Creating a Printer Profile
Every printer profiling requires a test chart containing various color patches of the corresponding color space as a basis. There are two ways to get measurement data for the creation of a printer-specific ICC profile:
- Measure and optimize the test chart and measurement data using appropriate software, such as ColorAnt, then open the measurement data in CoPrA, or
- Measure the data in CoPrA directly using the Measure Tool.
Adding ColorAnt for measurement data processing is advantageous, to eliminate measurement errors, printing errors and other artifacts (for example inhomogeneities). Analyzing and optimizing the measurement data results in an increased profile quality which then results in improved reliability in production.
Note: For CMYK printing processes it is recommended to use the test chart IT8.7/4. For RGB printers, use test charts with many test patches (900 and more). For Multicolor profiling, either use the test charts provided by CoPrA or create test charts using ColorAnt.
Load or Measure Data
Load or Measure
Load: Opens and displays existing measurement data files. Alternatively, drag and drop the data into the Printer Profiling window to extract and view the data. CoPrA supports a variety of device manufacturer formats. Measurement and reference data can be processed three different ways:
- Use reference data provided by organizations such as FOGRA, ECI or IDEAlliance.
- Use data from a profile. Many manufacturers of profiling software save the measurement and reference files used for profiling within an ICC profile. Simply drag and drop the ICC profile to the Printer Profiling window and the data will be extracted and displayed. Alternatively, the profile can be opened and extracted using the button Load. If an error message pops up, the ICC profile does not contain measurement data.
- Measure test charts using ColorAnt or measuring tools from other instrument manufacturers, save the data and open in CoPrA.
Measure: As an alternative to working with pre-existing measurement data, test charts can also be measured using CoPrA’s Measure Tool. Open Measure Tool by clicking Measure and measure with a supported device. Further information on the measurement of test charts can be found here.
Setting: Select the applied printing method. CoPrA contains a large number of standard settings for common printing methods (e.g. digital and inkjet printing).
Customize: In order to achieve the best possible profile quality, further settings can be adjusted under Customize, such as settings for Color Generation or the specification of the first printed tone.
Fit to Width: By activating this checkbox the color patches of a row will be fit to the window width. Especially for large test charts with many color patches and many rows, the color patches will be displayed larger.
Show reference data: The device values such as CMYK or RGB 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.
Working with Profile Settings
Import, Export or Cleanup of Profile Settings
Profile settings for Printer, DeviceLink and SaveInk profiling can be selected in the drop-down menu Setting.
The package CoPrA Basic allows selection of default predefined settings. The package CoPrA M and higher provides access to all the parameters of the profile which can be customized.
To adjust these profile parameters, select Customize. Custom settings can be saved, imported and exported which provides the ability to exchange personal profiling settings easily with other CoPrA users or make them available for support purposes.
Import setting: Settings can either be imported as configuration file via the Tools menu using the entry Import setting or by dragging an ICC profile with the desired settings on the drop-down menu Setting. The name of imported profiles receives the suffix (imported). If an inappropriate profile (for example an RGB profile for CMYK profiling) is dragged on the drop-down menu Setting, an error message appears.
Export setting: Customized profile settings can be selected in the drop-down menu Setting and exported as configuration file by using the entry Export setting from the Tools menu.
However, CoPrA's default settings cannot be exported. Standard settings are listed in the drop-down menu Setting under the entry [PREDEFINED] and can be customized, but they cannot be overwritten. After customizing any setting the name receives the suffix (edited). It is now a custom setting which is listed under the entry [EDITED] and thus can be exported. Edited settings can be saved under any name. Saved settings will be removed from [EDITED] and listed under [SAVED]. Saved and edited settings can be deleted manually.
Cleanup settings: All settings found under the entry [EDITED] will be deleted.
Compared to the ICC framework, which only supports perceptual rendering in applications, ColorLogic provides a choice of Perceptual Rendering options when creating profiles. In order to use a ColorLogic profile created with one of the special Perceptual Rendering options, the perceptual rendering intent must be set in the target application.
Note: All Perceptual Rendering options in the drop-down menu, including the Advanced Perceptual Rendering Options (such as Saturation, Chroma, Lightness, Gray Balance), are also applied to the Saturation Rendering Intent.
CoPrA offers the following methods in relation to perceptual rendering:
Standard Compression: ColorLogic’s standard method, which is well suited for most applications. Neutral tones are converted using a relative colorimetric approach. If the paper white of the used printing medium is significantly more yellow than the reference, the gray axis will look more yellow as well. The contrast range will be adapted for small color gamuts to preserve image definition.
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 a large to a small color space, the image definition is preserved in the highlights and shadows, unlike with a pure Relative Colorimetric conversion. Neutral tones are converted using the Relative Colorimetric intend. Out-of-gamut colors are cut off.
