color: All spot colors are retained

Move File to Error Folder: An error message will appear in ZePrA’s Overview window for the respective job, indicating the first undefined spot color. The file can be located in the Error folder of the specific queue.

Note: Files may also contain multiple undefined spot colors, even if only one is listed.

Calculation Method

The Calculation Method selects the way in which ZePrA converts spot colors, combinations of spot colors and process colors, or multiple spot colors to the target color space.

spot-color-choose-method

Choose a Method for Conversion

Four options are available:

Precise Match – Proofing to reproduce spot colors on a proofing printer as precisely as possible. This method is not meant to be used in production as it may use all process colors to achieve the closest match (based on DeltaE 2000). The full tone is calculated that results in the lowest possible DeltaE 2000 value. No channel minimizing and print optimization is applied.

Visual Match – Utilize More Channels: The visually best conversion with high colorimetric accuracy and with good printability. Solid tones and gradients of spot colors are converted with a minimum of channels and are still colorimetrically accurate. Spot colors that are present in combination with process colors or other spot colors may consist of several process colors after conversion. This option is suitable for digital printing, large format inkjet printing, proofing or offset printing with a fine screen ruling.

Use the least Amount of Channels possible option converts solid tones and gradients of the spot color with a minimum of channels and colorimetrically accurately, however after conversion, overprinting spot colors are composed of as few process colors as possible from the target color space. Choose this method for packaging printing, where the purest possible colors are to be produced. Single-color and two-color combinations are also included in the search for the best color combination.

Use a Maximum of two Channels: Best for one or two process colors providing the best colorimetric match automatically selected for each spot color. The result is, very clean separations that are easily printed, but not necessarily very exact in colorimetric terms.

Details: It is recommended to only use this function for individual, manually created spot colors.

ZePrA converts spot colors automatically visual and print (channel minimizing) optimized. A visually optimized conversion will prioritize the lowest visual color difference based on DeltaE 2000. This may lead to the fact that more process colors are used to simulate the spot color. With a channel minimizing method we prioritize the usage of less possible channels while maintaining a low DeltaE 2000 value. Obviously, channels will only not be used if the resulting color is still close enough to the original spot color. Spot color shades will only be printed with those process colors, which are defined for the full tone either manually or with the help of the Auto function. In addition, color combinations of spot colors with process colors or other spot colors in the files are analyzed and converted to the target color space by one of the four calculation methods.

Gamut Warning

The Spot Color module delivers extremely accurate color rendering in the conversion of spot colors to process colors. However, it is possible that some spot colors are outside the printable gamut of the target profile and thus preclude precision rendering. Configure ZePrA with a deltaE Limit (dE 2000) to issue a Gamut Warning.

Choose a Gamut Warning

Choose a Gamut Warning

None: No warning or error message during spot color conversion to the target color space.

Display Warning and Continue: A warning is generated during conversion of spot colors (the processed file highlighted in yellow in the Jobs and Queues Overview) when the dE2000 Limit specified is exceeded during conversion of spot colors to their target color space. The file is then converted and placed in the Output folder.

Display Error: The file is not converted, then highlighted in red under Processed Jobs in the Jobs and Queues Overview and moved to the Error folder.

Keep Spot Color and Show Warning: The spot color with a warning will not be converted but preserved but all the other spot colors will be converted. The converted file will be placed in the Output folder or the Warning folder (if specified under the Queue) and yellow warning is shown under Processed Jobs in the Jobs and Queues Overview.

Clip Output Values Below (0-20)

Defines a user defined percentage value. The feature specific for Flexo print production.

Example: If printing tints below 3% is unstable on press then 3 needs to be entered as threshold in the number field. ZePrA would then not use any process color breakdowns with less than 3%.

Note: If this feature is used and the threshold is set too high, it will be likely that a converted light spot color will result in higher deltaE values. Use caution when setting the percentage.

