low pri features

docs/nodes/Mask Noisify.md

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+# Mask Noisify
+
+Add random noise to a binary mask by flipping pixels near boundaries. Equivalent to Gwyddion's mask_noisify.c.
+
+## Inputs
+
+| Name | Type | Required | Description |
+|------|------|----------|-------------|
+| mask | IMAGE | Yes | Binary mask to perturb |
+| field | DATA_FIELD | No | Optional field for preview background display |
+
+## Outputs
+
+| Name | Type | Description |
+|------|------|-------------|
+| mask | IMAGE | Noisified binary mask |
+
+## Controls
+
+| Name | Type | Default | Description |
+|------|------|---------|-------------|
+| density | FLOAT | 0.1 | Fraction of candidate pixels to flip (0.0--1.0) |
+| direction | dropdown | both | Which pixels to perturb: add (grow mask), remove (shrink mask), or both |
+| boundaries_only | BOOLEAN | True | Only modify pixels adjacent to a mask boundary |
+| seed | INT | 42 | Random seed for reproducible results (0--999999) |
+
+## Notes
+
+- Boundary detection uses four-neighbour comparison (up, down, left, right) via np.roll. A pixel is a boundary pixel if it differs from at least one of its four neighbours.
+- Direction modes control which candidates are eligible: "add" selects only unmasked boundary pixels, "remove" selects only masked boundary pixels, and "both" selects all boundary pixels.
+- Setting boundaries_only to False allows any pixel in the mask to be a candidate, not just those at edges.
+- The seed parameter ensures deterministic output for a given input, which is useful for repeatable experiments.