Absolute Compression: This method is based on the absolute colorimetric intent but with some differences. The contrast range in the highlights and shadows is adapted to avoid any loss of image definition. The rendering of neutral colors is based on absolute colorimetry without paper color simulation in the highlights. If the paper white of the used printing medium is significantly more yellow than the reference, the gray axis will look neutral despite the yellowish paper white.
Minimal Compression: This method is largely similar to the absolute colorimetric intent and only compensates close to the black and the white point. This results in maximum shadows and a preserved image definition while the paper white will not be simulated. Use this rendering intent to achieve a very close reproduction, for example when using print standards like ISO Coated V2 or GRACoL2006 Coated1v2 on a digital printer.
Note: As for the absolute colorimetric rendering intent, ensure that the target color space is larger or has at least a similar size to avoid any loss of image definition. For color conversions from larger to smaller color spaces use Absolute Compression to maintain the gray balance of the source color space.
Advanced Perceptual Rendering Options: The drop down menu allows changes to the overall Chroma, Lightness or Saturation of the profile using a slider. Chroma can be used to reduce or increase the chroma of highly saturated colors in the range between -20 and +20. Saturation can be used when highly saturated colors are required. As with the setting Chroma, the gray balance is not affected when moving the slider. Saturation can be used especially for large color spaces such as gamut extending Multicolor in order to achieve more brilliant colors.
Notes: ColorLogic intentionally keeps the chroma effect moderate. However, when increasing the chroma, ensure that the setting neither causes a loss of image definition in highly saturated colors, nor adversely affects colors such as skin tones.
The effect of each of these settings is shown in the gamut graph on the right. Increasing the saturation results in higher chroma and lower lightness, so more saturation will slightly darken the colors and they will appear more vibrant. In contrast, more chroma can result in high chroma colors being out-of-gamut and these colors would not be rendered by the given profile.
Gray Balance: Allows adjustment of the gray balance to create a cooler or warmer gray axis. cooler shifts the gray balance towards more bluish colors (negative b* values), warmer shifts it towards yellowish colors (positive b* values). The effect of the slider setting is visualized in the graphic.
Note: The setting Gray Balance works independently from the selected Perceptual Rendering method and allows visual adjustments based on personal color preferences.
When creating or updating printer profiles it may be necessary to optimize the measurement data. The Measurement Processing in CoPrA includes the optical Brightener Compensation, the Measurement Correction and the specification of a Viewing Condition.
Brightener Compensation: Recommended for bright white papers that contain optical brighteners. This correction weakens the effect of optical brighteners, which are evaluated differently by a measuring device compared to the human eye, and prevents negative accompanying effects such as a yellowish color reproduction.
Recommendation: Work with spectral measurement data whenever possible. When working with spectral measurement data, the function Brightener Compensation can achieve an optimum correction. The correction will only be executed,in contrast to colorimetric measurement data (Lab measurement data), if CoPrA recognizes the paper color as an optical brightener. However, it will not be carried out if CoPrA does not recognize the paper color as optical brightener, which, for example, is true for a blue-colored paper.
As a result of the viewing condition changes according to ISO 3664:2009, The updated standard makes it easier to spot the effects of optical brighteners (OBAs). So a minor correction is needed for devices using the M0 measuring method.
As a result of the viewing condition changes according to ISO 3664:2009, optical brighteners in papers are more strongly excited, a small correction is therefore also necessary for measuring instruments using the M0 measuring method.
Note: To specifically correct the effects of optical brighteners, use ColorAnt's Brightener tool before profile creation in CoPrA and disable the corresponding checkbox in CoPrA to avoid double compensation.
Measurement Correction: Identifies and resolves measurement errors without changing the printing behavior. Redundant measurement values, which occur in typical test charts such as ECI2002 or IT8.7/4, are taken into consideration for detecting consistent printing properties and will be intelligently included in the correction. Further corrections, like the removal of redundant measurement values or Smoothing, can be done in the separate measurement data processing program ColorAnt.
Recommendation: For your own measurement data select Measurement Correction as the default setting. However, this correction should be disabled for measurement values that have already been smoothed (such as FOGRA measurement values) or for measurement values that have already been processed with ColorAnt.
Viewing Condition: Typically, printer profiles are optimized for D50 viewing conditions, however, for different tasks, e.g. photos in a gallery under incandescent light (roughly corresponds to viewing condition A) or presentation displays under a trade fair lighting with suboptimal lighting conditions (e.g. fluorescent light), the lighting conditions can be taken into account when creating the profile.
To do so, select one of the three predefined viewing conditions or manually enter the measured viewing condition as Kelvin value or as XYZ value.
