Document Color Space
The document color space acts as a reference to define a uniform color space for the colors of the PDF file.
- CMYK color spaces are usually used for print production, as CMYK colors are generally used for printing.
- RGB document color spaces are suitable for web, mobile or multimedia applications.
- Multicolor color spaces are often used in HiFi packaging printing or in modern digital printing.
ZePrA supports the full spectrum of color spaces (Multicolor color spaces require a corresponding Multicolor license). If there are individual RGB or CMYK objects with embedded profiles in PDF files, these are converted to the document color space by default (except in Auto Setup mode Direct Color Conversion to the new Output Condition). If necessary, this can be changed in the Images/Vectors tab. For professional print productions, the data exchange is based on the PDF/X standard.
The document color space can be defined either by the output intent of the PDF/X file or by the ICC device profile that was (most likely) used when the document was created. If the file does not contain an output intent, select an ICC device profile under Document Color Space. The color space of the selected profile is displayed next to the drop-down menu.
Prefer Output Intent
In PDF/X documents, the document color space is defined by the output intent. By activating this checkbox, the output intent of the PDF/X file is used vs. manually setting the document color space.
For non-PDF/X documents, select (in addition to the ICC device profiles of the individual PDF file objects) an ICC device profile as the document color space that defines the color space of the entire PDF document.
If Prefer Output Intent is enabled, PDF/X files with several output intents can be correctly converted in a queue because the respective output intent is considered instead of the document color space. In this case, it is recommended to work with SmartLink instead of a fixed DeviceLink profile when converting from document to target color space.
- This function is only suitable for PDF/X files.
- If you have reason to believe that the output intent of a PDF/X file has been set incorrectly, specify a suitable ICC profile as the Document Color Space and uncheck the Prefer Output Intent checkbox.
PDF 2.0 Support
PDF 2.0 files can have page level output intents. In regards to color conversion, the means different pages can contain different output intents. The checkbox Prefer Output Intent in the Document/Target tab must be enabled to consider this type of output conditions for the conversion. If the checkbox is enabled all objects on each page will be converted to the Target Color Space with the settings defined under the Image/Vector and Document/Target tabs using the corresponding output intent of each page.
Disabling the checkbox ignores the page level output intents and the conversion is done for all pages using the same source ICC profile defined as Document Color Space.
Another major feature of PDF 2.0 files is the support of black point compensation in combination with the relative colorimetric rendering intent.
Target Color Space
Under Target Color Space, select the target ICC profile. If the document color space/output intent of a PDF/X file does not match the color space of the final printing process, the entire PDF file needs to be converted from the Document Color Space to the Target Color Space. For the best quality of the conversion DeviceLink profiles or SmartLink can be used.
In addition to the selected target profile, the color space of the target profile is also shown, which is especially useful for Multicolor profiles with 5, 6 or 7 channels.
Moving the mouse over the color space icon displays the channel names of the Multicolor target profile.
Setting the Target Color Space
The Target Color Space is defined by the target profile selected in the drop-down menu. If the configuration was created with Auto Setup, the selection is automatically made by selecting the target profile or a DeviceLink. If required, the target profile can be changed here.
Embed into Output File: Embeds the target profile into the file after conversion.
Maintain Output Intent: The output intent of the file is used as the target profile instead of the selected target profile. The colors are converted to the output intent instead of the selected target profile.
This function should only be used if no changes to the output intent are necessary, or when simply normalizing a PDF/X file.
Usually, it is not intended to leave the output intent unchanged during color conversion. However, if this is required, set the Output Intent PDF/X in the PDF tab to Don’t change.
Notes: If the file has no output intent, this option has no effect.
Embedded profiles in image files (TIFF, PSD, JPEG) are not regarded as output intent. Therefore, this function has no effect on image files.
Apply Correction DeviceLink Profile
Variations in printing due to new paper batches, different tone value increases, or changes in inks can be compensated for with updated profiles and Correction DeviceLinks.
Apply Correction DeviceLink Profile: This checkbox becomes available when a Correction DeviceLink profile for the target color space exists.
- Create a Correction DeviceLink profile with CoPrA.
- In ZePrA, activate the Apply Correction DeviceLink Profile checkbox under Configurations in the Document/Target tab.
- Click Settings and select the Correction DeviceLink profile.
- Embed the updated Target Profile instead of the Target Profile: Embeds the corresponding optimized target profile into the converted file. This profile then becomes the new output intent of the converted PDF file. The corrected target profile is displayed.
Note: ZePrA checks whether suitable Correction DeviceLink profiles and optimized printer profiles exist for the selected Target Color Space. Only corrected or optimized profiles are shown and can be selected after activating the Apply Correction DeviceLink Profile checkbox. If there are no Correction DeviceLink profiles, the checkbox is grayed out.
