Question 1

How does the sketch effect work?

Accepted Answer

The tool uses Sobel edge detection — a computer vision algorithm that finds edges in an image by detecting rapid changes in pixel brightness. It computes horizontal and vertical gradients, combines them, then inverts the result to produce dark lines on a white background, mimicking a pencil sketch.

Question 2

Why does my image look different from what I expected?

Accepted Answer

The sketch effect works best on images with clear edges and good contrast — portraits, architecture, objects. Images with fine textures, gradients, or low contrast may produce unexpected results. Try adjusting the intensity slider to control how strongly edges are detected.

Question 3

Does this tool work offline and keep my images private?

Accepted Answer

Yes, completely. All image processing happens in your browser using the Canvas API. Your image is never uploaded to any server. Once you close the browser tab, no trace of your image remains. This tool works fully offline after the page loads.

Question 4

What image formats are supported?

Accepted Answer

The tool accepts any image format supported by your browser: JPEG, PNG, WebP, GIF (first frame), AVIF, and BMP. The output is always saved as PNG to preserve the quality of the sketch lines.

Question 5

Why is my output image limited to 800px?

Accepted Answer

The tool limits processing to 800px on the longest dimension for performance. Larger images take significantly longer to process in the browser. If you need full-resolution output, you can process the image in multiple crops or use desktop image editing software like GIMP with a Sobel filter.

Image Sketch Effect

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