Alternatively, simply drag and drop a measurement file (TXT or CSV file) of the measured light onto the value field. CoPrA extracts the white point from the file and displays the value. CoPrA then uses this information to calculate a printer profile that makes your prints (with the selected viewing condition) appear in the same way as they would under the standard D50 viewing condition.
When using spectral measurement data of a test chart and a spectral light measurement of a viewing condition, CoPrA will use a spectral color model rather than the usual chromatic adaptation according to CIECAM02. Chromatic adaptation according to CIECAM02 will only be used if spectral light measurements are not provided as viewing condition and/or if the test chart does not contain spectral measurement values. To select a spectral light measurement to select the entry Emission in the drop-down menu Viewing Condition and then select your measurement data file in the subsequent dialog or just drag and drop your measurement data file onto the drop-down menu.
Note: CoPrA remembers the last used settings including the selected Viewing Condition. When creating new profiles, please check whether the selected viewing condition is in accordance with the purpose of the profile. If no specific viewing condition is required, always select the default D50.
In flexo printing, the first printed tone is often subject to a rather high tone value increase. Additionally, in some flexo printing processes there is no transfer of tone values below a certain percentage in the highlight areas. However, the simulation of those process properties is particularly important for proofing applications to truly simulate the final print result in the highlights. It may also be necessary to increase the tone values in the highlights when using the profile for production or separation.
For that reason, we integrated four different settings in CoPrA to adjust the Highlights.
Default: Results in 'normal' profiling behavior in highlight areas. Use this setting for all printing processes that don't require any adjustment of the first printed tone.
First Printed Tone (Preserve White): Defines when the first printed tone of the profile will be considered and appear in the proof (hard copy or soft proof). When the profile is used for separation, the paper white is maintained and small tonal values are immediately increased to the set tonal value resulting in a strong slope.
First Printed Tone (Minimal Tone): Defines when the first printed tone of the profile will be considered and appear in the proof (hard copy or soft proof). When the profile is used for separation, a tonal value corresponding to the set percentage is already printed in the white of all channels.
Printed Tone at 1 % (Proof): This setting defines the tone value to be achieved at 1% in proof direction of the profile. In separation direction of the profile, the setting Default is used (in contrast to other highlight settings).
Based on data: If the loaded measurement data contains enough data points in the highlights, CoPrA also provides information about the start of the first printed tone (see screenshot). This information may be used as a guide to assess the value that should be entered in the input field to the right.
Note: The information Based on data will only be displayed when one of the Highlight settings is selected from the drop-down menu and the data allows a different recognition of the first printed tone compared to the Default setting. Before using the value for profiling, we suggest analyzing the data in ColorAnt.
Multicolor Mode: Determines how colors will be built up in individual separations. Is only available when Multicolor measurement data has been loaded.
Note: A Multicolor license is required to use Multicolor features.
In CoPrA, the first three channels represent primary colors (usually CMY). They should form a sound color space (gamut) and should also be able to create a gray axis. The fourth channel should be black if a separation with UCR/GCR is desired. If black is absent in the Multicolor measurement data while automatic Black Calculation is selected, it will be recognized by CoPrA and the separation will not be generated. Black separation is disabled if the value for Max. Black in the Black Point and TAC setting is 0%. Additional spot color channels (e.g. Orange, Green or Violet in a CMYK-OGV 7 color data set) are regarded as color space expanding colors. The Multicolor Mode determines how color space expanding colors are factored in together with primary colors.
Strong: As much spot color as possible will be applied. Accordingly, less primaries will be used in the highly saturated color areas. This results in a greater use of color space expanding spot colors and therefore in highly saturated colors in the printout.
Smooth: Is the default setting and should remain unchanged if a particularly smooth and harmonious separation with saturated colors is required.
Note: The two Multicolor modes Smooth and Strong are similar but Smooth uses less color space expanding spot color channels.
Smooth – with special colors and Strong – with special colors: These two Multicolor modes are designed for applications in industrial printing, such as ceramic printing, in which the main colors are supplemented by additional light (e.g. Pink) or dark (e.g. Brown) color space expanding colors. They are an enhancement of the existing Multicolor modes Smooth and Strong, however, they also use additional colors that are not commonly used. For example, the additional color pink is used with a darker magenta in magenta gradations. Here, pink is used in light areas while magenta is used in dark areas.
1. The gray balance of the two Multicolor modes shows additional channels as bright or dark colors are incorporated into the gradations and gray balance curves.
2. These two Multicolor modes also support light inks in profiling, such as light and dark magenta. In principle, light and dark colors should be processed in the printer or RIP (Raster Image Processor). If they are not pre-processed from the RIP they require particularly large test charts for profiling.
3. It is also possible to combine light gray with black which in some printing processes like Flexo printing can mask noticeable artifacts in the highlights. However, appropriate test charts have to be used.
