low pri features

docs/nodes/Grain Visualization.md

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+# Grain Visualization
+
+Visualize labeled grains as geometric shapes — inscribed discs, bounding boxes, centroid markers, or fitted ellipses. Produces a mask image with the chosen shapes and a labeled field where each grain has a unique integer value. Equivalent to Gwyddion's grain selection visualization (grain_makesel).
+
+## Inputs
+
+| Name | Type | Required | Description |
+|------|------|----------|-------------|
+| field | DATA_FIELD | Yes | Source data field providing spatial reference and calibration |
+| mask | IMAGE | Yes | Binary grain mask (white = grain region) |
+
+## Outputs
+
+| Name | Type | Description |
+|------|------|-------------|
+| result | IMAGE | Visualization mask with geometric shapes drawn for each grain |
+| labeled | DATA_FIELD | Labeled field where each connected grain region has a unique integer value |
+
+## Controls
+
+| Name | Type | Default | Description |
+|------|------|---------|-------------|
+| style | dropdown | inscribed_disc | Visualization style: inscribed_disc, bounding_box, centroid, or ellipse |
+| fill | BOOLEAN | False | When enabled, shapes are filled; when disabled, only outlines are drawn |
+
+## Notes
+
+- **inscribed_disc**: Draws a circle at each grain centroid with the inscribed disc radius (maximum of the distance transform within the grain).
+- **bounding_box**: Draws an axis-aligned rectangle around each grain's bounding box.
+- **centroid**: Draws small cross markers at each grain's centroid.
+- **ellipse**: Fits an ellipse to each grain using the inertia tensor to determine the major/minor axes and orientation angle.
+- When fill is disabled, outlines are drawn with approximately 1-2 pixel thickness.
+- The labeled output assigns each connected grain region a unique positive integer; background pixels are zero.
+- The mask and field must have the same pixel dimensions.