Gradient Operators
Compare Sobel, Scharr, Prewitt, and Laplacian gradient operators with direction and output-strength controls.
First-derivative gradient operators are the foundation of edge detection. Sobel is the workhorse, Scharr offers slightly better rotational symmetry, Prewitt is a simpler unweighted alternative, and Laplacian is a second-derivative operator. Compare the four fixed 3×3 operators by direction and output strength.
How to Use Gradient Operators
- Upload an image: Upload one of the formats listed by the tool (JPG, PNG, WebP) and wait for the local preview.
- Adjust settings and process: Adjust the available controls, then run the selected image processing workflow in your browser.
- Review and download: Review the result, then download it in one of the formats offered by this tool.
Frequently asked questions
What is a gradient operator?
A gradient operator approximates the spatial derivative of an image: i.e., how fast intensity changes. Strong gradients indicate edges. Different operators (Sobel, Scharr, Prewitt) trade off noise sensitivity, rotational symmetry, and computational cost.
Sobel vs Scharr: which is better?
Scharr provides better rotational symmetry than Sobel. Its weights (10, 3, -3, -10) more accurately approximate a true gradient. Sobel (1, 2, 1) is faster and remains the most widely used. For high-precision tasks like optical flow, prefer Scharr.
When would I use Prewitt?
Prewitt uses unweighted neighbors (1, 1, 1 vs Sobel's 1, 2, 1). It's simpler and slightly more sensitive to noise but fine for educational comparison and lightweight detection.
What does Laplacian show?
Laplacian is a second-derivative operator. It highlights zero-crossings. Places where the gradient flips direction. Often combined with Gaussian blur for the LoG (Laplacian of Gaussian) edge detector.
Is the Gradient Operators tool free?
Yes. All tools on Pixlane are free with no signup required.
Does it reuse cached assets on repeat visits?
Browser caching can speed repeat visits; uncached site assets can still require an internet connection.
What image formats are supported?
JPG, PNG, and WebP are supported.