ChannelChanger: Reseparating Image Channels according to the Output Colors

Requires a GMG OpenColor license and a direct connection to the application, please see Preferences

You can reseparate CMYK data using a GMG OpenColor ChannelChanger profile. This means you can change the input channels of an image area to any four channels available in your target color space.

In GMG OpenColor, you will need a project characterizing the output colors / target color space. You will then need to publish the separation profiles to make the project available to the GMG ColorPlugin. You may, but you do not need to, precalculate ChannelChanger profiles in GMG OpenColor. You also do not need to export the profiles. GMG ColorPlugin connects to GMG OpenColor and requests the needed profiles on-the-fly.

In the GMG ColorPlugin, you can then divide the image in sections that have a maximum of four output channels and then select the desired output channels.


The Output Channels list shows all output channels available in the selected GMG OpenColor project, regardless whether separation profiles have already been precalculated for the channels or not. In the example, Black has been replaced by Pantone 469 C.

How to use ChannelChanger

You will need a GMG OpenColor project with a published ChannelChanger separation profile.

Use the OpenColor Preview to get a color correct soft-proof.

  1. Open a CMYK image in Adobe Photoshop.
  2. Select an area or layer that you want to reseparate. The selection must not require more than four output channels.
  3. Click File > Automate > GMG ChannelChanger or select GMG ChannelChanger in the plugin panel.
  4. Select the GMG OpenColor project defining the target color space.
  5. Select maximal four output channels for your separation.
  6. In case of four output channels, define the key color of your separation.
  7. In case of four output channels, set the level of Gray Component Replacement (GCR). This way you can reduce the amount of CMY in gray areas while increasing the amount of Black.
  8. If you want to process hidden or locked layers, set the conversion options accordingly.
  9. Confirm your settings with the OK button.
    GMG ColorPlugin will request a ChannelChanger profile matching the selected output channels and settings from GMG OpenColor. If no matching profile exists, GMG OpenColor will calculate it and then send it to the plugin. As soon as the profile is available, the plugin will start the conversion. Requested profiles will also be shown in GMG OpenColor and might be reused later.