Masks
A mask is a binary or labeled volume that identifies specific regions within a volume image. Masks are the result of segmentation—the process of separating objects or structures from the background.
What is a Mask?
A mask has the same dimensions as the volume image it belongs to. Each voxel in a mask contains a label value:
- 0 = Background (not part of the region)
- 1 or higher = Part of a labeled region
Masks allow you to isolate, measure, and visualize specific structures independently from the rest of the data.
Binary Mask
A binary mask contains only two values:
| Value | Meaning |
|---|---|
| 0 | Background |
| 1 | Selected region |
Use binary masks when you need to identify a single structure or region, such as:
- A single organ
- One type of defect
- A specific material phase
Multi-label Mask
A multi-label mask can contain multiple distinct regions, each with a unique label value:
| Value | Example |
|---|---|
| 0 | Background |
| 1 | Region A (e.g., bone) |
| 2 | Region B (e.g., soft tissue) |
| 3 | Region C (e.g., air) |
| ... | Additional regions |
Multi-label masks are useful for:
- Segmenting multiple structures at once
- Anatomical labeling
- Material classification
- Porosity analysis with pore identification
Creating Masks
Volvicon provides several segmentation tools to create masks:
| Method | Description |
|---|---|
| Thresholding | Select voxels within an intensity range |
| Region growing | Expand from seed points based on similarity |
| Manual painting | Draw directly on slices |
| Morphological operations | Erode, dilate, open, close existing masks |
| Boolean operations | Combine masks using AND, OR, XOR, subtract |
Mask Properties
Each mask has these properties:
| Property | Description |
|---|---|
| Name | User-defined identifier |
| Color | Display color in 2D and 3D views |
| Opacity | Transparency level (0–100%) |
| Visibility | Show or hide the mask |
| Volume | Total volume of the masked region |
| Voxel count | Number of voxels in the mask |
Working with Masks
Once created, masks can be used to:
- Visualize regions with distinct colors in 2D and 3D
- Measure volume, surface area, and statistics
- Generate surface meshes for 3D printing or CAD
- Analyze porosity, defects, or structural features
- Export as image stacks or binary files
Related Topics
- Volume Grayscale Image – The source data for segmentation
- Surface Mesh – Converting masks to 3D surfaces