ZePrA | Proofing

Proofing

Color-consistent simulation of the printing result

Proofing

ZePrA’s sophisticated technology – e.g. the quality of DeviceLink and SmartLink profiles and the spot color rendering of its advanced spot color module – can be used for proofing as well. This is especially useful as many RIPs do not support CxF/X-4 data and SCTV calibration nor have a spectral color prediction model for spot color rendering.

The Proofing tab under Configuration contains all Media wedge settings and the Proofing Information label.

Media Wedges

Two types of media wedges can be used:

  1. Media Wedge in Simulation Color Space: Can be used to determine the accuracy of the proof. This media wedge is converted based on the color management setting defined in the various configuration tabs.
  2. Media Wedge in Proofer Color Space: Allows using a second media wedge that is not color managed. It must be in the color space of the proofer and can be used to determine the stability of the proof printer.

Choose a Media Wedge.The media wedge is added outside the document’s media box to verify the proof. This can either be a dynamic or an external media wedge.

Dynamic Media Wedge: Uses the color space information of the simulation color space and dynamically adds all spot colors of the documents to be processed. The required reference files for measuring the wedges are created on-the-fly by ZePrA. They will be saved in the Folder for Report and other Data folder of the proofing queue that has automatically been set up by the Auto Setup Wizard.

The reference files for dynamic media wedges contain both the device values (DCS values) and the target Lab values. The target Lab values are also calculated for the spot colors of the job and incorporated into the reference file in addition to the color values of the document color space. This is done according to the settings under Configurations > Options (solid tone only or gradation values as well) and Configurations > Spot Colors.

The measured values obtained can then be immediately compared to the target Lab values (e.g. in ColorAnt/Compare). Use these reference files in appropriate tools, such as ColorAnt’s Measure Tool, for measuring.

Note: Reference files are not created when the report folder Folder for Report and other Data is missing. If you convert a normal queue by enabling proofing, you must create this folder manually so that a reference file can be created. If this folder is missing, no reference file can be created.

Reference files are created for each job in the queue and named as follows:

Jobname_DynamicMediaWedgeReferenceSource
Jobname_DynamicMediaWedgeReferenceTarget

If dynamic media wedges are selected for source and target color spaces, two reference files for each job will be created.

Note: If the same job is run again, the reference file will be overwritten. This means that if the spot color patches are changed under Options, a modified reference file is saved, and any previous conversion with the reference file with a different number of patches is lost.
The use of spot colors for the dynamic media wedge can be defined under Options 

Media Wedge from File: Can be media wedges such as the FOGRA, UGRA, Idealliance* or other media wedges. For external media wedges, the corresponding reference file is required to measure the printed wedge. Measurements can be done with any proof evaluation software or with ColorAnt’s Measure Tool.

*The IDEAlliance ISO 12647-7 Control Wedge 2013 is included in ZePrA and available under /Users/Shared/ColorLogic/MediaWedges (Idealliance ISO 12647-7: 2013, 3-Row Digital Control Wedge ® is a registered trademark of the Idealliance).

Note: A separate ColorAnt license is required to use the measurement and comparison features.

Proofing Information: Enabling this checkbox will add text information which are in accordance with ISO 12647-7 such as information about the job, date and time, conversion settings and the software used. The information that will be added to the converted file can be verified and edited in the text field. For editing switch to Custom.

Position: The two media wedges and the proofing information label can be positioned independently on the converted document. For each of these 3 elements, the user can specify where it should be placed. Positioning options are: Automatic, Bottom Margin, Right Margin, Top Margin, Left Margin. The elements are placed outside the media box of the document according to this setting. This results in an enlarged media box in the converted document. Automatic is suggested as default settings for all 3 elements to make sure that they are placed together on the converted job.

Options: General settings and settings for Dynamic Media Wedges can be defined unter Options.

Media Wedge Options

General

Font Size: Defines the font size used for the proofing information label in points.

