34 lines
1.4 KiB
Markdown
34 lines
1.4 KiB
Markdown
# Grain Mark
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Mark grains by thresholding height, slope magnitude, or curvature. Thresholds are relative (0–1) to the data range. Small regions below min_size pixels are removed. Equivalent to Gwyddion's grain_mark.c module.
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## Inputs
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| Name | Type | Required | Description |
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|------|------|----------|-------------|
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| field | DATA_FIELD | Yes | Input surface |
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## Outputs
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| Name | Type | Description |
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|------|------|-------------|
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| mask | IMAGE | Binary mask of marked grains |
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## Controls
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| Name | Type | Default | Description |
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|------|------|---------|-------------|
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| criterion | dropdown | height | What to threshold: height, slope, or curvature |
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| threshold_low | FLOAT | 0.3 | Lower bound of the normalized threshold range (0–1) |
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| threshold_high | FLOAT | 1.0 | Upper bound of the normalized threshold range (0–1) |
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| min_size | INT | 10 | Minimum grain size in pixels; smaller regions are removed (1–100000) |
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| inverted | BOOLEAN | False | Invert the mask to mark valleys instead of peaks |
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## Notes
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- Thresholds are relative to the data range: 0.0 = minimum value, 1.0 = maximum value.
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- "slope" uses Sobel gradient magnitude — useful for marking edges and steep features.
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- "curvature" uses the Laplacian — useful for marking bumps or pits regardless of absolute height.
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- Use inverted=True to mark valleys, pores, or depressions instead of raised features.
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- For Otsu-based automatic thresholding, use the Threshold Mask node instead.
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