Edges
Laplacian
The Laplacian — contour without direction, thin and even.
Controls
- kernel
- Four looks along the sides only, eight also along the diagonals, which lays down twice the line on a slanted border
- threshold
- How strong the response has to be to count as an edge. High up the scale only the hardest borders survive
- blur
- Softens the picture before the edges are found. The second derivative hears noise loudly, and blur is what quiets it
- thickness
- A number from 1 to 4 pixels, 1 by default.
- contrast
- A number from -1 to 1, 0 by default.
- invert
- On or off, off by default.
- ink
- A colour, #ffffff by default.
- paper
- A colour, #000000 by default.