White Space: Allows the placement of margins on media wedges by entering a user-defined distance in mm. By default a white space of 15 mm is added. This ensures that enough white space is added on the left and right of the placed media wedges which some instruments need for correct measuring. The White Space margin applies both to external and dynamic media wedges.
Note: If the external media wedge already has a margin, we recommend entering 0 mm as White Space. As a rule of thumb the white space in millimeters for dynamic media wedges should be at least the size of the Patch Width. The white space of the Media Wedge in Simulation Color Space is color managed whereas the white space of the Media Wedge in Proofer Color Space is not.

Place on every page: For multi-page PDF files media wedges can be placed on each page. By disabling the checkbox media wedges will be placed on the first page of the PDF only.

Dynamic Media Wedges

Defines the Default Chart Width, the Patch Width and the Patch Height of the dynamic wedge.

Gap Size: To separate individual patches. Select the width in mm.

Patch Distribution: Defines the distribution of patches on the media wedge.

  • Randomize: Color patches are distributed randomly.
  • Normal: Color patches are distributed as specified in the reference file.
  • Sorted: Color patches are sorted from light to dark.

Patches per Spot Color: Defines whether spot colors are to be used in the dynamic media wedge and, if so, whether tints are to be used.

  • None: No spot color is added to the dynamic wedge.
  • Solid Tone: Only the solid tone of each spot color in the job is used in the dynamic wedge.
  • 3 Patches: Uses the following patches for each spot color: 100%, 70%, 40%.
  • 5 Patches: Uses the following patches for each spot color: 100%, 70%, 40%, 20%, 10%.

Exclude Colors from dynamic wedges: Spot colors are used in documents for various reasons besides printing purposes, e.g. to illustrate the DIE cut lines, or varnish, braille or other non printing elements. Obviously, those colors are not to be used in the dynamic media wedge. To avoid using them in media wedges, create a library (or more if needed) containing all spot colors to be excluded and select it (or them) from the list under Exclude Colors from dynamic wedges. This list contains all spot color libraries managed by ZePrA. Enable the checkboxes of only those libraries which contain the colors to be excluded.

The selected libraries containing the colors to be excluded are also applied to spot colors of external media wedges. Typically, if the Document Color Space is Multicolor, ZePrA assignes the channels of the Document Color Space to the channels of the media wedge. This is intended in most cases, e.g. if a 7C media wedge with generic channel names is used for a 7C Document Color Space in such a way that the channels are associated. However, this is not intended in case a spot color White is to be used as 5th channel and the 5th channel in the Multicolor profile of the Document Color Space is called Orange (for example). To retain the white spot colors an exclusion library which contains White as non-printing color can be selected.

ZePrA | Job Warnings

Job Warnings

Customize job warnings for configurations

Customize Job Warnings for Configurations

In general, job warnings and error messages will be issued when problems or errors occur while processing a file. Files with a yellow warning in the Overview window have been processed but may have issues. They are placed in the Output Folder. Alternatively, when configuring the Queue, define an Output Folder with Warnings, where such files will be moved after processing. Incorrectly processed files, fatal errors or unsupported file types are highlighted in red and are moved to the Error Folder.

The list contains all existing warning messages. Their behavior can be customized independently for any configuration, for example if you don’t want a warning message for a certain problem or if you feel that a problem is so serious that it should better be treated like an error.

Note: The behavior of error messages can’t be changed.

Job Warnings can be adjusted individually: Right click on the desired job warning to open the context menu. Select Inactive, Active or Active (Treat as Error).

Inactive: Deactivates the job warning in the selected configuration. The Overview window no longer displays a yellow warning.

Active: Activates the job warning in the selected configuration.

Active (Treat as Error): Treats the associated problem like an error. The file will be highlighted in red and moved to the Error Folder.

Reset: Resets the changed warnings to the default settings.

