Mask Visualization¶
Class: MaskVisualizationBlockV1
Source: inference.core.workflows.core_steps.visualizations.mask.v1.MaskVisualizationBlockV1
Fill segmentation masks with semi-transparent color overlays, creating solid color fills that precisely follow the shape of detected objects from instance segmentation predictions.
How This Block Works¶
This block takes an image and instance segmentation predictions (with masks) and fills the mask regions with colored overlays. The block:
- Takes an image and instance segmentation predictions (with masks) as input
- Extracts segmentation masks for each detected object from the predictions
- Applies color styling to each mask based on the selected color palette, with colors assigned by class, index, or track ID
- Fills the mask regions with solid colors using Supervision's MaskAnnotator
- Blends the colored mask overlays with the original image using the specified opacity level
- Returns an annotated image where mask regions are filled with semi-transparent colors, while non-masked areas remain unchanged
The block fills the exact shape of each object's segmentation mask with colored overlays, creating solid color fills that precisely follow object boundaries. Unlike polygon visualization (which draws outlines) or bounding box visualizations (which use rectangular regions), mask visualization fills the entire mask area with color, providing clear visual indication of the segmented regions. The opacity parameter controls how transparent the mask overlay is, allowing you to see the original image details through the colored mask (lower opacity) or create more opaque fills (higher opacity) that better obscure background details. This block requires instance segmentation predictions with mask data, as it specifically works with segmentation masks to create precise, shape-following color fills.
Common Use Cases¶
- Instance Segmentation Visualization: Visualize instance segmentation results by filling mask regions with colors to clearly show segmented objects, validate segmentation quality, or highlight detected regions in analysis workflows
- Precise Shape-Following Overlays: Fill objects with colors that exactly match their segmented shapes, useful for applications requiring accurate region visualization such as medical imaging, quality control, or precise object identification
- Mask-Based Object Highlighting: Highlight segmented objects with colored overlays that follow exact object boundaries, providing clear visual distinction between different objects or object classes
- Segmentation Model Validation: Visualize segmentation predictions with colored mask fills to verify model performance, identify segmentation errors, or validate mask accuracy in model development and debugging workflows
- Medical and Scientific Imaging: Display segmented regions in medical imaging, microscopy, or scientific analysis applications where colored mask overlays help visualize tissue boundaries, cell regions, or measured areas
- Mask Quality Inspection: Use colored mask fills to inspect segmentation quality, verify mask boundaries, or identify areas where segmentation may need improvement in training data or model outputs
Connecting to Other Blocks¶
The annotated image from this block can be connected to:
- Other visualization blocks (e.g., Label Visualization, Polygon Visualization, Bounding Box Visualization) to combine mask fills with additional annotations (labels, outlines) for comprehensive visualization
- Data storage blocks (e.g., Local File Sink, CSV Formatter, Roboflow Dataset Upload) to save images with mask overlays for documentation, reporting, or analysis
- Webhook blocks to send visualized results with mask fills to external systems, APIs, or web applications for display in dashboards or monitoring tools
- Notification blocks (e.g., Email Notification, Slack Notification) to send annotated images with mask overlays as visual evidence in alerts or reports
- Video output blocks to create annotated video streams or recordings with mask fills for live monitoring, segmentation visualization, or post-processing analysis
Type identifier¶
Use the following identifier in step "type" field: roboflow_core/mask_visualization@v1to add the block as
as step in your workflow.
Properties¶
| Name | Type | Description | Refs |
|---|---|---|---|
name |
str |
Enter a unique identifier for this step.. | ❌ |
copy_image |
bool |
Enable this option to create a copy of the input image for visualization, preserving the original. Use this when stacking multiple visualizations.. | ✅ |
color_palette |
str |
Select a color palette for the visualised elements.. | ✅ |
palette_size |
int |
Specify the number of colors in the palette. This applies when using custom or Matplotlib palettes.. | ✅ |
custom_colors |
List[str] |
Define a list of custom colors for bounding boxes in HEX format.. | ✅ |
color_axis |
str |
Choose how bounding box colors are assigned.. | ✅ |
opacity |
float |
Opacity of the mask overlay, ranging from 0.0 (fully transparent) to 1.0 (fully opaque). Controls the transparency of the colored mask fill. Lower values (e.g., 0.3-0.5) create semi-transparent overlays that allow original image details to show through, while higher values (e.g., 0.7-1.0) create more opaque fills that better obscure background details. Typical values range from 0.4 to 0.7 for balanced visualization where both the mask and underlying image are visible.. | ✅ |
The Refs column marks possibility to parametrise the property with dynamic values available
in workflow runtime. See Bindings for more info.
