ColorLogic’s Printer Profile PSOcoatedv3_GCR_ColorLogic.ICC explained

PSOcoatedv3_GCR_ColorLogic.ICC profile

ColorLogic’s Printer Profile ‘PSOcoatedv3_GCR_ColorLogic.ICC’ explained

PSOcoated_v3_GCR_ColorLogic vs. PSOcoated_v3

Tutorial: ColorLogic’s Printer Profile ‘PSOcoatedv3_GCR_ColorLogic.ICC’ explained


Optimized Printability for neutral Image Areas

This profile is an alternative to the ICC profile ‘PSOcoated_v3‘ from the ECI. It is based on FOGRA51 characterization data and offers optimized printability for neutral image areas.

Details on PSOcoatedv3_GCR_ColorLogic.ICC

Good printability in offset printing requires optimized GCR settings (Gray Component Replacement) and a fine-tuned balance of K and CMY in separated images. When RGB images are converted to CMYK using ICC profiles the GCR settings are fixed in the CMYK printer profile and specified during ICC profile generation.

The example below shows a comparison between the GCR settings of the ECI profile ‘PSOcoated_v3.ICC’ and ColorLogic’s alternative profile:

The two main differences in regard of GCR settings of our ICC profile ‘PSOcoated_v3_GCR_ColorLogic‘ and the ‘PSOcoated_v3‘ profile from the ECI are:

1) Neutral images are printed more stable: Maximum GCR in neutrals

The original ECI profile features a medium GCR which is similar in both neutrals and skin tones. In contrast, ColorLogic’s profile has a maximum GCR in neutrals but is reduced in tertiary colors like skin tones. This GCR strategy combines the best of both worlds: A maximum GCR for neutral colors to prevent color casts as far as possible or unstable gray balances during printing. A medium GCR for skin tones to prevent grayish skin tones in case black is printed too strong.

2) More stable printability for light image areas: Black starts at zero

When using ColorLogic’s profile, black starts at zero and replaces similar CMY values. This stabilizes areas of light neutral colors. RGB images which contain neutral vignettes or drop shadows from gray to white will be printed more stable.

Links and Downloads

 

ZePrA | Spot color processing

Spot Color Processing

ColorLogic’s spot color solution is aimed at printers whose customers impose stringent demands on the color accurate rendering of spot colors. Packaging printer that process files with many different spot colors looking to optimize their printing process by converting spot colors into CMYK or Multicolor process colors. The ColorLogic solution offers printers the security of getting the best possible conversion of spot colors to process colors, in terms of colorimetry and printability.

Classic methods of spot conversion

To appreciate the special features of the new solution, we first need to take a look back in order to understand how the previous method for converting spot colors used to work in ZePrA and many other solutions: The Convert spot colors to target color space checkbox resolves spot colors (DeviceN colors without CMYK components) and converts them to the target profile. The substitute color (referred to as the alternate color space in the PDF) assigned to each spot color in the PDF file is used in this context and is processed using the color management settings in the Images/Vectors tab in ZePrA. The PDF alternate color value for a spot color is usually indicated in CMYK or Lab, and is specified in the graphic or layout application used to create the PDF (e.g. Adobe Illustrator, InDesign or QuarkXPress).

Given appropriate settings, ZePrA performs DeviceLink conversion from the alternate color space to the target color space. Nevertheless, conversion using the alternate color value is only an inaccurate solution, particularly if the alternate color for the spot color is indicated by device-dependent CMYK values. Even if the alternate color were to be indicated by a measured Lab value, ICC color conversion would usually result in converted colors that are not sufficiently accurate and, above all, not easily printable.

Example: The spot color PANTONE 266 C has an alternate color value of CMYK = 70/81/0/0 in a PDF document. When printed in a high-quality offset process on coated paper in accordance with ISO Coated V2, these CMYK process-color values would produce a dark violet color that is 29.2 Delta E-76 or 8.0 Delta E-2000 off the actual spot color (see screenshot). The color is outside the printable gamut and thus cannot be printed by 4-color offset printing.

On a Multicolor printing system with 7 process colors, which would be capable of wonderfully simulating the spot color, the same spot color with the same PDF alternate color value would likewise only be reproduced with a major color error of approx. 9 Delta E-2000.

Using this example, conversion via a stored CMYK alternate color value will result in highly unsatisfactory color reproduction in both printing processes.