ZePrA | Spot Color Iteration

Spot Color Iteration

Iterate spot colors to improve or maintain quality

Iterate Spot Colors

Spot Color Iteration is a process that involves printing of the spot colors converted from ZePrA on the printer to be used for the print job, followed by measuring test charts and optimizing the color differences (expressed in deltaE2000) until the measured deltaE values are within the desired tolerances. Printing the test chart and applying the Iterate Spot Colors feature once only already results in an improved spot color rendering which is usually close to the optimum of this printer.

Why can spot color iteration be required?

First of all, be assured that ZePrA already calculates the best possible spot color conversion based on the target profile set under Configuration/Target Color Space. However, printers, inks and papers drift over time so that there are always some deviations from the state the printer was profiled. During spot color iteration we measure how converted spot colors are actually printed in the current state, and subsequently optimize the deltaE2000 values. The iteration report shows which colors are improved and where restrictions based on the color gamut or the spot color Calculation Method occur so they can’t be optimized further or if additional iteration steps are recommendable.

Procedure

Open the Iterate Spot Colors dialog right from the Spot Colors tab of the Configuration you would like to optimize or the Tools menu and follow the steps from top to bottom. A Spot Color module license is required to use the tool.

Step 1: First, select the Configuration you would like to use for printing. The option Convert Spot Colors must be enabled in this configuration.

Notes: The best approach for the iteration of spot colors is to set the Calculation Method to Precise Match or Visual Match in the appropriate Configuration.

The setting Use the least Amount of Channels may be insufficient for iterating spot colors. Importantly, spot color iteration will not work when the spot color conversion is set to Convert using Alternate Color Space from PDF.

Step 2: Select the source of the spot colors you would like to optimize. You can either choose a PDF or an image file with spot colors or a complete spot color library. In the following example we will use a PDF file with spot colors as source file.

Step 3: A test chart file will be created from either a PDF or Image File or a spot color Library. If you select a PDF file and click on the Save button, ZePrA will extract all spot colors (full tones) used in the file and convert them using the selected configuration. In this step select an Instrument Setting for your measuring instrument. In the Save dialog, choose either a PDF or TIFF file type to create a test chart which contains the spot colors as a strip optimized for your measuring instrument. In addition, the  associated reference file for measuring will be created. The newly created test chart needs to be printed on the printer to be used for the print job.

Note: The test chart contains the converted spot colors as given in the Configuration using the conversion settings and Calculation Method defined in the tab Spot Colors.

Step 4: Print the test chart on your printer. Do not apply any color management when printing the test chart.

Step 5: Subsequently, measure the printed test chart using ColorAnt/Measure Tool or an appropriate software. The required reference file which is needed for measuring the spot colors will be shown in step 3. Click on Measure to open the Measure Tool in ColorAnt. The reference file will be selected automatically so that you can use the tool right away for measurements with your instrument. For information on how to use the Measure Tool in combination with your instrument follow the instruction given in the online help. Alternatively you may use the provided reference file for measurements with other tools.

Step 6: This step is optional but highly recommended. If you click on Save Report a Spot Color Iteration Report will be generated. The report provides you with information about the achieved and measured deltaE values.

The last column of the report – Status – provides status information such as improvements, recommendations about further processing or warnings. If the deltaE00 value is already very low (lower than 1) further optimization is not needed and the color is marked green. Colors that are marked yellow are higher than 1 but below 2 dE00 and colors marked orange are higher than 2 dE00. For colors that have been improved by an iteration the improved value is shown in brackets expressed as deltaE behind the status. If a spot color is out of gamut or optimization is not possible due to restraints from the selected configuration those colors are marked accordingly. A Legend below the table of the report explains the different statuses.  If a color is marked as Optimizable, the value in brackets behind the status indicates the maximum improvement to be expected.

Step 7: When clicking the Apply button the optimized spot colors (based on the measurement data) will be calculated and applied in the Configuration. Only tick the checkbox Iterate all Spot Colors if you would like to iterate all spot colors. We recommend to deactivate the checkbox in order to include only those spot colors in the iteration which can actually be improved. Consequently, if the checkbox is disabled, spot colors which are already marked as Good in the report will not be optimized further.

