Photo to Coloring Page

How the line art is made

The photo is first reduced to brightness alone. Each pixel is then compared with the average of its neighbourhood (the Line detail radius): flat areas such as sky, skin and walls match their surroundings and turn white, while a pixel darker than its surroundings — the edge of a nose, a petal, a window frame — turns dark. That is the "colour dodge" trick behind every photo-to-sketch filter. For a coloring page the result is cut to pure black and white, tiny specks are deleted, and the outlines are thickened so a child's crayon can follow them.

Getting a clean coloring page

• Crop to the subject. Background clutter becomes clutter on the page. The Image Cropper takes seconds.
• Brighten dark photos first. Edges are found from contrast; an underexposed photo gives broken lines. Use Brighten Image, then come back.
• Start simple for young children. Line detail 10+, sensitivity around 30%, thickness 2–3 px and clean-up 150+ gives big, simple shapes.
• Go detailed for adults. Line detail 3–5, sensitivity 60%+, thickness 0–1 px keeps fur, leaves and fabric folds.
• Save as PNG. JPG adds grey fuzz around black lines; PNG keeps them crisp for printing.

Ideas that work well

Pets are the favourite — a dog or cat photographed against a plain wall comes out as a clear outline. Kids' own drawings photographed on paper clean up into tidy line art they can colour again. Family photos make personalised party activities and birthday cards; houses and cars make good gifts for their owners. For cutting machines, turn the finished line art into a vector with PNG to SVG, using its black-and-white preset.