Sobel Edge Detection

Highlight edges using the classic 3×3 Sobel operator.

Tool Media & Files Updated Apr 19, 2026
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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

Frequently Asked Questions

Algorithm?

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

Common Use Cases

Sketch effect

Line art from photo.

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