Generate separations with sparse inks: Is of interest for the packaging market as color separations are created in such a way that a certain hue uses as much as possible of a related spot color and very little or no primary colors. For example, in order to create a red hue as much as possible of a reddish spot color is used but very little to no magenta or yellow. A maximum of two or three colors are used for each color segment and, therefore, this Multicolor mode is practical to save process colors. However, black generation cannot be controlled and is based on the (separation) mode MaxK.
Note: In contrast to the Multicolor modes Smooth, Strong and Use CMYK only, the Multicolor mode Generate separations with sparse inks does not allow regulation of the Black Generation. Accordingly, these settings are grayed out.
Use CMYK only: Selecting this method results in a Multicolor printer profile that creates the desired number of channels (e.g. 7 channels) but is only composed of CMYK. The color space expanding spot color channels are not used for the separation but are used for the simulation of colors.
1. In package printing, there is sometimes a request for images and vectors composed of CMYK to be generated with only minimal changes to CMYK values and without spot colors – despite conversion into a Multicolor space. In this case, only spot colors, like Pantone colors, which are present as DeviceN in the PDF should be converted into the large Multicolor space. Such a workflow is possible in two easy steps: (1) Creation of a separation-preserving CMYK-to-Multicolor DeviceLink profile in CoPrA using the Multicolor method Use CMYK only. (2) Spot color conversion of the PDF using ColorLogic’s color server ZePrA.
2. In CoPrA all settings of Color Generation (i.e. the entire tab) depend on black being present in the measurement data. Therefore, black must be present in the measurement data or ICC profiles as fourth channel.
If black is not present in the measurement data as the fourth channel, this channel will be treated as if it were the black channel. As an example, if blue is present as the fourth channel, then all settings in the tab Color Generation will still treat the fourth – now blue – channel as a black channel. In this situation, spot colors can be used for the calculation of the gray balance and the black point, which may not be desirable.
Black Generation: Defines the method for the generation of black in the target color space and therefore influences the separation comprehensively.
The following modes are available in the drop-down menu:
Auto: Uses a medium GCR amount which is based on the measurement data.
UCR: Allows adjustment of the settings Black Start and Black Width.
GCR: Additionally allows the adjustment of the setting GCR Amount.
MinK: Uses only a minimal amount of black and generates a separation using the maximum amount of CMY.
MaxK: Uses a maximal amount of black and generates a separation using the minimum amount of CMY.
The methods UCR, GCR, MinK and MaxK generate a new separation, regardless of the separation of the target profile.
GCR Amount: Defines the amount of CMY that is replaced by black. At 0 only a low GCR amount is used which mainly impacts the shadows whereas at 100 a very strong GCR is used which effects the shadows and the highlights.
Black Start: Defines the starting point for the black generation. Black will be used if the minimum amount of CMY exceeds this limit.
Black Width: Defines the range in which black is generated outside the color-neutral area. The lower the value, the less black will be generated outside the color-neutral area.
100% Black: Prevents a pure black RGB text from being printed in four colors after conversion into a CMYK profile which would result in a blurred looking text. This is often the case with Office documents. Enabling 100% Black converts an RGB value of 0-0-0 to CMYK 0-0-0-100 (i.e. 100% black).
Pure Gray: Enabling this checkbox in a CMYK printer profile results in a gray balance which is composed of black ink only. However, this only makes sense if the printing system features a very neutral black from shadows to highlights.
Enabling Pure Gray in an RGB printer profile results in a gray balance which is composed of equal amounts of RGB values. This proves to be useful in RGB controlled (inkjet) print drivers.
Used Channels: Defines the channels to be used in a profile and offers a quick and easy way to select or exclude channels when separating data. The effect of selecting or excluding colors on Curves and the Gamut is immediately visualized in the graphic and the Black Point value.
By default all colors of the profile are enabled. To exclude a color click on the appropriate colored box. Multiple colors can be excluded. Excluded colors will be grayed out and marked with an X. To enable an excluded color simply click on it again.
Note: This function is particularly intelligent for Multicolor profiles, as it searches for replacement colors in the Multicolor channels when excluding a channel (e.g. Cyan), which can compensate for the missing channel in the gray balance. The alternatively calculated Multicolor channels are displayed grayed out in the panel Black Point and TAC (further information can be found in the toggle Black Point and TAC).
Example: If a brown chocolate artwork is intended to be printed in CMYK without using any Cyan in the separation, a CMYK printer profile can be created which only uses MYK. These types of profiles avoid unwanted Cyan dots in the separation and the converted artwork would appear visually close to a conversion with a complete CMYK profile. Obviously such a profile should not be used if the artwork contains Cyan based color combinations, such as cyan tones and blue or violet colors.