A feedback message informs the user when a spot color iteration has been applied successfully.

You will find the optimized device values (Output values) in the table of the tab Spot Colors under Configuration. They will be marked as Iterated in the column Information of the table. 

Expert tips: It is a good idea to Export the optimized spot color table of the tab Spot Colors. This will give you the chance to revert to these values in case you do some further iterations or change some values manually. Another tip in case you would like to revert to the original values without iteration is to use the Reset button in the Spot Color Iteration dialog. This deletes the iterated colors from the table.

Additional information

If you would like to evaluate the improvements in terms of deltaE2000 after Step 7 you need to print the optimized spot colors once more. To do so click on the Save button  in Step 3 of the Iterate Spot Colors dialog to create a new test chart file with the optimized device values and a new reference file. Make sure to use the second  testchart file when printing and measuring rather than the first one! After measuring and saving a new Report you can assess the improved deltaE00 values. You can continue to iterate by simply clicking the Apply button in Step 7. Or, in case the deltaEs are fine and further iteration is not recommended, simply close the dialog without applying the new measurements.

If the selected source file does contain spot colors which have not been considered in the selected configuration, an error message will appear as the test chart cannot be created. For that reason we recommend to convert the source file containing the spot colors integrating the wanted configuration prior to the iteration, or to verify them using the Spot Color Report in order to ensure correct settings in the configuration.

If you would like to optimize the creation of the test chart for you measuring device (for Step 3 of the iteration) you can create your own settings using the tool Export Chart in ColorAnt. The newly created settings are available in the drop-down menu Instrument Setting after the dialog Spot Color Iteration has been closed and reopened.

The measurement data that has been transmitted from Measure Tool to ZePrA in Step 5 is saved for later use in the shared folder for all users under ColorLogic/SpotColorMeasurements (Windows: C:\Users\Public\Documents\ColorLogic\SpotColorMeasurements. Mac: \Users\Shared\ColorLogic\SpotColorMeasurements).

ZePrA | Applying Correction DeviceLinks

Correction DeviceLinks

Modify target profiles with updated profiles or correction DeviceLinks

Apply Correction DeviceLink Profile

The more reliable the color behavior of your press and the more accurate the associated ICC profile for the printing process, the better the color conversion with ZePrA. In practice, however, things often look different. Fluctuations between paper batches, varying tonal value increases or fresh printing inks deviate from the ink series last used, which leads to color deviations and differences in the tonal value distribution.

To compensate for these fluctuations and deviations, CoPrA SP* with its Update Profile module is part of ZePrA’s SmartLink module. Instead of generating a completely new press profile and DeviceLink profile in case of deviations, a correction DeviceLink profile can be used to adapt to the changed conditions.
Very little information, such as the spectral measurement values of dot gain strips or, even better, of the Reprofiler measuring strip provided by CoPrA SP*, will ensure that your press produces the same color impression as before the deviation.

The Correction DeviceLink profile will be applied after the color conversion defined in your configuration. So you can continue to use your tested and proven DeviceLink profiles and do not have to replace them due to a change in the target color space of your press.

Note: *SP = Serialized Profiles. The profiles created with CoPrA SP are encoded with the serial no. of the ZePrA color server and can only be used there.

Update/correct the target profile in CoPrA

CoPrA’s Update Profile module allows existing ICC profiles to be updated with a few measurements. Correction DeviceLink profiles based on updated profiles can optionally be created for application on print data. These profiles can be selected in ZePrA under Configurations in the Document/Target tab by activating the Apply Correction DeviceLink Profile checkbox in the Target Color Space control panel. ZePrA versions prior to 4.6.2 do not support this profile type.

