Image Outline Extractor - Free Online | ToolXHub

After uploading the image, the tool uses Sobel or Canny edge detection algorithms to scan areas of sudden changes in brightness in the image and extract the outline into a line sketch with a black line and a white background. The sensitivity threshold for edge detection can be adjusted. The lower the threshold, the more details will be extracted, and the higher the threshold, leaving only the main contours. You can also adjust the thickness and color of the lines.

All calculations are completed on the browser side and no pictures are uploaded. The algorithm first grays the image and reduces the noise through Gaussian blur, then calculates the gradient amplitude, and finally determines the output binary contour map through threshold values.

Suitable for converting photos into draft lines for painting reference, coloring book making, and pretreatment before logo transfer. It is also often used in educational scenes to convert physical photos into outlines for students to fill in colors.

The online image contour extraction tool extracts line contours in the image through edge detection algorithms to generate line draft effects, and can adjust the sensitivity and line thickness.