Printing sequence

Another aspect that plays a role in connection with the opacity (see also Special Settings/Spot Colors/Create spot color libraries), is the Printing Sequence for transparent spot colors. There is a difference in the color reproduction depending on whether the spot color Silver is on top of or underneath the spot color Orange as shown in the two examples below (left: Silver over Orange, right: Orange over Silver).

gwgexamplepdf-x4_printsequence_orange-silver-white gwgexamplepdf-x4_printsequence_silver-orange-white

If transparent spot colors are to be converted into process colors, ZePrA takes into account the opacity and the printing sequence of spot colors in the sequence that the spot colors in the configuration were manually created.

px_printing-sequence

To change the sequence, go to the Configuration tab under Convert Spot Colors, click and hold any spot color that have been created in the table and drag it to the desired point in the sequence.

Note: The PDF specification allows the printing color sequence to be saved. If the printing sequence is correctly defined in the PDF files and the checkbox Use Printing Sequence from Document, if possible is enabled, ZePrA can apply it without having to create all of the spot colors in the right order in the table. Please note that this feature is rarely set or used by PDF-creation programs.

For ZePrA to correctly interpret the printing sequence, several spot colors in PDF files have to be created together in one DeviceN object.

Dont Convert "All"

Register marks and other black printer marks are often created with the specific spot color “All”. In order to avoid conversion of this specific spot color to the target color space, as soon as the Convert Spot Colors to Target Color Space option is activated, the checkbox for Don’t Convert Spot Color “All” is enabled by default.

CIE Conversion

The CIE Conversion Settings option is very useful for special applications such as textile printing. In the textile industry the standard illumination is D65 and the 10 degrees standard observer is the default. Users can change the Lab values that are used in ZePrA for conversion by selecting the desired  Illumination and Observer options. Changes in the dialog only applies for spectrally defined spot colors and only makes sense if the target profile was created with a matching illumination and observer.

zepra5_config-spotcolor-illumination

Note: The default setting is D50 and 2 degrees observer.

The Illumination drop-down menu contains several options. Printer profiles are typically created for the D50 viewing condition. However, if it is required to set up photos in a gallery illuminated by the light of incandescent lamps (corresponding roughly to light source A), or displays at an exhibition where the lighting conditions might be challenging (e.g. fluorescent light), the lighting conditions can be taken into account. Select either one of the three predefined viewing conditions, or enter the measured viewing condition manually in the form of a Kelvin or an XYZ value. ColorLogic has added the Emission option as a powerful new tool to customize illuminations. The Emission option allows the user to select spectral emissions readings of a specific light source by either loading a CxF3 or text file. To quickly load a file drag-n-drop a measurement file with the measured light onto the value field.

Editing Spot Color Conversions

ZePrA has the option to control individual spot colors on a Configuration level. This feature is specific to modifying the printing sequence of a file, or performing specific modifications to a spot color.

Selecting a Spot Color

Select the spot color by entering the Name of the spot color. For conversion of individual spot colors in the PDF files or to modify specific spot colors, access the processing options for each individual spot color.

When a spot color is displayed:

If the spot color is available in the color libraries under the name entered, the names of the libraries are displayed next to the option Library, and the Lab color value together with a true-color preview of the spot color are displayed in the Information section underneath.

Choosing a spot color

Choosing a spot color

If several libraries are shown, the same spot color name exists more than once, and choose the correct Library for this configuration.

If the spot color is not displayed:

If the spot color is not available in the color libraries, the Library option remains disabled.

Tip: Check the spelling of spot color names. Upper- and lower-case characters and the use of wildcards, work as they do for Gradations (see the chapter Configuration – Apply Gradations/Applying gradation curves to spot color channels). Underscores in name elements are interpreted as spaces.

If the spot color name was not found, specify an Alias. To do so, select the Select button next to the Library option.

The Select Spot Color dialog opens. Select the desired Library in this dialog and all the spot colors in that library will be displayed.

Select the name of the spot color you want, then click OK.