Procedure

  1. Select a measuring strip. CoPrA contains two Reprofiler measuring strips for different measuring devices for CMYK and RGB-based printing systems. For other color spaces, ColorAnt can be used to create suitable measuring strips.
    (1) The Reprofiler measuring strip small is available in a one-row and a two-row version. The one-row version can be placed more easily in the trim area of a printing press. The two-row strip is more suitable for digital printing or inkjet systems.
    (2) The Reprofiler measuring strip large contains considerably more color patches and is therefore better suited for optimizing larger color variations, as well as in digital and inkjet printing.
    Note:Besides the included ColorLogic measuring strips, other measuring strips can also be used, for example Ugra/Fogra Media Wedge, IDEAlliance Media Wedge, ECI GrayControl Strip, ECI bvdm TVI or UGRA UDKS Wedge. Alternatively, you can use an existing measurement file that reflects your current printing conditions.
  2. Print the measuring strip. To do this, deactivate the color management settings, i.e. no simulation of a printing condition will take place. This is especially true for digital printing systems.
  3. Measure the measuring strip with a spectrophotometer.
  4. The Update Profile tool in CoPrA optimizes the ICC profile of your target profile (= printer profile selected as Target Color Space in ZePrA).
    Note: If you use the Apply Correction DeviceLink Profile function, you do not need to replace the profile set as the target color space because this is done elsewhere – see below. 

Applying the correction DeviceLink profile in ZePrA

  1. In Configuration, Document/Target click the checkbox Apply Correction DeviceLink Profile. If there are no correction DeviceLink profiles, the option is grayed out.
  2. Click Settings to open the Correction DeviceLink Profile dialog and select a correction DeviceLink that has previously been created by CoPrA.
  3. The corresponding optimized target profile should also be embedded in the converted file (Embed updated Target Profile instead of the Target Profile). This will make this profile the new Output Intent of the converted PDF file. The updated target profile is shown below.
    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.

ZePrA | Spot color processing

Spot Color Processing

The spot color module of ZePrA allows spot colors of PDF files to be converted accurately into CMYK, RGB or Multicolor color spaces. It requires a spot color license, which is included in ZePrA XXL, but can also be purchased as an Add-on module.

The spot color module

  • is part of ZePrA XXL, including a Multicolor license.
  • is available as an Add-on for ZePrA (requires a spot color license).
  • is part of the Multicolor Add-on (requires a Multicolor license).

Spot Color Libraries

Spot Color Libraries and spot colors can be clearly managed in ZePrA’s spot color module. It can be opened with a click on Spot Color Libraries in the sidebar.

Here libraries can be created, added, viewed and customized. Individual spot colors can be edited, imported or measured. For example, spot colors from color fans can be measured with a spectrophotometer or Lab values can be entered manually. Color tables with spot colors can also be imported. Supported formats are Named Color ICC profiles, Photoshop ACO color tables, Adobe ASE color tables (from InDesign or Illustrator), text files in CGATS format or CxF files, such as CxF/X-4. You can import your PantoneLIVE color fans stored in the cloud using the PantoneLIVE button.

Note: PantoneLIVE® from X-Rite is a cloud solution for digital storage of spectral spot colors. For using PantoneLIVE, licenses for the spot color module of ZePrA and for PantoneLIVE from X-Rite are required. Under My X-Rite you must unlock your licenses for use in ZePrA. For information on how to do this, see PantoneLIVE.

Both Lab and spectral color values are supported. Spectral measurement data are to be preferred, as they give the best results internally.

For more information about spot colors and spot color libraries, see:

Spot Colors

Edit Spot Color

PantoneLIVE

Converting spot colors to pixel-based formats: Spot colors from image files (ZePrA supports the pixel formats TIFF, PSD and PSB) can be converted by generating the spot colors as alpha channels with spot color attribute.

Without spot color module: The alternative replacement colors specified in the PDF file are used to convert spot colors to the target color space, resulting in reduced quality. For more information, see Working without the Spot Color Module.
Note: In many cases, standard conversion without the use of a custom spot color library will not result in a sufficiently good spot color reproduction or a good printing replacement process color.