Available Connections¶
Compatible Blocks
Check what blocks you can connect to Mask Visualization in version v1.
- inputs:
Local File Sink,Background Color Visualization,Roboflow Dataset Upload,Polygon Zone Visualization,Line Counter Visualization,Path Deviation,Image Preprocessing,SAM 3,Instance Segmentation Model,SIFT Comparison,Segment Anything 2 Model,Absolute Static Crop,Qwen3.5-VL,LMM,Camera Focus,Keypoint Detection Model,Clip Comparison,Stability AI Outpainting,Heatmap Visualization,Anthropic Claude,EasyOCR,Mask Visualization,Text Display,VLM As Detector,Detection Event Log,Image Slicer,Stitch Images,Roboflow Custom Metadata,Email Notification,OpenAI,Blur Visualization,Velocity,SAM 3,Detections Combine,GLM-OCR,Time in Zone,Background Subtraction,QR Code Generator,Mask Area Measurement,Multi-Label Classification Model,Object Detection Model,Webhook Sink,SAM 3,Twilio SMS Notification,CogVLM,S3 Sink,Detection Offset,Line Counter,Bounding Rectangle,SIFT,VLM As Classifier,Polygon Visualization,Trace Visualization,Pixel Color Count,Camera Focus,Pixelate Visualization,LMM For Classification,Reference Path Visualization,Line Counter,Contrast Equalization,Classification Label Visualization,Dynamic Crop,Halo Visualization,Anthropic Claude,Perspective Correction,JSON Parser,Grid Visualization,Email Notification,Depth Estimation,VLM As Classifier,Image Slicer,Model Comparison Visualization,Instance Segmentation Model,Image Blur,Seg Preview,OpenAI,Path Deviation,Google Vision OCR,OCR Model,Bounding Box Visualization,Ellipse Visualization,Size Measurement,Triangle Visualization,Florence-2 Model,Llama 3.2 Vision,Detections Stitch,Label Visualization,Time in Zone,Florence-2 Model,Image Contours,Time in Zone,PTZ Tracking (ONVIF),Icon Visualization,Stability AI Image Generation,Anthropic Claude,Image Convert Grayscale,Google Gemini,Distance Measurement,Google Gemini,Crop Visualization,Corner Visualization,OpenAI,Stitch OCR Detections,Stitch OCR Detections,Semantic Segmentation Model,Detections Stabilizer,CSV Formatter,Polygon Visualization,Detections Transformation,Model Monitoring Inference Aggregator,Single-Label Classification Model,Circle Visualization,Relative Static Crop,Slack Notification,Camera Calibration,OpenAI,Identify Changes,Detections Filter,Stability AI Inpainting,Keypoint Visualization,Twilio SMS/MMS Notification,Dot Visualization,Identify Outliers,Color Visualization,Dynamic Zone,Dimension Collapse,Buffer,Image Threshold,Detections Classes Replacement,Detections List Roll-Up,Template Matching,Morphological Transformation,SIFT Comparison,Detections Consensus,Google Gemini,Clip Comparison,VLM As Detector,Halo Visualization,Roboflow Dataset Upload,Motion Detection - outputs:
Background Color Visualization,OCR Model,Bounding Box Visualization,Roboflow Dataset Upload,Gaze Detection,Polygon Zone Visualization,Line Counter Visualization,Ellipse Visualization,Image Preprocessing,Triangle Visualization,Keypoint Detection Model,SAM 3,Instance Segmentation Model,Florence-2 Model,SIFT Comparison,Qwen3.5-VL,Segment Anything 2 Model,Absolute Static Crop,Llama 3.2 Vision,Detections Stitch,LMM,Camera Focus,Keypoint Detection Model,Clip Comparison,YOLO-World Model,Stability AI Outpainting,Anthropic Claude,EasyOCR,Heatmap Visualization,Mask Visualization,Text Display,VLM As Detector,SORT Tracker,Image Slicer,Label Visualization,Stitch Images,Barcode Detection,OC-SORT Tracker,Florence-2 Model,Image Contours,Time in Zone,OpenAI,Blur Visualization,SmolVLM2,Icon