Tip: To simplify the search, type in part of the name in the field below the table. All spot colors with names that include this character string are then displayed instantly. Click on the X icon to delete your search entry.

in the Processing Options for Spot Colors dialog, the alias name of the spot color is now displayed and used for further processing.

Note: If the color selected as the alias has already been created in the table, the color conversion that was set up in the table is used. This ensures that identical colors are always processed in the same way.

  1. The Conversion field directly below the name of the spot color offers a choice of three options for defining how ZePrA is to process the spot color:

No Conversion leaves the spot color untouched.

Alternate Color Space from PDF ignores the library and instead uses the alternate color value (alternate color space) defined for the full tone of the spot color in the PDF file. This option is available for compatibility issues with standard conversions in other tools. However, the high-end ColorLogic technology is used for calculating overprinting colors.

Output Values:  Makes it possible to display the output values automatically calculated by ZePrA. The calculated output values are grayed out in the Optimize Output Values field below.

Apply to: Specify whether the color conversion should apply to Images only or Vectors only, or both. The default selection is Images and Vectors. This allows creation of the same spot color twice and performs different conversions for Images and Vectors.

Calculation Method: Six options are available. The calculation method has an impact both on automatic output value optimization and, in particular, on overprinting spot colors.

Note:  When changing the Calculation Method and the Automatic checkbox under Optimize Output Values is enabled, the color values will be updated automatically.

Spot Color Matching Options:

Use Same Method as Configuration: Default setting. Manually selected spot colors can also be calculated differently from the global method used in the Spot Colors configuration.

Precise Match – Proofing: Reproduce spot colors on a proofing printer as precisely as possible. This method is not meant to be used in production as it may use all process colors to achieve the closest match (based on DeltaE 2000). The full tone is calculated that results in the lowest possible DeltaE 2000 value. No channel minimizing and print optimization is applied.

Visual Match – Utilize more Channels: The visually best conversion with high colorimetric accuracy and with good printability. Solid tones and gradients of spot colors are converted with a minimum of channels and are still colorimetrically accurate. Spot colors that are present in combination with process colors or other spot colors may consist of several process colors after conversion. This option is suitable for digital printing, large format inkjet printing, proofing or offset printing with a fine screen ruling.

Use the Least Amount of Channels possible: Possible option converts solid tones and gradients of the spot color with a minimum of channels and colorimetrically accurately, however after conversion, overprinting spot colors are composed of as few process colors as possible from the target color space. Choose this method for packaging printing, where the purest possible colors are to be produced. Single-color and two-color combinations are also included in the search for the best color combination.

Use a Maximum of two Channels: Useful for print packaging production, the spot colors used for text and bar codes should be converted using a maximum of two process colors

Use one Output Channel only: Useful for print packaging production, the spot colors used for text and bar codes should be converted using a maximum of two one process color.

Spot color options and editing

Spot color options and editing

Optimize Output Values

This provides numerous possibilities for controlling how the solid tone of your spot color is to be converted to the target color space. The color channels displayed correspond exactly to the channel names used in the target color space and later in the converted PDF file.

The Automatic checkbox below Optimize Output Values is activated as the default setting, ensuring the best possible optimization of the conversion in terms of printing and color in accordance with the selected Calculation Method. The calculated process colors are grayed out in the value fields and can’t be edited. In the Information section see the Actual Lab and DeltaE /2000 calculated for the spot color.  

As soon as the Automatic checkbox is deactivated, enter process color values in the fields for the process colors. The color impression to be expected with these color values is displayed as the Actual Lab and in the color preview. Specify different values in order to check what color results could be obtained.  

It is also possible to specifically map a spot color onto a process color channel by entering a value in the required channel and setting the other channels to zero.

Use the DeltaE-76 or DeltaE-2000 buttons to perform the best possible color calculation based on specified values for the channels of the target profile.

The Lab color value is calculated and displayed under Information, as is the expected color difference compared to the original color in Delta E (76)/2000. Using the two buttons, the calculation is performed strictly according to the colorimetric rules and does not take into account any technical printing aspects, as would be the case with the Automatic function where channel minimization takes place.

