Olm Sketch for ComfyUI

An interactive sketching and drawing node for ComfyUI with stylus/pen support – built for fast, intuitive scribbling directly inside your workflows, geared towards ControlNet-style workflows which utilize scribbles and line art.

• Author: Olli Sorjonen
• GitHub: https://github.com/o-l-l-i
• X: https://x.com/Olmirad
• Version: 1.0.0

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✨ What Is This?

Olm Sketch is a lightweight and responsive drawing node for ComfyUI. It lets you sketch or scribble directly inside the node graph - perfect for fast iterations, ControlNet workflows, or simple markups.

No need to jump to a painting app - you can draw, adjust, and export images without leaving ComfyUI or evaluating the graph.

Use it for:

• Quick sketching inside i2i workflows
• ControlNet scribble guides
• Painting base ideas without launching external tools
• Immediate visual feedback and iteration

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🎨 Features

• ✍️ Interactive Drawing UI

  • Freehand and line tools
  • Line tool includes a dashed visual preview

• 🧰 Image Tools

  • Flip X / Flip Y
  • Rotate 90°
  • Invert colors
  • Crop using numeric inputs (L, R, T, B)

• 🌈 Flexible, Basic Brush System

  • Stroke width: 1–1024 px
  • Alpha opacity for painterly blending
  • Blend modes: source-over, multiply, screen, overlay, lighter, color-dodge, color-burn, xor

• 🎨 Color Picker

  • RGB/HEX/HSV color input
  • Eyedropper, sample colors from canvas

• 🖼️ Image Handling

  • Upload existing image directly into node (no graph eval needed)
  • Save your sketch anytime to the ComfyUI output folder (output/my_drawings by default)

• 🧠 Smart UX

  • Realtime, responsive canvas
  • Node auto-resizes to match image
  • Supports up to 2048x2048px (4K+ in future updates)
  • Compact UI layout for a clean graph experience

• 💡 Persistence

  • Images persist and can tolerate UI restart and backend restart
  • Permanently auto-saved images are stored to output/olm_sketch_cache
  • Temporary previous frames are saved to ComfyUI temp folder
    • Automatically culled during a session if you paint/sketch a lot (And ComfyUI restart flushes this dir)

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📦 Installation

1. Clone this repository into your custom_nodes folder.

   git clone https://github.com/o-l-l-i/ComfyUI-Olm-Sketch.git
   

   Your folder should look like:

   ComfyUI/
   └── custom_nodes/
       └── ComfyUI-Olm-Sketch/
           ├── __init__.py
           ├── olm_sketch.py
           └── ...
   

2. Restart ComfyUI to load the new node.

There are no extra dependencies - it works out of the box.

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🧪 Basic Usage

1. Add the Olm Sketch node from the node search menu.
2. Start drawing directly on the canvas in the node.
3. Use tool buttons and UI fields for crop, flip, rotate, etc.
4. To save your sketch, click the save button in the node.
   • Files are saved to ComfyUI/output/my_drawings/ by default.
   • You can change the output subfolder and filename directly in the node UI.
   • Alternatively you can of course render it out and use Save Image node.
5. Automatic saving happens when saving scenes/graphs and files go to ComfyUI/output/olm_sketch_cache/.
6. Upload an image via the built-in UI to draw on an existing base.

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⚠️ Known Limitations

• No built-in undo/redo support yet.
• 2048x2048 resolution limit (4K support planned.)
• No layer support - this is a lightweight sketch node, not a full painting suite.
• Very basic mask support - you can output an image as a mask (no overlay support or such yet.)
• Saved images are overwritten if using the same name (watch your filenames!)
• While I put effort to automatic save, do not trust it 100% yet.

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Pen support

• At least Wacom styluses seem to work; but very limited testing has been done so far.
• HTML color picker's eyedropper does not work at all with pen touch - map click (left) to a button to get around this issue.
• Pressure sensitivity did not function in browser (Chrome) when Windows Ink was disabled in Wacom settings.
• The pen controls sometimes start to fail and you can't adjust widgets.

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💬 Notes

This extension is experimental and under active development. Functionality, file formats, and behavior may change without notice, and compatibility with future updates is not guaranteed. Use at your own risk, especially in production workflows.

Back up your projects frequently. Feedback, bug reports, and suggestions are always welcome - but expect breakage, quirks, and rough edges. This tool does what I need right now; future updates may be irregular depending on available time.

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License & Usage Terms

Copyright (c) 2025 Olli Sorjonen

This project is source-available, but not open-source under a standard open-source license, and not freeware.

You may use and experiment with it freely, and any results you create with it are yours to use however you like.

However:

Redistribution, resale, rebranding, or claiming authorship of this code or extension is strictly prohibited without explicit written permission.

Use at your own risk. No warranties or guarantees are provided.

The only official repository for this project is: 👉 https://github.com/o-l-l-i/ComfyUI-Olm-Sketch

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Author

Created by @o-l-l-i