Visualization,Multi-Label Classification Model,Stability AI Image Generation,SAM 3,GLM-OCR,Anthropic Claude,Image Convert Grayscale,Perception Encoder Embedding Model,Google Gemini,Background Subtraction,Google Gemini,Multi-Label Classification Model,Moondream2,Crop Visualization,Qwen2.5-VL,Object Detection Model,Corner Visualization,OpenAI,SAM 3,Semantic Segmentation Model,Dominant Color,CogVLM,Detections Stabilizer,Polygon Visualization,Qwen3-VL,SIFT,VLM As Classifier,Single-Label Classification Model,Circle Visualization,Byte Tracker,Polygon Visualization,Relative Static Crop,Trace Visualization,Pixel Color Count,Camera Focus,Pixelate Visualization,Camera Calibration,OpenAI,LMM For Classification,Object Detection Model,Reference Path Visualization,Stability AI Inpainting,Keypoint Visualization,Contrast Equalization,Twilio SMS/MMS Notification,Classification Label Visualization,Dot Visualization,CLIP Embedding Model,Color Visualization,Dynamic Crop,Halo Visualization,Buffer,Anthropic Claude,Image Threshold,Perspective Correction,QR Code Detection,Template Matching,Morphological Transformation,Email Notification,Depth Estimation,VLM As Classifier,Single-Label Classification Model,Image Slicer,Model Comparison Visualization,Instance Segmentation Model,Image Blur,Google Gemini,Clip Comparison,VLM As Detector,Seg Preview,OpenAI,Halo Visualization,ByteTrack Tracker,Roboflow Dataset Upload,Motion Detection,Google Vision OCR
Input and Output Bindings¶
The available connections depend on its binding kinds. Check what binding kinds
Mask Visualization in version v1 has.
Bindings
-
input
image(image): The image to visualize on..copy_image(boolean): Enable this option to create a copy of the input image for visualization, preserving the original. Use this when stacking multiple visualizations..predictions(Union[instance_segmentation_prediction,rle_instance_segmentation_prediction,semantic_segmentation_prediction]): Segmentation predictions containing masks for detected objects. The block uses segmentation masks to create colored fills that precisely follow object or class boundaries. Requires segmentation model outputs with mask data, which may be RLE-encoded..color_palette(string): Select a color palette for the visualised elements..palette_size(integer): Specify the number of colors in the palette. This applies when using custom or Matplotlib palettes..custom_colors(list_of_values): Define a list of custom colors for bounding boxes in HEX format..color_axis(string): Choose how bounding box colors are assigned..opacity(float_zero_to_one): Opacity of the mask overlay, ranging from 0.0 (fully transparent) to 1.0 (fully opaque). Controls the transparency of the colored mask fill. Lower values (e.g., 0.3-0.5) create semi-transparent overlays that allow original image details to show through, while higher values (e.g., 0.7-1.0) create more opaque fills that better obscure background details. Typical values range from 0.4 to 0.7 for balanced visualization where both the mask and underlying image are visible..
-
output
image(image): Image in workflows.
Example JSON definition of step Mask Visualization in version v1
{
"name": "<your_step_name_here>",
"type": "roboflow_core/mask_visualization@v1",
"image": "$inputs.image",
"copy_image": true,
"predictions": "$steps.instance_segmentation_model.predictions",
"color_palette": "DEFAULT",
"palette_size": 10,
"custom_colors": [
"#FF0000",
"#00FF00",
"#0000FF"
],
"color_axis": "CLASS",
"opacity": 0.5
}