Custom Convolution
Apply a user-defined convolution kernel to a DATA_FIELD. Enter rows of space-separated numbers. Equivalent to Gwyddion convolution_filter.c.
Inputs
| Name |
Type |
Required |
Description |
| field |
DATA_FIELD |
Yes |
Input field to filter |
Outputs
| Name |
Type |
Description |
| result |
DATA_FIELD |
Filtered field |
Controls
| Name |
Type |
Default |
Description |
| kernel |
STRING (multiline) |
"0 -1 0\n-1 5 -1\n0 -1 0" |
Kernel rows, each as space-separated numbers on a new line |
| normalize |
BOOLEAN |
True |
Divide the result by the sum of absolute kernel values to preserve amplitude |
| boundary |
dropdown |
reflect |
Boundary handling: reflect, nearest, or wrap |
Limitations
- Kernel must be a rectangle: all rows must have the same number of values.
- Maximum kernel size is 51×51; larger kernels are rejected.
- Non-finite values in the kernel are rejected and the input is returned unchanged.
- For large kernels, direct convolution can be slow; consider FFT Filter instead.
