CoByN .
Colour by Number. Pictures in, vector outlines and numbers out — posterised to your pencil count, every flat area a region, every region its number. Sister lab to Mosaic.
Images
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Page
Sheet sizes — one page set per size
A3 (poster)
11 × 17 Tabloid
A4
8.5 × 11 Letter
8.5 × 8.5
8 × 10
7 × 10
6 × 9
5 × 8
A5
Margin (mm)
Orientation
Guide / key sheet size
Guide orientation
No text on art sheets (no footer)
Tone
White cut-off snaps near-white pixels to pure white — cleans off-white paper before posterising.
Sheet background
Mode
Two tones are detected — paper and ink. The lighter tone is the paper and stays blank; every separated ink shape becomes a region.
Invert — treat the darker tone as paper
Number every separated region
Repeat the number across large regions
This picture looks monotone — Mode ▸ Monotone gives cleaner regions.
The lines are…
Dark pixels become filled vector shapes. Line weight below adds extra thickness to the traced ink.
Colours
Palette
Leave the background white and unnumbered
Background is the border colour that is…
Border-touching regions within this ΔE of the main background colour are treated as background too — needed for gradient backdrops.
Choosing a brand? Sarah Renae Clark's colored pencil comparison (Affiliate link) tests all three. Pencil hex values via Jenny's Crayon Collection.
Lines
Line colour
Solved page keeps its lines in the line colour (otherwise black)
Rounding
Numbers
Number colour
One size for every number. A region that can't hold it is left unnumbered and counted in the summary.
Pages per size
Line art page (outlines only)
Number page (guide — number colour above)
Art number page (numbers in the line colour)
Solved page
Key page
One-sheet guide (numbers + colour list)
Reverse-colouring overlay (transparent, outlines only)
Digital Colour Cube ↗Affiliate link
Preview .
Load a picture to build its sheets.
No picture yet.
Size set
Edit regions .
Click a region to open its options. Drag to pan, ⌘/Ctrl + wheel to zoom. Edits stick to this picture.Region
Assign to colour
The Tray .
The Tray — unlock with All-Access
Turn one design into a whole batch of colourways, bank up to 120 tiles as you go, and grab them all in a single ZIP.
Wrap it Your Way — easy peasy.
Get access
Single-file downloads stay free.
Bank each picture's page set into an output group, then grab the lot as one ZIP with a pageset.json manifest your book builder reads in order.
Output group
ZIP contents
SVG + 300 dpi PNG
Pool by output type
Export .
This sheet as a file, every sheet as one ZIP of PNGs (a folder per size), or the whole set to your printer as a PDF. Single files stay free; the Tray above banks sets for ZIP.
Print dialog: Scale 100%, Margins None — the paper size is set for you.
Single pages are free. The whole set and the Tray come with All-Access. Send to Book Lab is free — books under 24 pages download free; 24+ pages (KDP-ready) unlock with the Book-making set.
Poster .
Poster sets — unlock with All-Access
Wrap it Your Way — easy peasy.
Get access
Single pages up to A3 / Tabloid stay free.
Print one picture big, tiled across A4 or A3 sheets. Numbers and lines stay their true size — a bigger poster just gives every region more room.
Poster size
Print on
Poster shows
True size
Numbers print at the Number height you set; lines at the Line weight.
Poster orientation
Load a picture to plan the poster.
Poster
Print dialog: Scale 100% (Actual size), Margins None. Page 1 is the assembly map and key.