33 lines
1.5 KiB
Markdown
33 lines
1.5 KiB
Markdown
# Extend Pad
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Add configurable borders around a DATA_FIELD using various padding methods. Useful for preparing data for FFT-based operations that suffer from edge artifacts, or for aligning fields of different sizes. Equivalent to Gwyddion's `extend.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 field to pad |
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## Outputs
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| Name | Type | Description |
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|------|------|-------------|
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| padded | DATA_FIELD | Field with added borders |
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## Controls
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| Name | Type | Default | Description |
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|------|------|---------|-------------|
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| left | INT | 0 | Number of pixels to add on the left edge (0–1024) |
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| right | INT | 0 | Number of pixels to add on the right edge (0–1024) |
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| top | INT | 0 | Number of pixels to add on the top edge (0–1024) |
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| bottom | INT | 0 | Number of pixels to add on the bottom edge (0–1024) |
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| method | dropdown | mirror | Padding method: mean (fill with field mean), edge (replicate border pixels), mirror (reflect across edge), periodic (tile the field), or zero (fill with zeros) |
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## Notes
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- Mirror and periodic padding avoid sharp discontinuities at the border and are recommended before FFT-based filtering.
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- Edge padding replicates the outermost row/column of pixels into the border region.
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- Zero padding fills borders with 0.0 and can introduce step artifacts; consider mean padding as an alternative.
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- The output field's physical dimensions are extended proportionally to the added pixels.
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