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Edge Detection

Find every edge in a photo with a Sobel filter and a live strength slider.

Detect edges in an image

Download edges PNG
Working size: No image loaded
Filter: —
The Sobel filter runs on a local canvas, so your photo is never uploaded.

How to use the Edge Detection

  1. Choose the photo whose edges you want to detect.
  2. Set the edge strength with the strength slider.
  3. Pick dark or bright edges and download the PNG file.

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Frequently Asked Questions

Common questions about the free online edge detection.

Choose a photo, set the edge strength and pick dark or bright edges, then download the result as a PNG.
No. The filter runs on a canvas inside your browser, so your photo never leaves your own device.
The Sobel operator measures the brightness gradient in both directions, then combines them into a single edge strength value.
Dark edges on white suit printing and tracing, while bright edges on black give a neon outline effect.
Raise the strength slider to make faint edges visible, and lower it when the outlines start to look noisy.
Yes. Edge detection is a classic first step for computer vision, background removal and line art recolouring.
The result is grey, so you can use it as a mask or overlay in any editor and tint it however you like.
Yes. The edge detection tool is fully responsive and works in any modern browser on phones, tablets and desktop computers.
Yes. It is completely free and unlimited, with no account, no sign-up and no watermark on your downloaded image.

Last updated: October 10, 2026