Retain user-defined spot colors: Maintaining custom spot colors is critical to print production. For example, in packaging printing, this is necessary to preserve areas for die cut, braille, varnish, fold and crop marks.

Spot Color Processing – The Classic Method

Normally, spot colors (DeviceN colors without CMYK components) are resolved and converted into the target profile. The replacement color (Alternate Color Space or replacement color in the PDF) that is assigned to each spot color in the PDF is used. The PDF alternate color space for a spot color is usually specified in CMYK or Lab and is specified in the PDF-creating graphics or layout application (for example Adobe Illustrator, InDesign or QuarkXPress).

By using the appropriate settings, ZePrA performs a DeviceLink conversion from the replacement color to the target color space. Nevertheless, conversion with the replacement color value is a rather inaccurate solution, especially if the replacement color for the spot color is specified with device-dependent CMYK values. But even if the replacement color is defined by a measured Lab value, the ICC color conversion results in a color conversion that is mostly not sufficiently accurate and above all not well printable.

Example: The spot color PANTONE 266 C of a PDF document has an alternate color value of CMYK = 70/81/0/0. Printed in high-quality offset printing on coated paper according to ISO Coated V2, these CMYK process color values would produce a dark violet color that is 32.7 DeltaE-76 or 9.8 DeltaE-2000 away from the actual spot color (see screenshot). The color lies outside the printable color gamut and is therefore not printable in four-color offset printing.

The same spot color with the same PDF replacement color value would also only be reproduced with a large color error of approx. 9 DeltaE-2000 in a Multicolor printing system with 7 colors, which could simulate the spot color very well. In our example, a conversion via a stored CMYK replacement color value will therefore lead to an extremely unsatisfactory color reproduction in both printing processes.

Working with spot colors

An exact conversion of spot colors requires color libraries with correctly measured spectral color values on the one hand, and additional DeltaE minimization on the other. With a DeltaE minimization, our example colour PANTONE 266 C in the Multicolor 7C printing process could even be reproduced exactly without color errors (see screenshot).

Often several Spot Color Libraries are created for identical spot colors because it is necessary to use separate and optimized color values for different substrates or printing processes.

Spot Color Libraries can use measured gradations of spot colors, so that gradations of the spot color can be reproduced optimally (for example, the 50% value of a spot color).

In order to better calculate overprint simulations, the measured values can be stored spectrally (also spectrally on black color). Then the calculation is done with an intelligent spectral color mixing model.

ZePrA is able to maintain overprinting properties if this is possible.

For elements consisting of a mixture of spot colors and other process colors, the color appearance is simulated in the best possible way after the spot color has been resolved.

When converting to the target color space, as few process colors as possible can be used while still maintaining the smallest possible visual color difference. In our example, the optimal solution is to use only the violet process color (see screenshot) and still achieve a color error of only 1.0 DeltaE-2000.

Spot colors can be converted to a desired target value (for example, a process color) regardless of the smallest possible DeltaE. This is necessary for texts or barcodes, among other things.

Spot colors can be excluded from a conversion, for example when spot colors are used as crop marks, gloss varnishes or braille characters.

ZePrA | Working with Transparencies

Working with Transparencies

Working with Transparencies

Transparency Flattening and Sharpening

Many users often think of only photographic images when sharpening PDF data.  However, when flattening transparencies, vectors and texts can also be converted into pixel-based images. These pixel-based images are treated like photos when the Sharpening option is activated This can lead to adverse results. A difference in sharpness between adjacent objects in the form of a vector or text can cause visual issues and inconsistencies. For production, sharpening effects should always be tested in advance.

Use caution when flattening transparencies with ZePrA. Sharpening takes place before conversion and flattening. In contrast, sharpening without transparency reduction in ZePrA takes place after conversion.

