ColorLogic's PSOcoatedv3_GCR_ColorLogic.ICC

The creation of a Linearization DeviceLink starts with printing a linearization test chart on the uncalibrated printer without any color management.

There are two ways to get the necessary measurement data for the creation of a Linearization DeviceLink profile:

1. Measure the test chart and optimize the measurement data using appropriate software, such as ColorAnt (using the tools Custom Chart and Export Chart) and open the measurement data in CoPrA’s Linearization module.
2. Measure the linearization test chart by using CoPrA’s own Measure Tool.

Load: Opens and displays existing measurement data files. Alternatively, drag and drop the data into the window, to extract and view the data.

Measure: Opens the Measure Tool to measure the linearization test chart with a supported device.

Chart preview area: The preview of the reference data of a linearization chart shows the correct colors. This allows for a visual comparison of the reference and the measured data.

Note: When previewing the reference data of a chart with White ink, the correct color of the white point is displayed.

Setting: Select the linearization method. CoPrA contains three [PREDEFINED] settings (Default, Flexo Linearization, G7 Linearization). These settings can be [EDITED] and [SAVED].

Customize: Allows fine tuning of the linearization setting by selecting the Calculation Mode and adjusting the Protect Lights (%).

Fit to Width: Fits the color patches of a row to the window width. Especially for large test charts with very many color patches and many rows the color patches will be displayed larger.

Show reference data: The device values such as CMYK or Multicolor and measurement data (i.e. Lab or spectral values) are shown on a split color patch. The data can be quickly compared for incorrect or faulty data.

Calculation Mode: This setting defines the method to calculate the colorimetric linearity. Six standard methods are available which can be customized and saved.

ColorLogic Default (colorimetric linearization): Linearizes the curves based on Lab/dE-76 which means that a 50% value of a primary has the same distance to the left (white) as to the right (full tone) and is therefore located at the midpoint of the graphic.

Linearization according to ISO 20654: Linearizes the tone values of primary gradation ramps based on linearity according to ISO 20654.
Note: The methods ColorLogic Default and Linearization according to ISO 20654 are very similar. However, in contrast to the ISO 20654 approach, ColorLogic Default takes the hue of primaries into consideration.

Linearization according to G7 (CMYK only): The CMYK tone value curves are linearized to match the gray balance requirements of the G7 calibration process. Additional Multicolor channels are not affected.

Linearization according to G7 (CMYK) and ISO 20654 (spot colors): G7 is defined to work with CMYK only. The additional Multicolor channels are not affected. Therefore, activating this setting applies the G7 procedure to the CMYK parts of a Multicolor measurement file and the ISO 20654-based method to the remaining Multicolor channels.

ColorLogic Default (colorimetric linearization) with automatic channel limit: Same as ColorLogic Default (colorimetric linearization), but with enabled ink limiting function. See note below for more information.

Linearization according to ISO20654 with automatic channel limit: Same as Linearization according to ISO20654, but with enabled ink limiting function. See note below for more information.

Ink Splitting: Allows the creation of ink splitting linearizations by automatically combining light and full ink channels. This minimizes the number of channels used in subsequent profiling.

Currently, only the combination of light and full color channels is supported (not e.g., the light light gray –> light gray –> full ink-splitting).

Note: InkSplitting linearization curves are included in the Linearization Profile Report and can be analyzed in more detail there.

Note on ink limiting for Linearization DeviceLinks

Ink limiting during linearization is necessary if ink channels are saturated and do not provide sufficient differentiation between the individual color values at higher ink densities. This is typically done by printing a step wedge and then visually determining the percentage up to which a good differentiation exists. The ink channel is then limited at this value. We have added an automatic channel limit function that does exactly this based on the saturation values of the measurements. This function has been added to the two calculation modes ColorLogic Default and Linearization according to ISO20654.

Note: For the G7 mode the channel limit function has not been made available as this would contradict the G7 linearization methodology. Ink limiting should be done before applying G7.

Protect Lights (%): Protects highlight areas. Values below the set percentage are protected and will not be linearized. Make sure to get a smooth transition from the protected – non-linearized – highlights to the linearized part of the measurement data.
Note: For linearization of the entire measurement data, set the slider to 0.

The curves graphic allows assessment of the linearization results based on the selected settings. Use the two radio buttons to compare the Calculated Curves – which will lead to a linear behavior of the printer when applied – to the original CMYK and Multicolor curves (Curves from Data).

Calculated Curves: Represent the curves based on the selected settings that will be applied in the resulting Linearization DeviceLink profile.

