Blind Tip Estimate
Blind tip estimation from a measured SPM image using the Villarrubia algorithm. Iteratively refines the tip shape using only the sharpest image features without knowing the true surface in advance.
Inputs
| Name |
Type |
Required |
Description |
| field |
DATA_FIELD |
Yes |
Measured SPM surface image |
Outputs
| Name |
Type |
Description |
| tip |
DATA_FIELD |
Estimated tip shape (apex = maximum value, edges = 0) |
| certainty |
IMAGE |
Map marking surface pixels where the tip was in unambiguous single contact |
Controls
| Name |
Type |
Default |
Description |
| n_pixels |
INT |
33 |
Tip grid size in pixels (odd values only, 3–129) |
| threshold |
FLOAT |
0.0 |
Noise floor in metres; increase if the estimated tip is unrealistically sharp |
| method |
dropdown |
partial |
partial: uses local maxima only (faster, needs sharp isolated features); full: uses all points above morphological opening (slower, more robust) |
| use_edges |
BOOLEAN |
False |
When enabled, also uses image edge pixels as refinement candidates |
Limitations
- Requires sharp, isolated features on the surface for reliable results.
- Output tip has the same pixel size as the input field; tip deconvolution requires matching pixel sizes.
- Large tip sizes (n_pixels > ~65) or the full method on large images can be slow.
- Equivalent to gwy_tip_estimate_partial / gwy_tip_estimate_full + gwy_tip_cmap.
