Getting started with Color by Number

Color by Number runs entirely in your browser. There’s nothing to install. Open colorbynumber.bearwoodlabs.com and you can start building a worksheet right away in demo mode.

Create your first worksheet

The app is a five step wizard. A row of cards across the top tracks where you are: Upload, Regions, Color key, Page, Export. Each card fills in with a status line once you’ve done the work, so you can see at a glance that you have a “1024x1024 image”, “81 regions”, “6 colors, 61 coded”, and so on.

Upload. Drop a PNG or JPG onto the drop zone, or use the “+ Upload image” button. Detection runs automatically as soon as the image loads.
Regions. The app finds the shapes in your artwork. Adjust the sliders and re-detect if it missed anything, or fix broken outlines with the repair tools.
Color key. Every region already has a code and a color. Paint any region a different color, leave regions blank, or move a label, right on the canvas.
Page. Set the title, instructions, and layout for the printed page.
Export. Download the worksheet and answer key as PNG, print them, or export an editable PowerPoint.

Step 1: Upload

Drop an image on the drop zone or use “+ Upload image”. Closed black outlines work best for line art, since the app traces those outlines to find each region’s edges. Solid black filled areas are treated like outlines too, so they won’t come out as a colorable region.

As soon as the image loads, detection runs on its own, usually in well under a second. If you upload line art, the app assigns a code and a color to each region using a graph coloring approach, so shapes that touch each other always end up with different codes. If you upload artwork that’s already colored in, it reads your fill colors instead and builds the key from those.

Step 2: Regions

The Region Setup panel gives you three sliders to retune detection if it didn’t come out right:

Line darkness controls how dark a pixel has to be to count as an outline.
Ignore regions smaller than (px) filters out tiny specks so they don’t turn into their own regions.
Colors (line art only) sets how many colors the auto palette uses, from 2 to 12.

There’s also a checkbox for “Code regions touching the edge (background)”. It’s off by default, so the background of the page stays uncoded and doesn’t get painted in.

Change a slider and click “Re-detect regions” to run detection again. Any manual colors, moved labels, and key edits you’ve already made are kept where possible, so you don’t lose your work by tweaking a setting.

If two shapes are leaking into each other because of a gap in the outline, use the Outline Repair tools instead of touching the sliders. Click “Start repair mode” to turn on the gap brush, then drag over the broken line to paint a seal across it. Regions update after each stroke. “Suggest repairs” will find likely gaps for you automatically, “Clear repairs” undoes your seals, and “Done repairing” exits the mode. When you’re happy with the regions, click “Next: edit color key”.

Step 3: Color key

The Color Key panel shows one row per color: swatch, code, name, how many regions use it, and a remove button. Click Edit on a row to pick from a preset palette, set a custom color, or use the eyedropper.

Three toolbar modes control what clicking the artwork does:

Paint region (the default) recolors whatever region you click to the currently selected key color.
Leave blank clears a region so it’s uncoded and unpainted, useful for backgrounds or parts you don’t want the student to color.
Move labels lets you drag a code label to a clearer spot inside its region.

To recolor something the auto palette got wrong, click the key row for the color you want, then click the region on the canvas. It repaints instantly and the counts on both rows update.

Above the canvas, a View dropdown switches between “Answer colors” (fully colored, the default), “Student outline” (black and white with number labels, exactly what the student will see), and a tinted view. Switch to Student outline any time to sanity check what’s about to print.

At the top of the panel, a Code style dropdown switches the codes between numbers (“1, 2, 3…”) and letters (“A, B, C…”). Under Advanced: custom region codes, you can give one key color more than one code, for example having 5+5, 6+4, and 7+3 all map to the same key entry. That turns any picture into a math facts worksheet, where solving the problem tells the student which color to use.

A Label size slider controls how big the printed codes are on the artwork. When you’re done, click “Next: format page”.

Step 4: Page

The Page panel is Worksheet Page Settings, with a live paper preview next to it. Toggle buttons above the preview switch between “Worksheet preview” and “Answer key preview” so you can check both before exporting.

Fields and options:

Title, Instructions, and an optional Footer credit / (c) line.
Page: Portrait or Landscape.
Key: Top, Bottom, or Hidden, for where the color key sits on the page.
Boxes: Plain, Crayon, or Pencil, which changes how the key’s swatch boxes are drawn.
Name & date line: on by default, adds “Name:” and “Date:” lines at the top of the worksheet.

The answer key page always includes the color key regardless of this setting, since a student needs the key on the worksheet but the teacher needs it on the answer page too. When the layout looks right, click “Next: export”.

Step 5: Export

The Export Bundle panel has four buttons: PowerPoint (.pptx), Worksheet PNG, Answer key PNG, and Print both. PowerPoint gives you an editable file with the worksheet and answer key on separate slides, handy if you want to add a cover slide or restyle it yourself.

Downloads are named from your title. A worksheet titled “Dinosaur Color by Number” comes out as dinosaur-color-by-number-worksheet.png and dinosaur-color-by-number-answer-key.png.

The exported worksheet is sized to US Letter proportions with the name and date line, centered title, instructions, the artwork with number labels, and the key box in the position you chose. The answer key page adds “Answer Key” after the title and shows the fully colored artwork with colored key swatches.