About ColoringZap
ColoringZap is a free tool that turns one of your own photos into a black-and-white coloring page you can print. It runs entirely in your browser.
What it does
You choose a photo — JPG, PNG, or WebP — or drop one onto the page. The tool draws it to a canvas and converts it: grayscale, then a Gaussian blur, then Sobel edge detection, then a threshold that keeps the strong edges as black lines on a white background. The result is shown next to the original so you can compare.
Four controls let you tune the output:
- Edge Detail — how much of the picture becomes a line. Higher means more lines.
- Smoothness — how much the photo is blurred before edges are looked for. Helps with grainy or noisy photos.
- Line Width — 1 to 4 pixels, so the outlines suit crayons, markers, or fine pencils.
- Dark Background — for photos taken against a dark background, where the subject is lighter than its surroundings.
When you are happy with it, you download it as a PNG or send it straight to your printer.
What it does not do
ColoringZap does not generate new pictures. No image model is drawing anything — the tool only traces the edges that are already in the photo you supplied. If the source photo is busy, low-contrast, or cluttered, the outlines will be busy too. That is what the sliders are for, and a photo with one clear subject against a plain background gives the cleanest result.
Who it is for
Parents and teachers who want a coloring sheet made from a real picture: a pet, a family photo, a child's own drawing, a holiday snapshot, a class mascot. Also anyone who wants a printable outline quickly without installing software, creating an account, or handing a personal photo to a website.
Why it runs in your browser
Because a photo of your family or your classroom does not need to sit on somebody else's server. There is no upload step, no account, no watermark, and no daily limit. The trade-off is that the page only holds the image while the tab is open — if you want to keep a coloring page, download the PNG.
The full detail is written out in our Privacy Policy.
Who makes it
ColoringZap is made by the ColoringZap Team.
How it is built
The site is served by a single Cloudflare Worker. The generator is plain JavaScript and HTML canvas — no framework, no build step in the browser, and no fonts or images loaded from other domains. It works in desktop and mobile browsers that support canvas.
Get in touch
Questions, bug reports, or requests: see the Contact page.