🎨 Coloring Book Stencil Generator

Upload an image and get a numbered coloring-book stencil + color preview

Photos, or drawings in PNG, JPG, WEBP or SVG. A vector drawing is rendered to pixels first, at a size chosen for the grid you asked for, and then goes through the same engine as everything else — so it comes out sharper than the same drawing exported by hand at the wrong size.
Or start from an icon set
Adding your own artwork PNG, JPG, WEBP or SVG, one file per subject, or a ZIP of them — each file becomes one icon named after it, so name the files before zipping. Flat colour on a plain background works best: the engine reduces each picture to the 24 pencils, and a photograph or a heavy gradient comes out as speckle. Transparent backgrounds are flattened onto white. A pack is yours, so nothing in it needs a credit line.
One or more words. It decides which of the sources beside this have anything to offer, and how many.
Icon source
What can be uploaded A Drive file link, not a folder — share a ZIP of the icons. SVGs need filled paths, not strokes; images need a clear silhouette, transparent or dark on light. An icon font (.ttf/.otf) becomes a pack of its own — every glyph is one icon, and a fill-only font has no outline variants to sift. Two fill-only fonts ship with the app and are listed above already. You can also drop folders and fonts into appdata/coloring-book/icons/ on the NAS: each one shows up here on its own, no upload needed.
Colours
Colour names or a hex code. Two or more names set the whole palette; one name or one hex joins what is there.
Cover overlay
How to export one Export your finished cover from your design tool as a PNG with the background layer hidden, then add it here. Every background is then previewed underneath the real design.
Millimetres added between the two halves of a wrap. A saddle-stitched booklet folds rather than having a spine, so leave this at 0.
Matching neighbours is the share of touching tiles allowed the same colour. 0 keeps every edge visible; higher lets some merge, which looks less mechanical.
Cover preview
Draw a mandala
Geometry rather than a drawing: the rings, the symmetry and every facet are computed, so the lines are always closed, no region is too small to colour, and the colours come from the same 24-pencil pack.
⬆ Upload your own mandala artwork
Which reading of the artwork's colour is right depends on the artwork, not on anything the app can measure about it — so it is a choice rather than a guess. Standard is the 24-pencil pack most pages are already drawn from, matched as the colours actually are. Vivid is the same 24 pencils, but pushes a muted colour toward its nearest hue instead of its nearest grey — worth trying when Standard reads as mostly one or two colours. Muted is a different, smaller set of dusty tones built for artwork that is soft-coloured to begin with, and reads closer to that kind of source than either of the others — but it shares no colours with the 24-pencil pack, so a page drawn with it needs its own key or its own box if it goes in a book with the rest. Pick All three to draw one of each from the same picture and decide by looking, without uploading it three times. Artwork is a separate question from colour: it picks how the picture is cut into areas. Mandala keeps every pocket of paper the lines enclose and folds the page onto its own mirror axes, which is right for a pattern where every pocket is there on purpose. Drawing is for a peacock, a lion, an elephant — it has no axis to fold onto, and where three strokes meet the pen leaves a speck of paper that is a junction rather than a shape, so those are absorbed into the line instead of printed as tiny numbered blobs.
⤓ Bring in pages from the studio
Everything the studio still has. A page brought in here is rebuilt into an ordinary mandala page — its own facets, its own colour key, the same 24 pencils — so it can be edited, erased, recoloured, combined and put in a book like any other. The picture it was read from comes with it, so Read from a picture in the editor can cut the same artwork again with the engines here and the two readings can be compared side by side. With Remove from the studio ticked, what came over is deleted there (a page that failed stays); untick it to leave the studio as it is, in which case bringing the same page in twice makes two pages.

Pattern-fill pages

Upload a plain line-art outline (black lines, white fill — no numbers, no grid) and each fully-enclosed white area is filled with a random hatch pattern instead of a color-by-number cell. A decorative activity page on its own, not part of the numbered stencils.

No files chosen
Fill a shape with pattern
✋ Place mandalas or patterns by hand
Pick a picture first.
The picture gives the outline and the areas inside it — a mane, an ear, a paw — and each area is filled separately. Two kinds of picture work: your own outline, drawn in lines on white (PNG, JPG or SVG), where every area the lines close off is filled on its own and the lines themselves come back as the printed outline; and flat colour artwork, where each colour is an area. A photograph is neither, and has no areas to find. Nothing is saved until you keep it, and a kept page lands in the gallery below with every other page, so it goes into a book the same way. Mandala fills each area from its own edge inward and puts a rosette in what is left in the middle, so every line in it follows the edge of the area it is in and nothing runs across the picture. Tick as many traditions as you like: two areas that meet never take the same one. An area the artist has already drawn inside — a wrinkled head, a mane — keeps its own drawing and takes no ornament over the top of it. Patchwork fills each area with flat geometric blocks — half-squares, flying geese, chevrons, fans — cut off at the line where the next area starts. It is patchwork rather than ornament and answers to no tradition, so the Ornament picker steps aside for it; rows draws from one tradition, walking the shape's own edges and following them inward. Place mandalas by hand is the other way round: you pick the areas, and those areas become a window on to one mandala you choose, slide and scale yourself. What falls inside the window is drawn and the rest of the mandala is not there. Place as many as you like, one set of areas at a time, and let the fill do whatever you have not placed yourself. Density sets how many regions there are to colour — at the low end a page of a few dozen large ones, which is what a child's book wants, and at the high end several hundred. Eyes, nostrils and the like are found in the picture and left clear either way.

Books you have made

Every book is kept when it is built, so you can have it again without rebuilding it — that takes a minute and needs the same pictures still tagged the same way.

Pinch to zoom · two fingers to pan

In this image

Rest of the 24-colour pack

Whole-page colour

In this mandala
Rest of the pack
Pinch to zoom · two fingers to pan