Separation Settings

Rendering Intent Description
Auto-Optimization Recommended and suitable for most requirements, this rendering intent automatically detects the differences between the color spaces and selects the best fitting calculation parameters, keeping colors as far as possible relative while using perceptual algorithms where necessary.
Best Color Accuracy – Relative Colorimetric Only available for CMYK-to-CMYK profiles, this rendering intent aims at achieving the highest color accuracy. In-gamut colors are reproduced in a color-accurate manner in the output color space. Higher saturated (out-of-gamut) colors are clipped. Optimal for color conversions where the input color space is almost identical to the output color space.
Best Visual Impression – Perceptual This rendering intent aims at preserving the visual impression of the original image, including saturation and detail, in the limited output color space, and is thus optimal for RGB-to-CMYK separations.
No Gamut Mapping – Absolute Colorimetric Creating a profile without gamut mapping has a similar meaning than using an absolute colorimetric rendering intent for ICC based color management. In-gamut colors are color-accurately reproduced and out-of-gamut colors are clipped. Without gamut mapping, it might not be possible to reproduce all source colors in the target color space.

It is highly recommended to use the option Keep Color Pure as it provides a good balance between preserving pure colors and preserving the color impression as intended by the designer or creator of the document. Each following option will be more strict on preserving pure colors, on the cost of higher deviations from the original document color space.

Option Description
Keep Color Pure Automatically purifies all colors that are only slightly contaminated by other colors.
Keep Pure (No DE Limit) Purifies all colors even if the resulting deviation from the characterization is high. 100% solid colors are kept pure, but the 100% value might not be preserved and might be separated to 98%, for example, unless you also select the option Keep Pure Solids (CMY).
Keep Pure Solids (CMY) This option forces 100% solid colors (C, M, Y, not K) and two color overprints, i. e. CM, CY, MY, to remain at 100%. A solid color overprinting with Black is excluded unless you also select the option Keep Pure Solids (Overprints with Black).
Keep Pure Solids (Overprints with Black) This option is only available if you have selected Keep Pure Solids (CMY). 100% solid colors (C, M, Y) overprinting with black are kept at 100%.
Pure Black Keeps the black axis pure. 100% Black is kept at 100% Black and will not be supplemented with or replaced by CMY.
Option Description
Total Area Coverage Short: TAC. Adjusts the maximum amount of CMYK in percent.
Separation Mode
  • New Separation: Reseparates the black channel to achieve a consistent Black separation over the complete color space.
  • Keep Black Separation: Preserves the black channel and the key axis across the entire color space, that is, color values without K will remain without K.
Black Start

Percentage at which Black ink is starting to be used.

Black Width Defines how much black ink is used in saturated colors. We recommend a value between 80-100%.

UCR
Light
Midtone
Shadow

Under color removal (UCR) is a technique to reduce the amount of CMY in neutral areas while increasing the amount of Black. Thus, the image areas with reduced CMY can dry faster between each printing unit on a printing press. For profiling, you can determine the Black amount in the highlights, the midtones and the shadows.
Option Description
Total Area Coverage Short: TAC. Adjusts the maximum amount of CMYK in percent.
Ink Saving If you select one of the ink saving presets Light, Medium, or Strong, GMG OpenColor will adjust relevant parameters like the GCR level automatically for you to save ink. If you do not want to use predefined settings, you can select the option Custom and adjust all relevant settings individually by hand.
GCR Level (CMYK) The Separation Rules define how much Black will be used. GCR Level (CMYK) lets you increase the GCR level. It will affect only CMYK inks, not any additional inks that might be part of the ink configuration. Gray component replacement (GCR) is a technique to reduce the amount of CMY in gray areas while increasing the amount of Black. Thus, less ink can be used and the resulting output is less sensitive to changes in the printing variables. If the GCR level is set to 0, the total Black ink will be the sum of the Black ink usage for single colors as defined in the Separation Rules.
Black Start (CMYK) The Separation Rules define the black start, i.e. the percentage at which Black ink is starting to be used. Black Start (CMYK) lets you use a higher black start. It will affect only CMYK inks, not any additional inks that might be part of the ink configuration.
Allow Additional Inks in Overprints

This option defines how strict the ink splitting defined for single colors in the Separation Rules will be applied to overprinting colors. If this option is selected, the Separation Rules are still regarded for overprints, but GMG OpenColor might also use additional inks if it makes sense to do so. Allow Additional Inks in Overprints is especially useful in cases where the resulting color will be substantially different than the individual colors, for example, when blue is overprinted with yellow. You might not want to use the output ink Green in blue areas and also not in yellow areas. But when blue is overprinted with yellow, resulting in a green color, it makes sense to use Green.

Example: The Separation Rules define that the output ink Green must not be used to print a specific blue spot color. If Allow Additional Inks in Overprints is selected, Green will be used in overprints with the blue spot color, for example, in overprints with a yellow color.

