Sobel Edge Detection

Highlight edges using the classic 3×3 Sobel operator.

Tool Media & Files Updated Apr 19, 2026
How to Use
  1. Drop image.
  2. Pick threshold / invert.
  3. Download.
Image
Drop image
Preview

Notes

Gx
[-1,0,1;-2,0,2;-1,0,1]
Gy
[-1,-2,-1;0,0,0;1,2,1]
Magnitude
√(Gx²+Gy²)
Threshold
Edge/no-edge cutoff
Output
PNG grayscale
Privacy
Local

About the Sobel Edge Detection

Working on image, audio and file tasks? The Sobel Edge Detection is a free browser tool that gives you the answer in seconds. Highlight edges using the classic 3×3 Sobel operator.

How it works

Enter what you have and read the result as it updates live. It all runs on your own device, so it is quick and private, with nothing to install.

Want the deeper story? The Knowledge Base explains the ideas behind the tools in more detail.

Frequently Asked Questions

Algorithm?

Sobel 3×3 X + Y gradients; magnitude = √(Gx² + Gy²).

How do I use the Sobel Edge Detection?

Simply type your numbers and read the result, which refreshes the instant you change something. There is nothing to submit and nothing to wait for.

Do I need to install or sign up for anything?

Not at all — it runs in the browser with nothing to install and no account. After it loads once, it even works without an internet connection.

Is my information private?

Yes. Everything happens in your browser. Nothing you type is sent to a server or saved anywhere.

Common Use Cases

Sketch effect

Line art from photo.

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