There are four conversion methods:
- DeviceLink Profile
Conversion of the complete PDF document via a DeviceLink profile
A DeviceLink profile represents a tailor-made color conversion from a defined source to a target profile. Within the ICC standard, a PSID tag can be used in the DeviceLink profile to store information regarding the source and target color spaces of the DeviceLink profile. If a DeviceLink profile has been selected, ZePrA can read its PSID tag and automatically define the profiles under Document Color Space and Target Color Space.
Note: All ColorLogic DeviceLink Sets from profile version CoLoV3 and higher contain PSID tags.
- Select SmartLink as Conversion Method (only available if licensed)
- Select the SmartLink Method to be used for on-the-fly calculation of DeviceLink profiles from the Document Color Space to the Target Color Space.
- Select the appropriate Rendering intent
- Device Profile
Conversion of the PDF document with an ICC device profile
Converts the PDF document from the Document Color Space to the Target Color Space using the ICC device profile set under Target Color Space. Select the corresponding Rendering intent.
- No Conversion
The document is not converted to the Target Color Space. Other color conversions defined under Images/Vectors or Gradations or Spot Colors still take place.
Example: A basic print-ready PDF (which does not need to be converted) still contains spot colors that must be converted to process colors.
General information on the design of ICC device profiles:
Rendering intents, such as Perceptual or Relative Colorimetric with CMYK profiles, contain large tables which convert either CMYK color values to Lab or Lab color values to CMYK.
Due to the two color conversion directions, there are two tables for each rendering intent. The tables are calculated from the measurement data when a color profile is generated.
If ICC device profiles are calculated from the same measurement data – but with different profiling programs – then the tables generated can differ considerably in some color ranges.
This is especially true for the two tables of the Perceptual intent, for the gray balance and also for areas with very high color saturation in the two tables of the Relative Colorimetric intent (also called “Out of Gamut” colors).
For optimal and harmonious color conversion, it is recommended (especially with CMYK-to-CMYK color conversions) to ensure the source and target profiles were calculated with the same profiling software.
Profiles from different providers (such as Adobe, ECI, or ColorLogic) are often used in practice, which can lead to problems in color conversions based on the perceptive rendering intent.
These problems can be avoided by using SmartLink.
The SmartLink module uses the source profiles embedded in PDF or image data and automatically calculates the DeviceLink profile required for conversion between source and target for each object and applies it at the object level. The main conversion from the document color space to the target color space is also carried out via SmartLink. SmartLink is ideal for processing external data from a wide variety of sources to ensure optimum color accuracy (via DeviceLinks).
Additional SmartLink Rendering Intents
The SmartLink module provides five additional rendering intents to avoid problematic color conversions, which can result from tables calculated differently for source and target profiles.
To ensure precise color conversions, ZePrA completely recalculates the conversion of source and target profiles on-the-fly. The algorithms are the same as in ColorLogic’s CoPrA profiling software.
Note: These additional rendering intents are only available with SmartLink enabled. If the checkbox Use SmartLink is not activated or SmartLink has not been licensed, only the four standard rendering intents will be available.
Standard Compression: For conversions involving different gamut sizes. Calculates a perceptual conversion for input and target profiles that is suitable for all types of gamuts. The appearance of the gray axis always depends on the paper white of the target profile. With CMYK data on a very yellowish paper, the gray axis of the converted file also looks yellowish. The same grey axis will look bluish on a bluish paper. The Standard Compression considers different gamut sizes. For very small color gamuts (newspaper printing), the dark tones are slightly raised to achieve more definition in these areas.
Black Point Compensation: Use Black Point Compensation to achieve the same results with a perceptive conversion as with “Relative Colorimetric with Black Point Compensation”. When converting from large to small color spaces, the image definition is preserved in the highlights and shadows, unlike with a pure Relative Colorimetric conversion. Neutral tones are converted using the colorimetric intent. Out-of-gamut colors are cut off.
Absolute Compression: For conversions where the color gamuts are similar but the paper tones are very different. In contrast to the Standard Compression and Black Point Compensation, the gray balance compensates for the paper color. This ensures that the color impression of the original file is preserved in the best possible way on a target medium with a different paper color. This method also raises shadow (darker) areas when using small color gamuts.
The gray axis of a source color space will look largely identical to the original after conversion (for example, on a yellowish or bluish paper).
Dynamic Compression: Compares the source color space with the target color space and generates a compression that minimizes out-of-gamut areas. This setting preserves the brightness of the original color space while reducing the saturation, and therefore also preserves the image definition. As for the Standard Compression, the gray axis of the conversion is built relative to the paper white of the target profile.
Minimum Compression: This method is mostly similar to the absolute colorimetric intent and only compensates close to the black and the white point. Maximum shadow contrast will be achieved, image definition will be preserved, and the paper white will not be simulated. Use this rendering intent if you would like to obtain a very close reproduction, for example, when using print standards like ISO Coated V2 or GRACoL2006 Coated1v2 on a digital printer.
Note: Remember that the target color space should be larger than the simulated color space (or similarly large) to avoid loss of detail and vividness (similar to the absolute colorimetric rendering intent). For conversions from large to small color spaces, instead use our rendering intent Absolute Compression if the gray balance of the source color space is to be preserved.