Curves from Data: Shows the original non-linearized curves. The graph is a colorimetric representation of the curves according to ISO 20654. Linear curves indicate a printer in a perfectly calibrated state according to ISO 20654.

Click Next and define the profile settings. Generate a Profile Report to get all important details about the DeviceLink profile.

Note: The generated Linearization DeviceLink profile can be used in a workflow for any kind of printing process. For example, it should be used when printing a profiling test chart on an uncalibrated printer. ColorLogic ZePrA supports the use of Linearization DeviceLinks as gradation curves. This way the linearization can be applied to a workflow like curve corrections in a RIP. In this case, curve corrections must be disabled on RIP level to avoid double changes.

Name: Enter a name for the profile.

Templates: Allows to select and combine name components from a list of options and save them as custom templates. The last selected template is used when creating new profiles, so the naming of profiles is automated. 

Available naming options include Date, Date/Time, Measurement data file name, Source profile, Name of the current preset and others. Each name component can be added at a user-defined position under Template (select the position with the mouse pointer). The Example section below shows the resulting name. Additionally, user defined text can be added at any position within the Template field.

Format: Define the Format of the profile. If the ICC v4 format is chosen, please ensure that your programs support this format correctly.

Note: ColorLogic products handle and use ICC v4 profiles consistently and correctly.

Size: The size typically specifies the number of grid points in the profile. However, for linearization DeviceLink profiles they are of no relevance as only TRCs (tone reproduction curves) are generated.

The two options Small and Large affect the number of data points saved in the ACV and XML formats. Small creates 11 points for ACV and XML while Large creates the full flavoured 51 points for XML and 16 for ACV. The size does not affect the ICC DeviceLink profile created as it always uses the highest precision.

Further processing

Optionally, linearization curves can either be saved as Photoshop ACV files or as XML files according to the format definitions in ISO 18620:2016.

Save curves as Photoshop ACV format: Linearization curves, saved in the Adobe Photoshop Curve format (ACV), can be imported in Photoshop and applied to images.

Save curves as ISO 18620:2016 XML format: ISO 18620:2016 specifies a simple extensible XML format for the exchange of tone adjustment curves between applications including but not limited to color management, calibration and raster image processor systems. Some RIPs such as Esko Colorpilot support this format, which allows importing and using the high-quality curves generated by CoPrA.

Note: The curves are saved with the same name as the ICC profile in the User/Documents/CoPrA/Linearization folder.

Create Profile Report: Recommended to activate. The PDF report provides an overview of the quality of the profile. It contains general profile information, color generation information, profile statistics, correction curves and graphics that take into account the different calculation modes of the linearization options which are dynamically included in the report.
Under Preferences, the Default save path for the reports and the Default report format can be selected. If XML is selected as the format, the corresponding XSD files will be created automatically as well.

When creating a Linearization according to G7, the report shows the tonality/gray balance, the different NPDC curves before and after the calculation and the G7 evaluation based on the measurement and calculation data. The same applies to the various linearity curves such as ColorLogic Default (Colorimetric Linearization) or according to ISO20654.

By using different categories, it is easy to check whether a limit has been exceeded (red values) or not (green values).

Depending on the type of profile the report contains various statistical data, such as statistics about profile precision (Integrity, Precision, Black Point, White Point etc.), graphic representations of curves and gamuts (Gray Balance, Gradients etc.), conversions of test images, separations and color patches to evaluate the smoothness or the purity of colors. All this facilitates the detection of artifacts that may be present.

Profile reports can be created at any time in Batch Overview or in Profile Manager which, by the way, is not restricted to ColorLogic profiles.

Under Preferences you can define some basic settings for the creation of the profile report, such as the file location, the report format (PDF or XML) or the DeltaE method (dE76 or dE2000).

If the checkboxes Brightener Compensation or Measurement Correction have been activated, the data of the original profile will not be compared to the measurement data from the update test chart but to the data modified by these options.

1. Open the tool SaveInk and select the printer profile to use for the creation of a SaveInk profile.
   Note: All profile drop-down menus function like search fields. Simply type in some letters of the desired profile and only those profiles containing these letters will be shown in the list. To select a profile simply click on it.
   Alternatively open the drop-down menu with the little arrow on the right and select a profile from the full list as usual.
2. Select a predefined Setting for the SaveInk calculation from the drop-down menu.
   

   Predefined settings for SaveInk profiles

   
   

   SaveInk Settings

   Default: Use this setting as a starting point, if other presets are not suitable for your print process.