Tip: When minimizing Delta E, use the checkboxes for the process colors to manipulate the calculation. Only the active channels are changed during calculation.

Example: Use of the individual channels not wanted, enter a value of zero for these channels and deactivate them. It is also possible to make sure that a channel with 100% coverage (or any other value) is not changed by entering 100% in the value field and deactivating the checkbox. When calculating the minimum Delta E with one of the two buttons, the 100% value of this channel is then taken into account for calculation, but not changed.

In the Information area, view the measured value from the library under Original Lab and the color value calculated with the selected process colors of the target profile under Actual Lab.

In addition, the color difference to be expected is displayed, both in DeltaE (76) and DeltaE 2000

With Paper White Simulation enabled, the coloration of the substrate, which represents the target color space, is taken into account. Calculation of the Original Lab, Actual Lab value and color distances (DeltaE) is performed accordingly.

Note: It is recommended to enable Paper White Simulation.

Split Color Preview: The split color preview shows how the original color (top, left‑hand triangle) and the calculated color (bottom, right-hand triangle) will look when printed. The color preview is in true color on a calibrated and profiled monitor. (image)

Spot Color List

The list of spot colors to check specific spot colors or to define their conversion independently of the automatic processing in ZePrA, or if to define the printing sequence for spot colors. There are various ways to add relevant spot colors to the list in the Spot Colors tab.

Accessing a Spot Color from the list

Accessing a Spot Color from the list

Name: Displays the name of the individual spot colors

Conversion: Displays the method of conversion – Output Values, Alternative Color Space or No conversion. Setting can be changed in the Edit Spot Color Conversion dialog.

Value: The table for loaded spot colors shows whether the target values are automatically calculated or have been manually set. Where target values have been manually defined, they are shown as numeric values in the Value column.

Apply to Column: Shows what the conversions have been applied to- Images only, Vectors only, or to both Images and Vectors according to the presets in the processing options.

Printing Sequence: Displays the assumed printing sequence of spot colors. 

New, Edit, Delete, Import, Export: Access the spot colors from the libraries already saved. New spot colors can also be defined or add previously exported spot colors (.ccf file).

Access and edit the processing options for spot colors by:

  1. Clicking on New
  2. Double-click on a spot color in the table and enable Edit  

Quick Access: Right-Click on one of the spot colors to bring up a context menu which can be used to change the processing mode individually for selected spot colors.

Working without the Spot Color Module

Without Spot Color license, it is not possible to create nor use color libraries. Accordingly, the Global Setting for creating Spot Colors is not available on the navigation panel.

In the Spot Colors tab under Define Configuration in ZePrA, use the Convert Spot Colors checkbox to resolve and convert all spot colors created as DeviceN colors. However, only the alternate color value stored in the PDF is used for the conversion. This alternate color value may be indicated as CMYK, RGB or Lab color definitions.

Depending on the color space of the Alternate Color Space, colors are processed with the CMYK, RGB or Lab settings made under Images and Vectors in ZePrA. Be sure that the settings selected match the conversion goals. Conversion via the alternate color space is very limited compared to using spot color libraries and, for quality reasons, is not recommended.

The Don’t Convert Spot Color “All” option is automatically activated to prevent unwanted conversion of register marks and other printer’s marks.

Without a spot color license, the options for selecting Spot Color Libraries and Calculation Methods are grayed out and cannot be used, as are the other options. In the table below, use the New button to enter the name of a spot color that you want to exclude from conversion.  

In the Edit Spot Color Conversion window, enter the exact name of the spot color as indicated in the PDF. The use of upper and lower case letters is not important in this context and is automatically recognized by ZePrA.

Select the No conversion option in the Processing area.

Other spot colors to be resolved with the PDF substitute color (alternate color space) do not need to be explicitly specified because the PDF alternate color space is always used automatically. The other attractive processing options are not available without a spot color license.

Note: Purchase the additional module for processing spot colors at any time.