Other types of approaches on the market

Lab alternate color values have been stored for spot colors in the PDF document since the launch of Adobe InDesign CS6. At first glance, Lab alternate color values appear to be a better alternative than CMYK alternate color values, but it creates other, sometimes even more serious problems when converting spot colors.

The screenshots (image) show how differently a spot color can be converted to CMYK with a Lab alternate color value. The spot color PANTONE Cool Gray 7C is highlighted in red in the original file in the screenshot on the left. The screenshot in the middle shows that conversion of this spot color by means of a standard tool leads to four process colors, which is highly unsuitable for printing. In contrast, the screenshot on the bottom right shows that conversion using ZePrA not only achieves the most accurate color reproduction, but also manages with the minimum number of channels (only the process color Black is used). Moreover, the screenshots (image)show that the spot color gradients converted with ZePrA have a far purer color appearance than the gradients converted using the standard tool.

Instead of alternate color values, other color server solutions on the market use a color library that contains the color values of the solid tones of the spot colors, measured in Lab. Rather than using the PDF alternate color value when converting spot colors to the target profile, these solutions take the Lab value of the solid tone from the color library and convert it to the target color space by the absolute colorimetric method. If the gamut of the target profile is large enough to be able to map the spot color, a good colorimetric match with the solid-tone value is obtained.

In our example using PANTONE 266 C, (image) this would be the case with our Multicolor printing process, and the spot color could be reproduced quite well with 1.9 Delta E-2000 (the screenshot on the right shows the color conversion that would be obtained with standard tools).

However, should the gamut of the target profile not be large enough and the spot color be out-of-gamut, only rarely would the best possible color value with the smallest Delta E be calculated, depending on the target profile used.

This is due to the inaccuracy of profiles and the Gamut Mapping used. The biggest drawback of simple colorimetric conversion is, however, that unwanted process color components can emerge (in our Multicolor process, for example, CMYK +Orange+Green+Violet = 3/3/6/0/5/0/87), impairing the quality of the printed image.

Just think of a text or a barcode that would thus be composed of several colors and be unsharp as a result of register problems when printed. At the same time, problems can arise when overprinting what were previously spot colors with process colors or other spot colors. Furthermore, a library that contains merely the measured solid tones permits only an incomplete prediction regarding the appearance of graduations of the spot colors. So, this approach is bound to fail and may, from the printing point of view, produce poorer results than converting the alternate color value by means of DeviceLink profiles, as previously done in ZePrA.

ZePrA’s Spot Color module features

Many users would like exact colorimetric conversion of spot colors. This results in a need for both, for color libraries with the correct, measured spectral color values and also for additional Delta E minimization. Delta E minimization would even make it possible to reproduce our specimen color PANTONE 266 C exactly and without a color error in the 7C Multicolor printing process (see screenshot below). (image)

Users would like to create and use several libraries, if necessary, for the same spot color because they need separate and optimized color values for different substrates and printing processes.

Similarly, the color libraries must work with measured graduations of the spot colors, so that the 50% value of a spot color, for example, can also be reproduced optimally.

To accurately calculate overprinting simulations, the measured values should additionally be stored in spectral form. Additionally, an intelligent, spectral color mixing model should be used.

It is also desirable if the color server is able to preserve overprinting properties to the greatest possible extent.

When dealing with elements consisting of a mixture of spot colors and other process colors, the color appearance should be simulated as accurately as possible following resolution of the spot color.

When converting to the target color space, the fewest possible process colors should be used, but the result should still yield the smallest possible visual color difference. In our example, the optimum solution is to use only the Violet process color (see screenshot below) and achieve a color error of just 0.8 Delta E-2000.

Some spot colors need to be converted to a specified target value (e.g. to a process color), regardless of the smallest possible Delta E. This is necessary for texts or barcodes, for example.

Similarly, some spot colors have to be excluded from conversion, e.g. cutting marks created as spot colors, varnishes or braille.

Application of Photoshop color corrections to PDF files

Colorimetrically generated DeviceLink profiles cannot be used in some applications. This is the case if, for example, a customer provides printing data and, instead of a correct proof, a print that needs to be matched as accurately as possible in production printing. If you open the printing data on a monitor with soft proofing based on the printing standard for production printing, there may be pronounced differences compared to the print provided by the customer.