Avoid Dot-on-Dot: Prevents Black and Violet/Blue color combinations that could produce dot-on-dot effects in AM printing. Replaces some of the Black by CMY, therefore avoiding dot-on-dot effects.
Background: When using gamut extending process colors in traditional AM screening, such as CMYK+Orange+Green+Violet/Blue, the process colors Violet or Blue are often on the same screening angle as Black which can cause dot-on-dot issues leading to color and lightness variances. However, avoiding Black and Violet/Blue color combinations in separations would reduce the available gamut considerably and would also prevent dark bluish spot colors from being reproduced faithfully. By activating this feature the separation uses more of the CMY colors instead of Black thereby preventing dot-on-dot effects. For this function to work best, use a late Black Start and a rather weak GCR or even a UCR Black Generation setting.
Note: Other color combinations using the same AM screening angles such as Cyan and Orange or Magenta and Green are not affected by this feature as those combinations are rarely used in separations anyway.
Curves and Gamut: Visualize the effects of the selected color separation and Black Point settings. The Gamut view shows changes of the gamut shape immediately when altering settings and provides a real time preview of the loaded measurement data. In addition, the Gamut Volume is calculated and expressed in Lab units allowing to find the settings that produce the largest gamut (highest number) easily.
Example: The gamut view allows to observe how a low Black Width setting or a very late Black Start reduces the ability of a profile to render dark colors.
Black Point and TAC
Under Black Point and TAC the overall Total Area Coverage (TAC) and the TAC for the black point (Black TAC) can be defined. The black TAC represents the darkest color value of the profile which is usually identical with the maximum TAC.
The graphical display of each color contains a number field showing the amount of ink used in the profile. Depending on the selected Black Calculation the number fields are either enabled or disabled.
Note: The default window size sometimes truncates the input fields for Multicolor channels. Enlarge the window to display the input fields for all colors.
Black Calculation: Four different settings available for Printer Profiling (see screenshot below).
Auto: The calculation of the optimal black point (dark and neutral) is based on the measurement data. The values entered for Black TAC and Max.Black define limits which must not be exceeded, but may be lower if technically possible.
All channels are used to generate the black point (Black TAC), therefore individual channel editing is disabled. This mode will not use any Multicolor channels beside the first four channels (usually CMYK).
Note: If you do not have a default value for the Black TAC it is recommend to use 400% for the Black TAC as a starting point for the calculation.
Balance CMY: This setting adapts the CMY values to a pre-defined Max.Black value and generates a neutral black point. Define the Black TAC and TAC in accordance with the printing conditions. Max.Black should be set to the ideal value for the selected substrate. Similar to the setting Auto those values are regarded as maximum values which may be underrun if a neutral black point is not achievable.
Allows customization of the black channel (or in general the 4th channel) and the addition of Multicolor channels. Entered Multicolor color values are fixed – like the Max.Black value – and CMY values will be adjusted accordingly.
Note on excluding channels:
Basically Balance CMY allows editing of the black channel (or in general the fourth channel) and the Multicolor channels. The CMY channels are grayed out (see screenshot).
However, if a channel is excluded, the Multicolor channels are searched for a replacement color that can compensate for the missing channel in the gray balance. The replacement Multicolor channel is grayed out in the control panel Black Point and TAC (see screenshot).
Darkest: Calculates the darkest possible black point with maximum density/lowest L*. Allows generation of a black point without neutral a* and b* values and darker L* if available.
The values entered for Black TAC and Max.Black define limits which are not exceeded but may be lower if technically possible. Darkest uses the first 4 channels, usually CMYK. Possible multicolor channels are not considered, but can be used and changed manually if necessary (same as with the option Balance CMY).
Custom: Allows definition of the black point in the input boxes. The Black TAC value will then be recalculated. Allows editing of all channels.
- CoPrA calculates the Lab values based on the entered custom values. When changing custom values the resulting effects can be seen immediately. If you prefer CoPrA’s recommendations select the settings Balance CMY or Auto.
- For Multicolor profiles with more than four channels you can use the extra Multicolor channels for the black generation besides the first four channels (typically CMYK). However, the total area coverage (TAC) cannot exceed 400%. Values for the Multicolor channels can be entered manually when using the settings Balance CMY or Auto and these values will then be used to calculate the Black TAC. Usually it is not necessary to use those channels but sometimes a dark Multicolor channel adds desired contrast and definition. This can easily be checked by viewing the Lab values below the Custom fields. If the addition of a certain Multicolor channel decreases L* while a*b* values are not significantly altered, using this channel can be considered. However, the gray balance will use additional channels as well.
Note: With the settings Auto or Balance CMY CoPrA tries to use neutral a* and b* values for the Black Calculation. In contrast, selecting the setting Custom allows generation of a black point without neutral a* and b* values. Keep in mind that this can lead to a colored black point, which you can recognize by the a* and b* values.