Important: To ensure that an on-the-fly DeviceLink profile created with SmartLink uses the rendering intent set under Configurations > Images/Vectors, select the checkbox Ignore PDF Rendering Intents in the Options tab.
The SmartLink function uses the ICC device profiles set in ZePrA, or embedded in images and PDF files, to create DeviceLink profiles on-the-fly. Supported color space combinations include:
Define SmartLink Conversions
The SmartLink Method considers the specific requirements of different printing conditions so the printed color is correctly reproduced and optimally separated for the printing process.
Traditional Printing – Classic: Conversions for offset, gravure, or newspaper printing. The DeviceLinks created ensure that black and gray, as well as the primary, secondary and triplex hues of the source profile, are preserved. The total area coverage is taken from the target profile.
Traditional Printing – Automatic: Select this setting when the colors and paper of the target color space are significantly different from the output intent or document color space. Separation is preserved, but Exceptions for special colors such as black and gray, primary, secondary, and triplex colors are automatically calculated based on both profiles.
Large Format Printing – Inkjet: The separation is characterized by a strong GCR and a late black start. The black point and total area coverage are automatically calculated to ensure the best color reproduction. The Exceptions for special colors, such as black and gray, primary, secondary, and triplex hues, are automatically calculated based on both profiles. To avoid problems that can occur when colors vary between different inkjet printers or between the inkjet printer and the source color space (as with ISOcoated V2 or GRACol), the Large Format Printing – Inkjet method automatically calculates the required exceptions in these cases.
Digital Printing – Toner: For toner-based digital printers and office printers. This method uses the same DeviceLink presets for Exceptions as Large Format Printing – Inkjet. The separation method ensures that a high percentage of black is used. This will achieve a stable print and neutral gray balance. The total area coverage is taken from the target profile. The Exceptions for special colors, such as black and gray, primary, secondary, and triplex hues, are automatically calculated based on both profiles.
Note: All methods that automatically calculate Exceptions can result in grey, primaries, and secondaries being built with multiple colors, which can lead to overprinting problems in complex PDF files. If SmartLink has not been licensed, the Auto Setup Wizard creates configurations differently to avoid overprinting problems. Without a SmartLink license, CMYK objects with embedded profiles are treated like objects without profiles and are converted with the selected DeviceLink profile.
If one of the four mentioned standard SmartLink methods has been selected, no further SmartLink settings are necessary.
TAC Reduction: Reduces the total amount of ink applied while maintaining color perception. This method is only available if the CMYK profiles for the Document Color Space and the Target Color Space are identical.
The required maximum ink application can then be specified in percent under Settings. By default, the TAC settings are read from the profile of the Target Color Space.
SaveInk: Reduces overall ink application while maintaining color perception. This method is only available if the CMYK profiles for the Document Color Space and the Target Color Space are identical. Predefined methods can be selected under Settings. With Import, you can also import your customized settings created (and exported) with CoPrA. SaveInk requires ZePrA XL or higher, or a SaveInk and SmartLink license.
SaveNeutral: Moderately increases the amount of black in neutral color areas. Ideal for print shops looking for a quick introduction to saving ink and wanting to gain practical experience. These profiles primarily stabilize the printing process and are less suitable for saving large quantities of ink.
SaveStrong: The black portion is significantly increased. This is aimed at print shops that have control of their printing process in accordance with standardization and are looking for high ink savings, but still want to leave room for adjustments on the press.
SaveMaximum: Maximizes the amount of black and provides the greatest ink savings. Mainly suitable for print shops that have successfully implemented standards and control them completely.
Custom: Enables the Settings button, allowing to customize all color space settings.
Under Settings > SmartLink Settings, specify how to convert to the Target Color Space. This includes the conversion from the Document Color Space as well as from Images/Vectors to the Target Color Space.
Pre-defined methods or custom methods created by CoPrA can be selected for all color space conversions. Import can also be used to import custom settings created (and exported) by CoPrA.
Using CoPrA’s DeviceLink Settings in ZePrA
Because of the close connection between CoPrA (ColorLogic’s profiling solution) and our color server ZePrA, the profile settings from CoPrA can be used to calculate DeviceLink profiles in ZePrA.
By selecting the checkbox Share with ZePrA in CoPrA, the settings of your DeviceLink and SaveInk profiles are transferred directly to ZePrA and can be used there as SmartLink Method.
The DeviceLink tool in CoPrA: SmartLink can use the profile settings from CoPrA to create DeviceLinks in ZePrA.
To do so, make all the required settings in CoPrA by entering all relevant information in the DeviceLink tool under Rendering, Exceptions, and Color Generation. Detailed information on all functions and DeviceLink settings can be found in the CoPrA help under DeviceLink. Click Save As and then activate the Share with ZePrA checkbox. Enter a name for the setting and confirm with OK.
The so created methods shared with ZePrA are then available as SmartLink Method in the drop-down menus of both the Auto Setup and the Configurations.