36 lines
2.0 KiB
Markdown
36 lines
2.0 KiB
Markdown
# Perspective Correction
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Fix perspective distortion in a DATA_FIELD via a projective (homography) transform. Each corner can be shifted by a fractional offset to map a distorted quadrilateral back to a rectangle. Equivalent to Gwyddion's `correct_perspective.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 with perspective distortion |
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## Outputs
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| Name | Type | Description |
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|------|------|-------------|
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| corrected | DATA_FIELD | Perspective-corrected field |
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## Controls
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| Name | Type | Default | Description |
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|------|------|---------|-------------|
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| top_left_x | FLOAT | 0.0 | Horizontal offset of the top-left corner as a fraction of image width (-0.5-0.5) |
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| top_left_y | FLOAT | 0.0 | Vertical offset of the top-left corner as a fraction of image height (-0.5-0.5) |
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| top_right_x | FLOAT | 0.0 | Horizontal offset of the top-right corner as a fraction of image width (-0.5-0.5) |
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| top_right_y | FLOAT | 0.0 | Vertical offset of the top-right corner as a fraction of image height (-0.5-0.5) |
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| bottom_left_x | FLOAT | 0.0 | Horizontal offset of the bottom-left corner as a fraction of image width (-0.5-0.5) |
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| bottom_left_y | FLOAT | 0.0 | Vertical offset of the bottom-left corner as a fraction of image height (-0.5-0.5) |
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| bottom_right_x | FLOAT | 0.0 | Horizontal offset of the bottom-right corner as a fraction of image width (-0.5-0.5) |
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| bottom_right_y | FLOAT | 0.0 | Vertical offset of the bottom-right corner as a fraction of image height (-0.5-0.5) |
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## Notes
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- All offsets are given as fractions of the image dimensions (0.0 = no shift, 0.1 = 10% shift). Positive x shifts right, positive y shifts down.
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- The transform uses bilinear interpolation to resample pixel values at non-integer locations.
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- For trapezoidal distortions (common in tilted AFM scans), typically only two corners need adjustment.
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- Set all offsets to 0.0 to pass the field through unchanged.
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