Options for solving the problem: either to print outside the standard and try to adjust the specifications by using the gradation corrections in ZePrA, adjustments on the printing device or to apply Photoshop corrections to the PDF file.

Photoshop approach: has the advantage of applying standards to proof the color corrected data and have them approved by the customer. This method requires an person with Photoshop experience and CoPrA’s Edit module.(link)

The demo version of the programs allows a single test run with production data. The operator compiles color relevant objects, taken from the PDF data to be corrected in a file in Photoshop and combines the test data with the CoPrA Edit Chart. Then correct the test file on the monitor under soft proofing conditions. The edited image is loaded into CoPrA and the corrections are saved as a DeviceLink profile.

The DeviceLink profile can subsequently be used in ZePrA to correct the colors of the original PDF data. If necessary, these data can be approved by the customer on a proof before printing.

The printer can work according to a standard in the accustomed manner and reliably match the proof.

The individual steps for converting Photoshop corrections into DeviceLink profiles are described in the tutorial manual (link) for CoPrA.

ZePrA | 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.

Sharpening for in-house RGB workflows

Sharpening

(For example, in-house RGB workflows)

Sharpening Images

Optimal sharpening refers to the scaled final format of an image in the print data. The following section assumes that editing high-resolution RGB images, placing these images in the layout program, creating the PDF data, and processing the data with ZePrA are connected workflows within an application suite. The summary of these steps is referred to here as an in-house RGB workflow.

With in-house RGB workflows it is possible to work with high-resolution originals of the RGB images in the layout program and then generate a PDF/X-3 or PDF/X-4 file that also contains high-resolution RGB images. Finally, ZePrA handles the color management, the downsampling to the final resolution, and the sharpening. 

After the RGB images have been reduced to the final resolution and color converted to CMYK, a stronger sharpening than is usual for pre-sharpened CMYK images should be applied in ZePrA. To do so, select Strong Sharpening of RGB and Gray Images in ZePrA under Configurations/Options/Sharpening/Preset.

For documents that contain RGB images and already sharpened CMYK images it is recommended to limit sharpening in ZePrA to RGB images.

Note: If transparencies are used in the layout program, it is essential to ensure that there is no  transparency reduction, as RGB data is inevitably converted to CMYK if the RGB image is affected by transparent objects. Transparency reduction is mandatory when creating PDF/X-3 files, whereas transparency is explicitly allowed in PDF/X-4 files. If all RGB images are sharpened in ZePrA, the transparency reduction, should also take place in ZePrA.

Softproofing and PDF images

Softproofing PDF image files

Softproofing in ZePrA offers a true color presentation of jobs on the monitor, with overprinting elements and transparency effects also displayed correctly.

Creating a softproof:

  1. Go to the Navigation Panel and open Overview/Jobs and Queues Overview.
  2. Right-click on a job in Pending Jobs or Processed Jobs to open the context menu.
  3. Select the option Screen Preview. The file is displayed in a window.

Activate the Softproof Color Management Settings via the colored icon in the title bar of the window.

Simulation Profile: The colors will be rendered through the selected Simulation Profile to the monitor profile. As a default, the output intent that ZePrA has embedded in the processed file will be used and shown in brackets. The setting is similar to the Output Preview in Adobe Acrobat

Note: The Default Profiles on top of the dialog and the Prefer embedded Profiles checkbox are only relevant in the case that the simulation profile differs from the color spaces in the file itself.

Rendering Intent: A color conversion method (rendering intent) must be selected for calculation. Typically, only rendering intent directly from the Simulation Profile chooser needs to be selected. The rendering intents include not only the normal ICC intents and relative + Black Compensation, but also include three special ColorLogic intents:

Relative+ and Absolute+: have an impact if the black point information contained in a relative matrix monitor profile indicates that the black point is lighter than L* = 0. The softproof becomes a little darker as a result of this, which usually leads to a visually better match with a reference proof.

Relative Lightness: Based on the absolute colorimetric intent with paper color simulation. The lightness of the paper color simulation is scaled to the maximum displayable lightness of the monitor, the color of the paper color simulation and the gray balance of the softproof as a whole being preserved. This setting makes sense if the absolute colorimetric softproof is visually too dark, as is often the case in newspaper printing for example.

If there is no Simulation Profile available in the file (no profile shown in the brackets), select the desired profile from the drop down list. For rendering intent, we recommend relative or absolute colorimetric or ColorLogic rendering intents.

