### 8.25. Compose

#### 8.25.1. Overview

Figure 16.172. Example for the “Compose” command

Decomposed image (RGB decomposition)

“Compose” applied

This command constructs an image from several grayscale images or layers, for instance from extracted RGB, HSV, etc. components. You can also build an image from grayscale images or layers created independently.

#### 8.25.2. Activating the Command

You can access this command from the main menu through Colors → Components → Compose…. It is enabled if your image is grayscale.

#### 8.25.3. Options

Figure 16.173. “Compose” command options

Compose Channels

  Here you can select the color space to be used: RGB, HSV, etc. The available options are described in the Decompose command.

Channel Representation

  Allows you to select which layer or image will be used for each channel. You may use this option, for example, to exchange color channels:

  Figure 16.174. Channel Representation example: exchange two channels

  Original image

  Decomposed to layers

  Composed image after using Channel Representation to switch red and green channels

  Mask Value: Instead of selecting a layer or an image to build the channel, you can give the channel a value from 0 to 255. But note that at least one channel must be formed from a layer or image.

| Tip
If you use different settings in Compose than when you used Decompose, for instance an image decomposed to RGB then re-composed to LAB, you will get interesting color effects. Test it!

8.24. Mono Mixer |  | 8.26. Decompose

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