Olli Sorjonen Debuts ComfyUI-Olm-SplineMask for Precise Image Masks

ComfyUI-Olm-SplineMask is a custom node for ComfyUI that enables users to draw precise masks using spline shapes. Instead of painting masks with a brush, users define areas by placing points to create editable polygons or smooth curves.

Developer Olli Sorjonen released the tool to provide a middle ground between messy manual painting and complex auto-masking solutions like SAM. This approach allows for the creation of clean, reusable selections directly within the node interface.

Precision masking tools

• Interactive spline editor for drawing and editing points.
• Support for multiple independent mask shapes in a single node.
• Optional Catmull-Rom smoothing for soft, curved edges.
• Live preview rendered directly onto the image canvas.
• Adjustable Gaussian blur and invert options for refined output.

Editors and designers who need exact control over image masking will find this node useful for creating consistent selections. By using mathematical curves rather than painted pixels, the masks remain sharp and editable, making the tool particularly suitable for projects requiring repeated adjustments or high precision.

Current limitations and support

The creator notes that the tool currently functions only on the old-style legacy LiteGraph-based UI. While newer UI updates exist, Sorjonen states he does not have the time to port the code immediately.

'Releasing this as-is since it’s functional and may still be useful to others!'

he explained in the release notes. Users should be aware that mask drawing is constrained to image bounds and the node does not yet support boolean operations like union or intersect. The installation requires no external dependencies, running on standard PyTorch and NumPy libraries.

ComfyUI-Olm-SplineMask can be found on GitHub.