Depending on the composition of the elements in the layout software on the one hand, and the parameters for flattening the transparencies and sharpening in ZePrA on the other, extreme sharpening can produce visually undesirable effects.

The negative effects only become apparent at the most extreme sharpening Amount with a Threshold of 0. Since JPEG artifacts usually show minimal color differences, a high Threshold is the most important factor to avoid unwanted effects.

The following example shows the effects of different sharpening levels. In this case, the graphic designer has placed an object with drop shadow over a gradient.

When flattening the transparencies, the flattened elements were compressed using the JPEG format. With an extreme sharpening setting, the artifacts part of the gradient underneath the drop shadow, which is usually invisible, become intensified when converted into a JPEG image. The following sharpness settings were used from top to bottom:

  • No Sharpening
  • Radius 0.35 points, Amount 80, Threshold 8
  • Radius 0.35 points, Amount 300, Threshold 4
  • Radius 0.35 points, Amount 500, Threshold 0

 

Converting PDF files containing transparencies

When converting PDF files with transparencies, the transparencies can either be preserved or flattened using Transparency Flattening.

During conversion, each object – with or without transparency – is converted separately, preserving the structure of the PDF document.

Unfortunately, there are so many variations in the blending of transparencies and the stacking order of semi transparent objects that there is no simple rule as to when transparencies ought to be flattened or not.

Flattening requires the resolution of the platesetter to be specified; therefore, it is best to perform transparency reduction as late as possible in the workflow.

ColorLogic recommends performing the conversion in ZePrA first without transparency flattening and then to check the converted file with a transparency-compatible PDF viewer (e.g. Adobe Acrobat Pro or Callas PDF Toolbox). If the converted file is visually correct and the desired total amount of coverage is maintained, continue working with the file.

If the file contains artifacts after conversion, uncheck the Convert all transparent Elements in PDF Files checkbox under Configurations/PDF and convert the file again.

This changing this setting often helps to preserve the impression of the original file (see figure below), since ZePrA excludes certain transparency modes from the conversion.

The checkbox Convert all transparent Elements in PDF Files is active by default.

However, if there are still artifacts after deactivating this function, use Transparency Flattening.

Note: Transparency Flattening is based on the Callas SDK, which in turn uses Adobe’s PDF engine for transparency flattening. Therefore, the results achieved with ZePrA’s Transparency Flattening are identical to those achieved with the current versions of Callas pdfToolbox.

Converting Spot Colors containing Transparencies

For transparency flattening of PDF files containing transparent objects composed of process and spot colors, Adobe’s transparency flattening preserves spot colors to preserve the impression of the original but sets them to “Overprint”. Transparency-reduced PDF files should therefore always be viewed with “Overprint preview” enabled in the PDF viewer (e.g. Adobe Acrobat Pro). Simple PDF viewers, such as the Preview in macOS, or many apps on tablets, display such files incorrectly due to the missing overprint feature.

If ZePrA is to be used for high-quality spot color conversions instead of the PDF preflight program or the RIP, activate the checkbox Convert Spot Colors under Configurations/Spot Colors and spot colors are converted to process colors in the best possible way.

Note: Spot colors that are converted will be set to “Overprint” due to the transparency reduction and can mix with process colors. This can lead to unwanted results and the disappearance of converted spot color objects. If this happens, select Transparency Flattening and either Dissolve Overprinting or use the extreme method Rasterize Document.

Transparency Flattening, Image Quality, and File Size

When reducing transparencies, the resulting rasterized objects are created with lossless ZIP compression. This guarantees the best quality but also results in larger files compared to JPEG compression. Even PDF files with JPEG-compressed images will have ZIP-compressed images due to transparency flattening. If the file size is to be reduced, and a reduced quality is acceptable, change the Compression Method to JPEG (in the Image Quality panel under Configurations/Options).

Note: The Compression Method is only considered by ZePrA when performing a conversion. When performing a Transparency Flattening without conversion, no compression change is made, and rasterized objects are ZIP-compressed.