TAC and Black TAC: The value for the maximum total area coverage can be entered in the input box TAC (value range: 0 to 400%). This value must not be exceeded. This also applies to multicolor profiles.
Note: The sliders limit each other, so the TAC can never be lower than the Black TAC (but it can be higher).
Max.Black: The maximum amount of black ink to be used (given by the separation) can be entered in the box Max.Black (range: 0 to 100%).
Black Point and TAC
The Total Area Coverage (TAC) and the TAC for the black point (Black TAC) can be defined by Black Point and TAC. The Black TAC represents the darkest color value of the profile which is usually identical to the maximum TAC.
Many modern printing systems allow a black point that is generated by using a low amount of ink. Sometimes the darkest color (Black TAC) can be printed using pure black which means that in extreme cases a black point of 100% K may be sufficient. Obviously, such a low TAC does not work for other color areas – it would not even be possible to print a true red, green or blue! Therefore we separated the Black TAC from the general TAC. This allows using the best setting for Black Calculation without restricting the color space.
The value for the black point (Black TAC), which results from your settings, will be displayed after a short calculation time below the text box Custom (outlined in red in the screenshot below).
The Lab value is particularly handy for assessing the effect on the black point when changing the TAC or Black TAC. The smaller the L* value, the deeper the black and the higher the contrast.
TAC and Black TAC can be adjusted separately in CoPrA
The total area coverage (TAC) – defined by the separation – and the Black TAC are identical in traditional printing systems. However, industrial printing applications and many digital printing systems show that the black point can be selected much lower than the total area coverage. To achieve a sound gray balance with a high contrast while maintaining highly saturated colors it is necessary to separate these two settings.
Advantages of a separate Black TAC
We would like to demonstrate how important it is to adjust the Black TAC independently from the total area coverage (TAC) using a digital printing system. Let’s assume the Black TAC and TAC could not be set separately and we had to use identical values for both of them. If you selected the setting Auto to calculate the black point and set a TAC of 300% (and therefore a Black TAC of 300% as well), CoPrA would calculate the best black point for this case. The result would be a total area coverage of 275% with a neutral black point (a* and b* are 0 respectively), but with a very light L* of 22.0 (outlined in red in the screenshot).
CoPrA allows the setting of the Black TAC separately from the total area coverage (TAC). As pure black is used in some digital printing systems as darkest printing color, the Black TAC can be reduced to 100% which results in a black point with a significantly darker (lower) L* value of 9.8. Using a separate setting for the Black TAC achieves a significantly higher and better contrast than a TAC which is linked to a Black TAC of 275%. Additionally, a total area coverage (TAC) of 300% ensures highly saturated colors. These precise settings are only possible with separate TAC values.
Format, Size and Further Processing
In the last step of the profile creation, assign a Name and choose the Format and Size of the profile (see screenshot).
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.
Create Profile Report (PDF): 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.
Calculate CMYK Profile: Only available when creating Multicolor printer profiles. Uses only the CMYK part of Multicolor data to create a CMYK profile. For example, this can be useful for Multicolor PDF files to enable the display of the CMYK part of a conversion in PDF viewers without Multicolor support.
Save Preview Profile: Is only available in Multicolor printer profiling. By activating this checkbox an ICC preview profile will be created in addition to the printer profile. It can be used as soft proof profile in Adobe Photoshop.
Notes: Preview profiles are only suitable for proofing purposes. Either a preview profile or a CMYK profile can be created in one profiling step, but not both.
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.
Introduction: Using Preview Profiles for Soft Proofs
Preview profiles allow soft proofing of image files in DeviceLink profiling and Multicolor printer profiling, without converting a file. Multicolor preview profiles provide a true color representation of images to be converted into the Multicolor color space in order to review the achievable result prior to the actual Multicolor conversion (More information can be found further down in the text). The same applies to DeviceLink conversions. Here, too, the DeviceLink preview profile can be used in Photoshop with the original data to visually review how the result of such a conversion would look like.
Preview profiles can be created together with DeviceLink or Multicolor printer profiles by activating the checkbox Save Preview Profile (see screenshots). Preview profiles have the suffix ‘preview‘ and are saved in the folder Profiles (macOS) or color (Windows), (macOS: /Users/Username/Library/ColorSync/Profiles, Windows: C:\Windows\System32\spool\drivers\color). Right clicking on the preview profile and selecting the menu entry Show file in the context menu will take you directly to the location of the selected profile.
