phomo

phomo turns a folder of images into the building blocks of a photographic mosaic. It is best suited to people comfortable working with Python or a command line who want to control how tiles are matched and reused. Its appeal is a free, configurable desktop workflow; its main tradeoff is that it is not a browser-based creator.

Overview

The tool recreates a master image by arranging tile images into regions. Install it with pip to use it as a Python package, or run the phomo command with a master image and a directory of tiles. That flexibility works well for local workflows, particularly when you want to use your own tile library, but the command-line approach is a poor fit if you expect a graphical editor.

Key features

phomo compares tile images with regions of the master by color distribution, then assigns tiles using a linear sum assignment algorithm. Its matching options include greyscale, norm, and luv_approx distance metrics, color equalization, and ways to match color distributions. These controls let users adjust the matching process rather than rely on a single fixed approach.

The CLI can crop and resize the master and tile images, convert images to black and white, display the grid, and set how often a tile appears. Custom tile libraries and tile reuse controls give users room to shape a composition around their source collection. The output format is PNG.

A greedy tile assignment option improves performance at the expense of accuracy. It makes sense when speed matters more than the closest match; for a job where fidelity is the priority, the standard assignment approach is the more suitable choice. CUDA acceleration is available through an extra, but requires both a CUDA-compatible GPU and the CUDA toolkit, so it is not a plug-and-play speed boost for every desktop.

The package requires Python 3.9 or newer, but below 3.13. It is published under the MIT License; PyPI identifies Loic Coyle as its author and lists one maintainer.

Pricing

phomo is free: its sole plan, phomo, costs nothing and includes the Python package and CLI utility. There is no free trial because access is already free. The plan has no listed seat or quota limits; CUDA acceleration is conditional on having compatible hardware and the toolkit. This is a straightforward option for individual users and developers who can work with the tool directly, rather than buyers seeking a paid support tier or managed service.

Platforms

phomo is a desktop utility for Linux, macOS, and Windows. The package requires a supported Python version, and CUDA use adds GPU and toolkit requirements. That makes it a fit for users comfortable setting up a local software environment, not people who want to create mosaics entirely in a browser or on a phone.

Who it's for

Choose phomo if you have a collection of tile images and want to control image preparation, matching, and tile reuse in a local workflow. Python users can integrate the package into their work; command-line users can operate it with a master image and tile directory. Look elsewhere if you want a visual, browser-based creation process or prefer a service built around printing and downloads.

Pros and cons

• Pros: Free access to both a Python package and CLI makes it useful for script-based and command-line workflows without a purchase.
• Pros: Multiple distance metrics, color-distribution options, and image controls provide meaningful ways to tune the mosaic and its source images.
• Pros: Custom tile libraries and reuse controls support compositions built around a chosen collection.
• Cons: The command-line and Python workflow requires technical comfort and is less suitable for users expecting a graphical editor.
• Cons: The faster greedy assignment option sacrifices accuracy, while CUDA acceleration depends on additional hardware and software.

Alternatives

Photo Mosaic Software is the category directory for comparing mosaic tools. AndreaMosaic is another free desktop option, with a Standard plan capped at 200 megapixels, 30,000 tiles, and 50,000 images, plus creation and printing features. Picture Mosaics Online Mosaic Tool suits users who want web, iOS, or API access and free creation with an account; downloads, prints, and video files are paid. EasyMoza is a web choice with free low-resolution downloads and a paid XL option for larger JPG output.

Rapid-Mosaic offers free Windows software for local creation and online print ordering. Photo Mosaica is another option for iOS and macOS. PhotoMosaic.ai offers web-based creation with an always-free plan and 4,800×4,800px output. Mosaicify Studio is a free web tool with no sign-up and high-resolution downloads. PicTiler offers a free service with standard-quality output for personal and commercial use.

Verdict

phomo is a strong choice for Python and command-line users who want a free local mosaic tool with adjustable matching and tile reuse. Its main reason to choose it is control over the tile-assignment workflow; its main reason to look elsewhere is the lack of a graphical or browser-based creation experience.