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+# Parameter Reference
+
+This page documents the detection parameters defined in `scanslicer/params.py` (`AutoslicerParams.SPECS`).
+
+## Notes
+
+- All values are integer-backed.
+- Some parameters are context-sensitive and only apply to specific detection modes.
+- Internal safeguards:
+  - `aspect_ratio_max` is clamped to be `>= aspect_ratio_min`
+  - `canny_high` is clamped to be `>= canny_low`
+
+## Choice Parameters
+
+- `detect_pipeline`
+  - `0`: Threshold pipeline
+  - `1`: Canny pipeline
+- `bw_method` (threshold pipeline only)
+  - `0`: Simple threshold
+  - `1`: Adaptive Gaussian threshold
+  - `2`: Otsu threshold
+- `invert_mode`
+  - `0`: Auto (try normal polarity, then inverted fallback)
+  - `1`: Off (normal polarity only)
+  - `2`: On (force inverted polarity)
+- `morph_op`
+  - `0`: None
+  - `1`: Dilate
+  - `2`: Erode
+  - `3`: Open
+  - `4`: Close
+
+## Full Table
+
+| Parameter | Default | Range | Step | Used In | Effect |
+|---|---:|---|---:|---|---|
+| `detect_pipeline` | `0` | `0..1` | `1` | global | Select threshold or Canny detection pipeline. |
+| `clahe_clip` | `0` | `0..40` | `1` | preprocessing | CLAHE contrast boost (`0` disables). Effective clip limit is `value/10`. |
+| `gaussian` | `0` | `0..100` | `1` | preprocessing | Gaussian blur kernel size (`0` disables). Even values are bumped to odd. |
+| `bw_method` | `0` | `0..2` | `1` | threshold pipeline | Selects Simple, Adaptive Gaussian, or Otsu thresholding. |
+| `bw_thresh` | `210` | `0..255` | `5` | threshold+simple | Binary threshold cutoff. |
+| `bw_gauss` | `64` | `0..1000` | `2` | threshold+adaptive | Adaptive block size basis. Converted to odd and at least `3`. |
+| `bw_adaptive_c` | `2` | `-20..20` | `1` | threshold+adaptive | Adaptive threshold subtraction constant. |
+| `canny_low` | `50` | `0..255` | `5` | Canny pipeline | Lower Canny hysteresis threshold. |
+| `canny_high` | `150` | `0..255` | `5` | Canny pipeline | Upper Canny hysteresis threshold. |
+| `invert_mode` | `0` | `0..2` | `1` | global | Controls polarity inversion behavior before contour extraction. |
+| `morph_op` | `1` | `0..4` | `1` | global | Morphological operation on mask/edges. |
+| `contour_approx_pct` | `0` | `0..50` | `1` | contour extraction | Polygon approximation epsilon percentage (`value/1000`). |
+| `bbox_min_size` | `2` | `0..100` | `1` | contour filtering | Minimum candidate area as % of full image area. |
+| `bbox_max_size` | `90` | `1..100` | `1` | contour filtering | Maximum candidate area as % of full image area. |
+| `bbox_fill_thresh` | `10` | `0..100` | `1` | contour filtering | Minimum contour fill ratio within min-area box (%). |
+| `expected_count` | `0` | `0..20` | `1` | scoring/autotune | Expected number of photos (`0` means auto/unbounded heuristics). |
+| `aspect_ratio_min` | `100` | `100..1000` | `5` | contour filtering | Minimum long/short aspect ratio, scaled by `x100`. |
+| `aspect_ratio_max` | `400` | `100..1000` | `5` | contour filtering | Maximum long/short aspect ratio, scaled by `x100`. |
+| `border_ignore` | `0` | `0..20` | `1` | contour filtering | Ignore candidates touching image edges within this margin (%). |
+| `iou_merge_thresh` | `30` | `0..100` | `1` | contour dedup | Merge overlap threshold as IoU percentage. |
+| `dilate_kernel` | `30` | `0..500` | `1` | morphology | Morph kernel size for selected morph operation (`0` disables morphology). |
+
+## Advanced Parameters in UI
+
+The UI can hide/show advanced controls. Advanced set:
+
+- `detect_pipeline`
+- `clahe_clip`
+- `gaussian`
+- `bw_adaptive_c`
+- `invert_mode`
+- `contour_approx_pct`
+- `bbox_max_size`
+- `aspect_ratio_min`
+- `aspect_ratio_max`
+- `border_ignore`
+- `iou_merge_thresh`
+
+## Practical Tuning Guidance
+
+- Too many tiny false positives:
+  - Increase `bbox_min_size`
+  - Increase `bbox_fill_thresh`
+  - Increase `iou_merge_thresh`
+- Missed photos:
+  - Lower `bbox_min_size`
+  - Broaden `aspect_ratio_min/max`
+  - Try `detect_pipeline=1` (Canny)
+  - Try `invert_mode=2`
+- Border/frame artifacts:
+  - Increase `border_ignore`
+  - Switch morphology operation/kernel
+- Uneven illumination:
+  - Use adaptive mode (`bw_method=1`)
+  - Enable modest `clahe_clip`