A preview profile is a printer profile with the same color space as the source profile of the DeviceLink. It can be used as soft proof profile, for example in Adobe Photoshop. Preview profiles can be created for the following DeviceLink combinations:
RGB-to-CMYK, CMYK-to-CMYK, RGB-to-Multicolor and CMYK-to-Multicolor
Note: The creation of preview profiles is not available for DeviceLink profiles using more than four channels in the source color space since only preview profiles of the color spaces Gray, RGB or CMYK can be used in Photoshop. Multicolor printer profiles are not affected as their preview profiles are always RGB profiles which can be used in Photoshop.
Example: To adapt your RGB image data in RGB mode to the desired CMYK printing condition, use the preview profile of your RGB-to-CMYK DeviceLink as soft proof profile in Adobe Photoshop to check how the image would look like after the conversion. This allows specific RGB adjustments without the need to convert the RGB file early on. A preview profile is a very useful feature, particularly in view of storing RGB image data in media-neutral workflows.
Preview profiles can also be created for Multicolor printer profiles which allows a true color simulation of the color representation prior to application of the Multicolor profile. Although Adobe Photoshop CS4 or higher is able to convert image data using Multicolor profiles, the display of multichannel files is not a true color representation in Photoshop. So far, a true color representation of multichannel files is only possible using additional plug-ins and causes an increased workload. The preview profile function generates an RGB printer profile which features the same color visualization as the original Multicolor profile. Use this preview profile on an original image data for soft proofing.
Note: Preview profiles are only intended for soft proofs and should never be used for the actual conversion. A preview profile provides an excellent visual preview of the expected result of a DeviceLink conversion. However, the special features of the DeviceLink, such as preserving color purity, cannot be 100% emulated.
Using Preview Profiles for DeviceLinks in Adobe Photoshop
- Open the original image data to be converted using a DeviceLink profile in Adobe Photoshop.
- Either assign the Preview profile from CoPrA to this image file, or select the Preview profile in the dialog Customize Proof Condition as Device to Simulate (see screenshot).
Note: The color space of the preview profile is based on the color space of the DeviceLink’s source profile. It is an RGB preview profile for RGB-to-CMYK DeviceLinks and a CMYK preview profile for CMYK-to-CMYK DeviceLinks.
- Click Preserve CMYK Numbers to get a virtually exact preview of the expected color representation for the DeviceLink conversion.
Note: Pipette values do not correspond to the final DeviceLink conversion. Only the color representation in the soft proof does.
Using Multicolor Preview Profiles in Photoshop
- Open the original image data to be converted using a Multicolor printer profile in Adobe Photoshop (for example an RGB image).
- Select the Preview profile from CoPrA in the dialog Customize Proof Condition as Device to Simulate. Find the profile in the list of RGB profiles. The naming is based on the Multicolor profile name: Profile name_preview.icc
- Select the desired Rendering Intent and disable the checkbox Preserve RGB/CMYK Numbers.
Note: Eyedropper values do not correspond to the final DeviceLink conversion. This is only for a soft proof.
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.
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.
Multicolor Profiling and Chart Creation
Generating Multicolor Profiles in CoPrA
CoPrA supports three main chromatic primary colors which should span a suitably large gamut encompassing the gray balance. Typically this is CMY but it can be any other appropriate chromatic color combination.
Black can be added optionally as a 4th channel. If black is used it must be the fourth channel.
Up to two gamut extending colors can be used in between each section of the main primary colors.
Note: Following this approach, printer profiles of up to 10 channels can theoretically be created by CoPrA 5 and higher. However, it is not recommendable to use printer profiles with more than 8 channels in production as every additional channel increases the profile size exponentially so that either a very low grid size or an exorbitantly large profile had to be used.
Typical Multicolor Application
When using a typical Multicolor color space with CMYK parts, the additional inks Green, Orange and Violet extend the gamut in each section of the three primary colors. In between each section, a single gamut extending color is used creating a color space with 7 colors.
Advanced Multicolor Application
Some inkjet printers use Red and Orange in addition to the standard CMYK inks. CoPrA is able to profile such a 6 color printer since Orange and Red are two gamut extending colors of the main primary color sections Yellow and Magenta.
Note: When working with two gamut extending colors, special test charts must be used. CoPrA provides appropriate Multicolor test charts which are available via Tools > Open Testcharts folder > Multicolor.
Supported Color Systems
CoPrA allows to create DeviceLinks for all types of color spaces Gray, RGB, CMYK and Multicolor. Cross color space profiles are also supported, such as RGB to CMYK, CMYK to Grayscale or RGB/CMYK to Multicolor.
The following color systems are supported:
- 2- and 3-color systems
- 4-color systems with CMYK
- 4-color systems with CMY + either Red or Green or Blue, without Black
- 5-color systems: CMYK + either Red or Green or Blue
- 5 colour systems: CMY + either Red+Green, Red+Blue or Green+Blue, without black
- 6 colour systems: CMYK + either Red+Green, Red+Blue or Green+Blue
- 6 colour systems: CMY + Red+Green+Blue, without Black
- 7 colour systems: CMYK + Red+Green+Blue
- The CMY channels can even be exchanged for other similar colors, e.g. Magenta for another reddish color or Yellow for Beige and so on.