To ensure smooth gradations, the amount of Green will be limited automatically by GMG OpenColor. The amount of ink depends on the limits for the single colors. If the single color does not use the ink at all, the overprinted color will not use a high amount. You can increase the amount by defining a higher ink usage for the single color, as explained in the following example.

The screenshot shows three ink variants of Pantone 228 C.

The first ink variant uses only CMK. The second one uses 5% of Violet, and the third one 10%.

If Allow Additional Inks in Overprints is deselected, the first ink variant will not use Violet at all. The second ink variant will use exactly 5% of Violet, regardless whether it is used as a single color or in an overprint.

If Allow Additional Inks in Overprints is selected, the first ink variant will use Violet only in overprints, but a lesser amount than ink variant 2. Ink variant 2 will use 5% of Violet in single color prints, but a higher amount of Violet in overprints. Ink variant 3 will use the highest amount of Violet in overprints.

Gamut Mapping

GMG OpenColor applies Gamut Mapping settings in a smart way: If the difference between source and target color space (target printing condition), i.e. paper tint, black point, size and form of the color space, is small, Gamut Mapping will not be applied regardless of the set level.

Option Description
Gray Adjustment to Target Media

The Gray Adjustment to Target Media is important in cases where the target printing condition uses a substrate with a different white point than the output intent of the document. Gray Adjustment to Target Media defines how much the paper tint of the target print medium will affect the printed colors. It mainly affects the gray balance and less saturated colors.

  • Move the slider to the left to preserve the original colors, thus "ignoring" the new paper tint.
  • If you move the slider to the right, the new paper tint will have more effect on the colors, especially on the highlights and on the gray balance.

If the Gray Adjustment to Target Media is set to 0, the separation profile will preserve the original gray axis as best as possible. The design will keep the original color impression of the input document. GMG OpenColor takes care of the smoothness and avoid visible breaks between the paper tint and very light areas. A low value is the right choice if the final design needs to be as close to the original design as possible, for example, to ensure consistency whenever print products of the same campaign are printed under different printing conditions. In most cases, 30 is the ideal value to ensure a harmonic visual appearance. Please note that especially in the highlights, a prominent paper tint in the target color space such as Yellowish cannot be fully compensated. For example, a pure white color will be out of gamut.

If the Gray Adjustment to Target Media is set to 100, the gray axis will be perceptually mapped to the output color space. The design will be adapted to the target paper tint. For more or less gray designs and motives, a high value can be useful to avoid colors suddenly appearing in a gray area, for example, in a screws catalog.

Example: In a separation from ISO Coated v2 (39L) to PSO Uncoated v3 (52), the white point of PSO Uncoated v3 (52) is much more blueish. If the Gray Adjustment to Target Media is set to 0, the design will keep the more yellowish appearance. If it is set to 100, the design will be adapted to the more blueish gray balance.

Roman 16 test image separated from ISO Coated v2 (39L) to PSO Uncoated v3 (52), demonstrating both extreme Gray Adjustment to Target Media settings.
Black Point Compensation
  • You can increase the Black Point Compensation (BPC) level by moving the slider to the right. It preserves image detail in the shadows by minimizing clipping in the shadows. Thus, the full dynamic range of the output color space in the shadows can be used. In most cases, BPC will also lead to a general decrease in saturation. If the black point of the target color space is darker than the black point of the source, BPC might increase the saturation.
  • If no Black Point Compensation is used by moving the slider to the left side, changes to in-gamut colors in the shadows are minimized, though detail might be lost. Saturation is higher. Deactivate Black Point Compensation if you need a color as deep black as possible or to avoid color shifts. For most Packaging applications, it is recommended to decrease BPC or set it to 0 to avoid any change of saturated or dark colors (with the risk of clipping).

We recommend to use a high value for CMYK-to-CMYK separations of image data. Use a low value for packaging printed on coated media.
Gamut Expansion Use Gamut Expansion to exploit the full available color space of your printer. Gamut Expansion is useful for all printers with a large color space, with CMYK only or with additional inks. Colors will be boosted to the edge of the available printer color space. Colors might be drastically changed, while the gray balance remains unchanged. Color boosting is technically possible only if the target color space is significantly larger than the source. If your printer uses additional inks, also select the option Allow Additional Inks in Overprints (see "Allow Additional Inks in Overprints ") for a maximum effect.
Option Description
Select Inks Select maximal four output inks for your separation.
Key Color

In case of four output colors you can define the key color of your separation.
GCR Level Grey component replacement (GCR) is a technique to reduce the amount of CMY in grey areas while increasing the amount of Black. Thus, less ink can be used and the resulting output is less susceptible to changes in the printing variables. The GCR level determines the amount of GCR regarding your separation.
Option Description
Calculate Single Profile Calculates a single profile with all output inks instead of multiple profile variants with all combinations of output inks.
Extended Ink Start

Ink start for the additional inks used to extend the color space.