Everything you need to know about Canny
Canny is a sophisticated edge detection algorithm that produces clean, thin, connected lines. It uses a two-threshold system (hysteresis) to identify strong edges and connect weak edges that are linked to strong ones. This results in more accurate and continuous outlines compared to simpler edge detectors.
Parameters
- Strength
Controls how much of the edge effect is blended into the image. At 0, no change is visible. At 1.0, you see the full edge detection result. - Low Threshold
The minimum gradient strength for a pixel to be considered a potential (weak) edge. Lower values detect more edges but may include noise. - High Threshold
The minimum gradient strength for a pixel to be considered a definite (strong) edge. Weak edges are only kept if they connect to strong edges. - Blur
Pre-smooths the image before edge detection. Higher values reduce noise and produce cleaner edges, but may miss fine details. - Softness
Controls the sharpness of the threshold transitions. At 0, edges are hard black/white. Higher values create anti-aliased, smoother lines. - Output
Overlay draws the detected edges on top of your original image (darkening where edges are). Edges Only produces a pure black-and-white edge map. - Invert
Swaps edge direction – in Overlay mode, edges lighten instead of darken. In Edges Only mode, displays dark edges on a white background instead of white on black.
Tips
- Keep Low Threshold lower than High Threshold for proper hysteresis
- Start with defaults, then adjust thresholds to balance detail vs. noise
- Use higher blur for noisy photos to get cleaner outlines
- Great for creating line art, technical illustrations, or artistic sketches