- Creation of DeviceLinks with up to 9 channels
Using Multicolor Test Charts
To create Multicolor profiles various test charts (multichannel Photoshop PSD files) with associated reference files are available for measuring with ColorAnt (or any suitable measuring software). These Multicolor test charts can be found in the folder Testcharts (in CoPrA's installation folder). The folder can be opened directly in CoPrA (menu Tools > Open test chart folder). The contained Multicolor test charts are specifically optimized for the algorithms used by CoPrA. Alternatively, you can create your own test charts for your multicolor process using ColorAnt/Custom Chart.
Selection of the correct test charts for your printing process is facilitated by the naming. Therefore, please note the following naming conventions:
- The name of the test chart contains the number of channels, the color combination and the number of color patches. From the name of the test chart CL-CMYKB-2140 reflects that it is a 5-channel test chart with the color combination CMYK+Blue and 2140 color patches.
- However, by 'Blue' we mean a fairly broad color range of reddish to greenish blue. For example, it contains violet as well.
- The following color abbreviations are used in folder and file names: R = Red, G = Green, B= Blue, V= Violet, O = Orange, Yg= Yellow-Green.
- For a Hexachrome printing process with CMYK+Orange+Green, use the corresponding test chart, CL-CMYKRG. Here, CMYKRG stands for CMYK+Red+Green, whereby red includes orange.
- For 7-color printing use the test chart CL-CMYKRGB. In addition to the colors CMYK it also contains the additional colors Red+Green+Blue.
- Nine special test charts for 6C and 7C color combinations have been available for two Gamut-extending colors (e.g. CMYK+Red+Orange). They can be found in the folder Special.
- The layout of the supplied test charts is designed to fit on A4 or US letter size and is optimized for the hand-held measuring devices supported by the Measure Tool. As all patches cannot go on one page the Multicolor charts are split in multiple pages which need to be measured in corresponding sequence (1_6 means it is the first of six pages).
- The total area coverage (TAC) of 400% is not exceeded in any of the test charts, not even in Multicolor test charts.
- Please make sure that the RIP or the output system of the printer supports Photoshop multichannel PSD files. If this is not the case please open the test charts in Photoshop (or another suitable image editing program) and save them as DCS2 files.
- The test charts are optimized for the X-Rite i1Pro measuring device, but can also be measured with other any single color measuring devices.
- For measurements with the X-Rite i1iO, Barbieri Spectro LFP and Konica-Minolta FD-9, we recommend creating a customized test chart file based on the corresponding reference file using ColorAnt’s Export Chart tool.
- To use a measuring device that is not supported by ColorAnt MeasureTool, it is necessary to create a test chart which is suitable for that measuring device and the intended printing process. Make sure to select the reference file matching the color system. The reference file is provided by CoPrA and located in the same folder as the test chart files. It can be recognized by the TXT extension and contains all required color patches. Please note that our reference files use a maximum total area coverage of up to 400%, even for 7 channel color systems.
- For Multicolor profiling - in contrast to CMYK Profiling - the test charts has to be adapted to the calculation algorithms in order to minimize color patches, otherwise, test charts would be exceptionally large.
Note: Multicolor profiling differs from manufacturer to manufacturer. If you would like to use measured Multicolor test charts from other manufacturers in CoPrA, please note that these test charts may not achieve optimal results in CoPrA.
- If it is not possible to reprint CoPrA's test charts and use existing measurement data from Multicolor test charts of other manufacturers, it is recommended to optimize these measurement data using ColorAnt before creating profiles in CoPrA. The Rescale tool allows adaption the measurement and reference values in ColorAnt according to suitable CoPrA test charts. Any missing measurement values will be interpolated which may result in inaccuracies if alternative test charts of other manufacturers reveal many gaps.
- CMY test charts are available for printing systems that do not use black. Please send an inquiry to email@example.com.
For example, when working with CMY+Blue, use the appropriate test chart from the folder CMY+B.
Note: Previously, many users worked with standard CMYK test charts, such as ECI2002 or IT8/7-4, for color combinations without black, replacing the K channel with blue, e.g. CMY+Blue. Although this approach seems practicable at first glance, it is not recommended, because the process color black plays an entirely different role to a gamut extending color blue in CMYK test charts. Accordingly, many color combinations in the CMYK test charts are unnecessary, or even missing for a blue process color. It is preferable to use CoPrA in combination with CMY+X test charts in order to obtain the best possible profile quality.