Expanded Color Gamut (ECG)

Expanded Color Gamut (ECG) printing, also referred to as Fixed Color Palette printing, uses a standardized ink set enhancing the color space to reproduce any color used in the design. In the plugin, up to three additional inks can be used. The inks need to be between the CMYK process colors, i. e. Red or Orange, Green, and/or Blue or Violet.

This method allows for a virtually unlimited number of colors in the design and also for nesting print jobs with different color channels, without changing the ink configuration of the printing machine.

Using ECG, design can be more eye-catching, resulting in highly saturated colors. The print result is closer to the original RGB design. As the ink setup is standardized, printers are saving on make-ready and ink costs.

As the profile calculation takes a considerable amount of time, GMG OpenColor calculates the required separation profiles in advance and provides them to the plugin on request via a direct connection.

Separate RGB images to your custom ECG ink setup with up to 7 output channels.
You can use Red or Orange, Green, and Blue or Violet inks.
To avoid Moiré effects, the inks that are used in addition to CMYK will be used only in the respective area of the color space. For example, Orange is used only in the RMYK area. This means there will be no overprinting between complementary colors such as Cyan and Red or Orange.
To preserve the gray balance, the inks that are used in addition to CMYK are not used in image areas with a low saturation.

Prerequisites

To create a ChannelExtender separation profile, the GMG OpenColor project needs to meet the following requirements. Otherwise, the RGB to ChannelExtender action will not be available. Please check the Ink Settings accordingly.

Input color space: Needs to be an RGB ICC profile matching the color space of the document you want to edit in Adobe Photoshop.
Output inks: CMYK + 1 to 3 additional inks. CMYK inks must have the appropriate Usage parameter (Separation Cyan, Separation Magenta, Separation Yellow, Contrast Black). Additional output inks need to be defined as Separation (other) or Contrast (other).
Color of additional output inks (referring to the LCH color model):
- Hue (H): Consider which CMYK process colors are neighboring the additional output ink in the color wheel. The hue angle of the additional output ink needs to be in-between the hue angles of these two colors (regarding the minor sector of the wheel). The hue must also keep a minimum distance of 10° to the hue of these two colors.
  Example: If the additional ink is Orange, the next neighbors are Magenta and Yellow. Let us assume we have the following output inks defined as LCH: Magenta 49 L, 75 C, 360° H; Yellow 89 L, 93 C, 93° H; PANTONE Orange 021 C 61 L, 108 C, 52° H.
  We then check the hue angles: Magenta has 360° and Yellow 93°. PANTONE Orange 021 C has a hue of 52°, which is between 360° and 93°. Concerning the minimum hue distance, the hue of Orange must be between 10° (distance from 360°) and 83°. As this is also true, PANTONE Orange 021 C fulfills the hue requirements for an additional output ink in this ink setup.
- Chroma (C): The chroma of an additional output ink must be at least 75% of the chroma of the neighboring process color with the higher chroma value.
  Example: Let us consider the same inks we used in the example above. If Magenta has a chroma of 75 and Yellow of 93, the additional output ink Orange needs to have a saturation equal to 70 or higher (75% of the higher value, i.e. 93.) The chroma of PANTONE Orange 021 C is actually higher than that of the process colors so this requirement is met.
Screen angle: Complementary colors must use the same angle. For example, Red and Cyan must use the same screen angle.