> ## Documentation Index
> Fetch the complete documentation index at: https://dripart-mintlify-b90d3c69.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.
# Canny - ComfyUI Built-in Node Documentation
> Complete documentation for the Canny node in ComfyUI. Learn its inputs, outputs, parameters and usage.
Extract all edge lines from photos, like using a pen to outline a photo, drawing out the contours and detail boundaries of objects.
## Working Principle
Imagine you are an artist who needs to use a pen to outline a photo. The Canny node acts like an intelligent assistant, helping you decide where to draw lines (edges) and where not to.
This process is like a screening job:
* **High threshold** is the "must draw line standard": only very obvious and clear contour lines will be drawn, such as facial contours of people and building frames
* **Low threshold** is the "definitely don't draw line standard": edges that are too weak will be ignored to avoid drawing noise and meaningless lines
* **Middle area**: edges between the two standards will be drawn together if they connect to "must draw lines", but won't be drawn if they are isolated
The final output is a black and white image, where white parts are detected edge lines and black parts are areas without edges.
## Inputs
| Parameter Name | Function Description | Data Type | Input Type | Default | Range |
| ---------------- | --------------------------------------------------------------------------------------------------------------- | --------- | ---------- | ------- | --------- |
| `image` | Original photo that needs edge extraction | IMAGE | Input | - | - |
| `low_threshold` | Low threshold, determines how weak edges to ignore. Lower values preserve more details but may produce noise | FLOAT | Widget | 0.4 | 0.01-0.99 |
| `high_threshold` | High threshold, determines how strong edges to preserve. Higher values only keep the most obvious contour lines | FLOAT | Widget | 0.8 | 0.01-0.99 |
## Outputs
| Output Name | Description | Data Type |
| ----------- | ----------------------------------------------------------------------------------------------- | --------- |
| `image` | Black and white edge image, white lines are detected edges, black areas are parts without edges | IMAGE |
## Parameter Comparison
**Common Issues:**
* Broken edges: Try lowering high threshold
* Too much noise: Raise low threshold
* Missing important details: Lower low threshold
* Edges too rough: Check input image quality and resolution
> This documentation was AI-generated. If you find any errors or have suggestions for improvement, please feel free to contribute! [Edit on GitHub](https://github.com/Comfy-Org/embedded-docs/blob/main/comfyui_embedded_docs/docs/Canny/en.md)