Boondoggle

Painting by numbers

Draws an image into the background of a spreadsheet.

This was originally a learning project for Apache POI, now rewritten in Python.

For an example output, check demo_sheet.xlsx.

Quick Start

From ghcr.io

You can run this direct from the container registry with:

docker run -p 9731:9731 ghcr.io/metriccaution/boondoggle:latest

From Source

The quickest and easiest way of trying out this project is with Docker Compose, then go to http://localhost:9731/docs:

docker-compose up --build

If you have uv installed, you can also run:

uv run fastapi run server.py

Dev Mode

To run the server watching source code for changes, run it as:

uv run fastapi dev server.py

Command-Line Tool

There is also an included tool for converting a directory of images into a single workbook:

uv run cli.py ./path/to/images/ masterpiece.xlsx

Operation

In simple terms, an image is read, pixel by pixel and the background colour of a single cell is filled in that colour.

Some image compression is done to make this take a sane amount of time

• Scaling images - Restricting the resolution of an image limits the number of cells which need writing.
• Colour quantisation - Each cell style is an entity within an XLSX file, by restricting the number of colours, and reusing these styles for each colour, write time is (significantly) reduced.