   Extreme: Highest ink saving, but with slight visual flaws to the original.
   Note: This preset may reduce Secondaries, Duplex and Triplex colors if ink can be saved. If you explicitly want to maintain 200% inks for red, green and blue tones, you should use the slider to reduce the dE-Tolerance instead.

   Maximum: Maximum color savings with colorimetric accuracy still very high while maintaining the visual color impression. The colorimetric accuracy is best with a dE-Tolerance of 0. This setting requires experienced printers and an excellent command of the standardization.

   SaveNeutral Gravure – SaveNeutral Offset TAC 300: Use these settings for gravure or offset printing. These settings moderately increase the black content in neutral color areas. This is ideal for print shops who are looking for a quick introduction to saving ink and want to gain practical experience. These profiles are mainly used to stabilize the printing process and are less suitable for saving ink.

   SaveStrong Gravure – SaveStrong Offset TAC 300: Use these settings for gravure or offset printing. They greatly increase the proportion of black and are aimed at printers who have their printing process under control according to the standardization and who want to achieve high ink savings, but still want to leave room for adjustments on the press.

   TAC-Limit300 – TAC-Limit220: TAC-Limit profiles do not perform any color conversion and limit only the total amount of color without strongly interfering with the color composition. Use TAC-Limit300 for offset printing and TAC-Limit220 for newspaper printing, for example.

3. Customize allows you to specify the Method, the Total Amount of Color, the Ink Saving and to define Exceptions.

Method

There are two methods available to specify the basic settings for Ink Saving – Standard and Advanced.

Standard: Reduces the settings a user needs to define to a minimum but still achieves economical high quality profiles. Only three settings have to be adjusted: the Total Amount of Color, the Ink Saving slider and the exception Preserve 0% Black. Use this method to get quick results.

Advanced: Allows the user to also define Black Start, Black Width and Exceptions. Use this method to define more precisely how the ink saving performs. When selecting the same settings as in the standard method it will produce identical results.

Total Amount of Color for SaveInk Profiles

The feature Total Amount of Color allows the tonal value limit to be set for your SaveInk profile. Print data which are converted using the SaveInk profile will be limited to the total area coverage set in the profile. The maximum black value is controlled and adjusted automatically.

Use Mode to specify whether the total area coverage and the maximum black value are to be adopted from the Profile, will be defined manually using Custom or will be calculated automatically using Auto. The maximum black value, the total area coverage and the darkest L* value will be calculated according to the selected method and will be displayed after a short processing. These values reveal, for example, whether a reduction of the total area coverage will result in brightening of the shadows. Brightening can be identified by an increase of the L* value.

Notes:

1. In most cases, the mode Auto produces the best results. Assuming the printer profile allows it, it will calculate a slight reduction of the total area coverage without increasing the L* value significantly.
2. When using the methods Maximum or Extreme while strongly reducing the total area coverage as well, an identical Lab measurement mapping is possible only to a limited extent.
3. If the TAC is below 200% the exception Preserve Secondaries is available.

Ink Saving

Ink Saving: Defines the replacement of composite black (CMY) by pure black. The higher the slider setting, the more colored ink is replaced by pure black. So higher slider settings achieve higher ink savings, but at the expense of the colorimetric accuracy.

Black Start: Defines the starting point for the replacement of composite black (CMY) by pure black. Pure black will be used above the entered value.

Black Width: Defines the range in which black is used outside the color-neutral area. The higher the value, the more black will be used outside the color-neutral area.

dE Tolerance: Allows tremendous ink savings when set to a high dE tolerance. Increases the maximum deltaE between the original profile and the SaveInk DeviceLink profile which results in greater ink savings. In contrast, the predefined settings SaveNeutral, SaveStrong and Maximum use a low dE tolerance setting of 0 deltaE ensuring a very high color and visual accuracy of the profile. However if greater ink savings are desired it can only be done by reducing the visual accuracy, hence a higher dE tolerance setting is required. The ink saving preset Extreme uses a high dE tolerance.

Note: Users can save on ink even more by using a higher dE tolerance setting. We recommend to test ink saving profiles with high dE tolerance settings closely before using them in production.

Exceptions in SaveInk Profiling

Exceptions define the colors to be excluded from ink saving when creating SaveInk profiles.

Preserve 0% Black: Areas which are built with CMY only (without black) remain unchanged by the SaveInk optimization. This is particularly important when overprinting with CMY colors but results in a considerably reduced ink saving.