For monitor presentation, the monitor profile stored in system is automatically selected.

Click Apply to visually display the settings and Save to save the window with the settings and then close it. Next time the window is opened the settings will be retained.

Note: In order to select the correct softproof intent, it is generally advisable to use not only the monitor, but also a dimmable standardized light box with a reference proof for visual comparison.

Use of Multicolor profiles

Use of Multicolor profiles

Use of Multicolor profiles

ZePrA works with Multicolor printer profiles or with DeviceLink profiles that permit RGB-to-Multicolor, CMYK-to-Multicolor or Multicolor-to-Multicolor conversion.

Using Multicolor profiles in a PDF workflow

ZePrA features the option of using Multicolor profiles both as the document color space and target profile and using Multicolor DeviceLink profiles for color conversion.

Particularly in prepress work for packaging, this is an important option when image data are present in the form of an RGB or CMYK file. First, you can place RGB and CMYK image files directly in the finished document. From this, you create a PDF file and convert the complete document in ZePrA to the required Multicolor color composition for printing. Another interesting field of application is the printing of photo books by so-called HiFi color printing processes using 6 or 7 inks.

Note: An Multicolor module is license required (available in the XXL package) to utilize Multicolor functions.

When preparing the data in ZePrA, the result is known as a DeviceN PDF file, where every channel is named the same as channel name of the Multicolor target profile. DeviceN is the standard color definition in PDF for describing spot colors for print production. It offers a high degree of compatibility with the proven spot color processing functions of common application programs. The PDF files generated can usually be assessed in the Output Preview of the current version of Adobe Acrobat Professional and processed with current PDF workflow systems. Positioning of the PDF files in, and export from, current Adobe InDesign documents also present no challenges. ZePrA supports the PDF/X-5n standard, which enables the embedding of Multicolor profiles in PDF files.

When configuration is created with the Auto Setup wizard (selection of a Multicolor DeviceLink profile), the default setting is such that the Multicolor target profile is not embedded in image data, but that it is embedded as the output intent in PDF files. When a converted PDF/X file (e.g. a PDF/X-4, X-3 or X-1a file), the color converted file is changed into a PDF/X5n file.

Before using your Multicolor printer profile, which was selected under Define Configuration as the Target Color Space in the Target tab, or in the Document Color Space tab when it is  a Multicolor DeviceLink profile, verify whether the channel names and Lab color definitions have been entered in accordance with your specifications.

If the Embed into output file checkbox is activated, ZePrA uses the channel names and color definitions from the Multicolor printer profile set as the target color space when creating the color converted PDF file.

When Embed in output file is not checked, the channel names and color definitions are adopted from the Multicolor DeviceLink profile. Verify that the identical channel names and Lab color definitions in the target profile and the DeviceLink profile. With the help of the CoPrA’s Profile Manager, rename the Colorants (description of color channels) in accordance with your specifications and also enter the Lab color definitions in every Multicolor printer profile and DeviceLink profile.

Depending on the Multicolor profile used, the channel designations contained and the subsequent workflow outside ZePrA, we recommend that you test the complete workflow beforehand to make sure that everything runs smoothly.

Converting image data with Multicolor profiles

For converting image data with Multicolor profiles, ZePrA supports PSB, PSD, TIFF and JPEG files. Since the current file format specifications (as at May 2014) do not provide for embedding Multicolor profiles in TIFF, JPEG, PSB and PSD files, for image data conversion ColorLogic recommends deactivating Profile Embedding in the Document/Target tab. We recommend that image data to be converted to Multicolor should be saved as PSB/PSD files from Photoshop and then processed using ZePrA. Adobe InDesign can be used to process any PSB/PSD image files converted with ZePrA by means of a Multicolor target profile.

When converting the image data of Multicolor files, ZePrA distinguishes the following cases, which can be set in Configurations under Options/Image quality:

If the channel designations of the Multicolor target profile are CMYK+X, a TIFF file is created providing Preferred lossless format is set to TIFF.

If the channel designations of the Multicolor target profile are not CMYK, then a PSD file is created.

Note: TIFF only supports CMYK+X.

If the compression method is set to Automatic, the ZePrA will try to preserve the format or create a TIFF file. However in the case of a JPEG file or a non-CMYK Multicolor file, a PSD file is created.

Note: JPEG does not support Multicolor color spaces.