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DisplayMask

What is it?

The DisplayMask node creates a mask from an input image by extracting a specific channel (red, green, blue, or alpha). A mask is a grayscale image where white areas represent fully opaque regions and black areas represent fully transparent regions. This node is useful for visualizing and working with different color channels in images.

When would I use it?

Use this node when you want to:

  • Extract transparency information from an image as a visible mask
  • Extract specific color channels (red, green, blue) as masks
  • Create masks for image editing workflows
  • Visualize different channels of an image
  • Generate masks for use in other image processing nodes
  • Debug transparency or color channel issues in your image pipeline

How to use it

Basic Setup

  1. Add the DisplayMask node to your workflow
  2. Connect an image source to the "input_image" input
  3. Select the desired channel from the "channel" dropdown
  4. The generated mask will be available at the "output_mask" parameter

Parameters

  • input_image: The image to create a mask from (can be connected from other image nodes)
  • channel: The channel to extract as a mask (red, green, blue, or alpha)

Outputs

  • output_mask: A grayscale mask image created from the selected channel of the input image

Example

A common workflow pattern:

  1. Generate or load an image using nodes like GenerateImage or LoadImage
  2. Connect that image to the DisplayMask node's "input_image" parameter
  3. Select the desired channel (e.g., "alpha" for transparency, "red" for red channel)
  4. The DisplayMask node will extract the selected channel and create a visible mask
  5. Connect the "output_mask" to DisplayImage to view the mask, or to other mask processing nodes

Channel Options

  • alpha: Extracts the transparency channel (default) - useful for seeing which parts of an image are transparent
  • red: Extracts the red color channel - useful for isolating red elements in an image
  • green: Extracts the green color channel - useful for isolating green elements in an image
  • blue: Extracts the blue color channel - useful for isolating blue elements in an image

Important Notes

  • Channel Extraction: The node extracts the specified channel from the input image to create the mask
  • Grayscale Output: The resulting mask is a grayscale image where white represents high values and black represents low values for the selected channel
  • Real-time Processing: The node processes the image immediately when a connection is made or when the input value or channel selection changes
  • Output Format: The mask is saved as a PNG file to preserve quality
  • Image Mode Support: Supports RGB, RGBA, grayscale (L), and grayscale+alpha (LA) image modes

Common Issues

  • No Output: Check that your image source is properly connected to the "input_image" parameter
  • Solid Black Mask: This may indicate that the selected channel has no variation or low values
  • Solid White Mask: This may indicate that the selected channel has high values throughout
  • Unsupported Mode Error: The image format may not support the selected channel (e.g., alpha channel in RGB images)

Technical Details

The node uses channel extraction logic to:

  • Load the input image from its URL
  • Extract the specified channel (red, green, blue, or alpha)
  • Convert it to a grayscale mask
  • Save the result as a new image artifact

For RGB images, alpha channel selection will fallback to the red channel since RGB doesn't have an alpha channel.