Preserve Secondaries: Is only available when the total area coverage (TAC) is set to values below 200%. It allows to obtain highly saturated secondary colors without reduction, although the total area coverage is reduced below 200%.
There is a tendency in current newspaper printing and high-speed InkJet printing to use a TAC of less than 200%. This may result in an unwanted reduction of secondary colors (those who need at least 200% ink) and thus result in washed out colors. Total area coverages over 200% always preserve secondary colors, however, without this exception a reduction below 200% would also reduce red, green and blue tones. This can be avoided by activating this exception as it ensures that full red, green and blue tones remain unchanged while the TAC of dark colors and of the black point is deceased below the set total area coverage of 200%.

Preserve Skin Tones: Excludes skin tones from ink saving. This is an approach especially important for printing systems with coarse raster frequencies (for example, large format InkJet systems with low resolution, newspaper printing or printing processes subject to the ‘Missing Dot’ problem) to reduce the so called peppering effect, visual graying or troubled skin tones.

Note: Exceptions to Preserve Skin Tones and Custom exceptions are not available for Multicolor profiles and are grayed out.

Custom: Specify individual CMYK color values to be excluded from ink saving. These could include specific company colors or corporate identity colors that must remain unchanged. Select Edit to open a window where the CMYK color values can be entered that will be excluded from the SaveInk optimization.

Define Custom Exceptions:

1. New creates an entry for a new color.
2. Under Value, enter the CMYK value to be excluded from SaveInk conversion. Optionally, assign a name for this color.
3. Enter as many colors as required.
4. Activate the checkbox Enabled to select the colors to be excluded.
5. Click OK to confirm these values.
6. Make sure to enable the checkbox Custom.

Name: Type in a Name for the profile.

Templates: Allows to select and combine name components from a list of options and save them as custom templates. The last selected template is used when creating new profiles, so the naming of profiles is automated.

Available naming options depend on the current profile type and include Date, Date/Time, Measurement data file name, Source and Target profiles, Name of the current preset and others. Each name component can be added at a user-defined position under Template (the position is selected with the mouse pointer). The Example section below shows the resulting name. Additionally, user defined text can be added at any position within the Template field.

Format: Define the Format of your profile. An ICC format in accordance with specification v2 is recommended as basic setting however, the newer format ICC v4 can also be chosen. In this case, please ensure that your programs support this format correctly.
Note: ColorLogic products handle and use ICC v4 profiles consistently and correctly.

Size: The setting Large is recommended. The size specifies the number of grid points in the profile and determines the amount of disk space required for the generated profile. Small profiles should only be used for test purposes. Very Large profiles can slow down further processing in subsequent programs. Additionally, some programs are not able to handle very large profiles.

Further processing

Create Profile Report: Recommended to activate. The PDF report provides an overview of the quality of the profile based on statistics, diagrams of gray balances, gradients and gamut representations as well as color separations of converted test files.
Under Preferences, the Default save path for the reports and the Default report format can be selected. If XML is selected as the format, the corresponding XSD files will be created automatically as well.

Embed profiles: Physically incorporates the used source and target profiles into the DeviceLink. This function is tricky and only recommended if the DeviceLink has to be transferred to a computer which does not have the required source and target profiles. It was implemented mainly for use with certain RIPs which only accept DeviceLinks with embedded source and target profiles.

Save: Creates the printer profile and saves it in the folder Profiles (macOS) or Color (Windows), (macOS: /Users/Username/Library/ColorSync/Profiles, Windows: C:\Windows\System32\spool\\drivers\color). Demo and encrypted profiles will be saved in a different location only relevant for ColorLogic applications.

Note: CoPrA-SP profiles are stored in the ColorLogic subfolder Licensed-Profiles.

Profile reports can be created for Printer or DeviceLink profiles. To do so, activate the checkbox Create Profile Report in the last step of the profiling or, when updating profiles, the checkbox Create Profile Comparison Report.

Depending on the type of profile the report contains various statistical data, such as statistics about profile precision (Integrity, Precision, Black Point, White Point etc.), graphic representations of curves and gamuts (Gray Balance, Gradients etc.), conversions of test images, separations and color patches to evaluate the smoothness or the purity of colors. All this facilitates the detection of artifacts that may be present.

Profile reports can be created at any time in Batch Overview or in Profile Manager which, by the way, is not restricted to ColorLogic profiles.

Under Preferences you can define some basic settings for the creation of the profile report, such as the file location, the report format (PDF or XML) or the DeltaE method (dE76 or dE2000).

Note: If a profile comparison report is created when updating a profile, the measurement data obtained from the update test chart will be compared to the data of the original profile (reference profile).

If the checkboxes Brightener Compensation or Measurement Correction have been activated, the data of the original profile will not be compared to the measurement data from the update test chart but to the data modified by these options.