Turn a photo or cartoon into a clean coloring page: closed black outlines on white, with Style, Detail and Line weight controls, saved as PNG or printable PDF.
There are two ways to find the lines, one per style, and one way to draw them. Cartoon traces the drawing itself. A picture under 1600 pixels on its long side is first enlarged two to four times with smooth interpolation, so thin strokes can be followed. Two kinds of line are then found and joined: the artwork's own dark outlines, which are pixels clearly darker than the colours on both sides of them, and edges between clearly different colours, such as a white cloud on blue sky, found with a Canny edge detector on the colours. The joined lines are thinned to a single centre line one pixel wide, so a drawn outline and the colour edge beside it become one line, not two. Short spurs and specks are removed. Photo cuts the picture into areas: grain and texture are smoothed away, the colours are grouped into 24 main colours, and areas that differ only softly, like the bands of a smooth sky, or are too small are joined. A line goes wherever two areas meet, so every shape is closed. Both styles draw every line with a round pen of one width, solid black with soft edges, on white.
Style is Auto, Cartoon or Photo. Auto looks at how much of the picture is flat: when at least 45 percent of pixels are in the same colour box as all four of their neighbours, it is treated as flat art and gets Cartoon, otherwise Photo. The preview says which one Auto chose. Detail runs from 1 (less) to 5 (more). In Cartoon it sets how strong a colour edge or how dark an outline must be to become a line, and how short a line may be. In Photo it sets the smallest area kept: on a 1800 by 1200 photo, Detail 3 keeps any area of 1728 pixels or more, Detail 1 needs four times that and Detail 5 a quarter. Line weight sets the width of every line: Fine is 2 pixels, Medium 3.5 and Bold 6 on a picture 1800 pixels on its long side, scaled to the picture and never under 1.5 pixels, so a 900 pixel picture gets 1.5, 1.75 and 3. Small pictures are drawn larger and shrunk, which keeps their lines smooth.
Cartoons, clip art, logos and drawings with flat colours give the cleanest pages, with every character and shape outlined. For photos, a clear subject against a plain background works best: toys, pets, fruit, buildings. Busy scenes such as crowds, grass or rocky shores become many small shapes; lower Detail to keep only the big ones. Two touching things of the same colour, with no line between them in the picture, may share one outline. The page is made at no more than 1800 pixels on its long side; a larger picture is made smaller first and a smaller one is not enlarged. The live preview is made from a copy at most 800 pixels long, with the same steps and sizes scaled to it, and shows how much of the page is ink, with a note below 0.15 percent or above 30 percent. The printable PDF puts one picture on each page of A4 or Letter inside a half-inch margin, turned to landscape when the picture is wider than tall. Print at actual size.
The photos are opened and turned into line art by code running in your browser. There is no upload step and no server that receives them. The page counts visits with Google Analytics, using rough groups such as 1 to 10 MB, never a file name or an image. Photo details such as location and camera model are not in the result, because the page is drawn fresh from the lines. You can add up to 50 photos at once, about 500 MB in total on a computer or 150 MB on a phone, and they are processed one at a time to keep memory use low.
Add the picture, check the preview, and press Make coloring page. The tool outlines every area of colour in black on white. Leave Style on Auto, or pick Cartoon or Photo yourself. If the page is too busy, lower Detail; if shapes are missing, raise it. Then save the PNG or switch Save as to Printable PDF.
Cartoon follows the drawing: it keeps the artwork's own outlines as single clean lines, plus edges between clearly different colours, so eyes, pupils, mouths and ears stay. Photo first smooths grain and texture and outlines the main areas of colour, so a photo gives closed shapes rather than scribbles. Auto picks Cartoon when at least 45 percent of the picture is flat colour.
Every line is drawn with a round pen at least 1.5 pixels wide, so its middle is solid black; only the outer edge is softened so it looks smooth when printed. Fine lines are 2 pixels wide on an 1800 pixel picture, Medium 3.5 and Bold 6.
Choose Printable PDF and pick A4 (210 by 297 mm) or Letter (8.5 by 11 in). Each picture becomes its own separate one-page PDF, with the picture inside a half-inch margin, in landscape when the picture is wider than tall. In the print dialog choose actual size or 100 percent, not fit to page, so the margin stays.
Small shapes come from texture and fine detail in the picture. Lower Detail to 1 or 2, or for a photo keep Photo style, which smooths texture first. Missing lines usually sit between colours that are nearly the same; raise Detail to 4 or 5, or try the other Style.
No. The pictures are turned into line art by code running in your browser, and nothing is uploaded. The page counts visits with Google Analytics using rough size groups such as 1 to 10 MB, never a file name or an image. Your style, detail and line weight settings are remembered in this browser.