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docs/nodes/Outlier Mask.md

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+# Outlier Mask
+
+Create a mask marking pixels that deviate more than N standard deviations from the mean. Quick way to identify noise spikes and defects. Equivalent to Gwyddion's outliers.c module.
+
+## Inputs
+
+| Name | Type | Required | Description |
+|------|------|----------|-------------|
+| field | DATA_FIELD | Yes | Input surface |
+
+## Outputs
+
+| Name | Type | Description |
+|------|------|-------------|
+| mask | IMAGE | Binary mask of outlier pixels |
+
+## Controls
+
+| Name | Type | Default | Description |
+|------|------|---------|-------------|
+| sigma_threshold | FLOAT | 3.0 | Number of standard deviations beyond which a pixel is an outlier (1.0–10.0) |
+| mode | dropdown | both | Which outliers to flag: both (high and low), high only, or low only |
+
+## Notes
+
+- A pixel is flagged if its z-score (data - mean) / std exceeds the threshold.
+- 3σ catches ~0.3% of pixels in a Gaussian distribution. Use 2σ for aggressive filtering or 5σ for conservative.
+- The resulting mask can be fed to Laplace Interpolation or Fractal Interpolation to fill the defects.
+- For a uniform (constant) field, no pixels are flagged regardless of threshold.