Chroma: Real-Time Color Vision Deficiency Testing

Introduction

An estimated 300 million people worldwide have some form of color vision deficiency. This highlights just how critical colorblind-inclusive design is in modern software and games. The most common types of color vision deficiency are Deuteranopia, Protanopia, and Tritanopia. Each affects how individuals perceive either red, green, or blue hues. Addressing these forms during development helps ensure color isn’t a barrier to understanding or interaction.

April 2025 Ubisoft unveiled Chroma, an open-source accessibility tool for Windows. Chroma revolutionizes accessibility tooling by providing a way to test games with simulated colorblindness in real-time. Before Chroma, simulating color vision deficiency for games was typically a tedious manual process.

Our team at Accessibility Labs had the pleasure of experiencing Chroma’s announcement live at Game Accessibility Conference (GAconf). Jawad Shakil, Chroma’s Product Manager at Ubisoft, dove into its features and provided a demonstration. In this article we discuss the origins of Chroma, the challenges it solves, and how to set up and install it. We are thrilled at the release of this new accessibility tooling and applaud the efforts of Ubisoft in creating an open-source tool for designers, developers, and testers to improve the accessibility of their creations.

Origins

The concept arose when Ubisoft’s test team, “The Worldwide QC Accessibility Team” based in Bucharest, Romania, was faced with 3 challenges:

• Accurate algorithm to simulate color vision deficiency
• Real-time viewing, no frames are missed
• The ability to control the game while simulating filters

Before Chroma, their team and other game accessibility testers were limited to taking screenshots of high impact areas and applying filters to the screenshot. There were no real-time assessment tools, at least not publicly available.

Development of Chroma began in 2021, led by Ubisoft India Studios in Pune, with close collaboration from the Bucharest-based accessibility team. Game accessibility specialist Ian Hamilton and Ubisoft’s Director of Accessibility, David Tisserand, provided guidance on the tool’s requirements. The tool was iterated over several internal projects before its open-source release in 2025.

“Over the past few years, Chroma has proven to be a highly efficient tool for us at Ubisoft. It has allowed us to assess the accessibility of our games for colorblind players much faster and more comprehensively than ever before. Because we believe accessibility is a journey, not a race, we’re thrilled to share Chroma with the entire industry. We invite everyone to benefit from it, provide feedback, and contribute to its future development.”

– David Tisserand, Ubisoft Director of Accessibility

Chroma is released under the Apache 2.0 license and hosted on GitHub, allowing developers to freely integrate it into their workflows or contribute improvements back to the community.

How Does Chroma Work?

Chroma was built to address the three core challenges identified by Ubisoft’s accessibility QA teams. The result is a flexible overlay tool that allows developers and testers to simulate color vision deficiencies seamlessly.

Color Oracle Algorithm

Through rigorous testing of multiple algorithms, Ubisoft discovered that Color Oracle was the most accurate. Color Oracle consistently topped benchmark charts and closely matched real world conditions.

Color Oracle is a well-known open-source simulator developed by researchers Bernie Jenny and Nathaniel Kelso. Color Oracle uses scientifically validated models of color perception. By basing Chroma on the Color Oracle algorithm, this ensured the color filtering closely mirrors what actual colorblind players experience.

Real-Time Simulation

Chroma simulates color vision deficiency in real-time using an overlay. With an overlay, frames are not impacted or missed. Testers can observe live gameplay, cinematics, or UI transitions under the filter at 60 frames per second. This increases efficiency, by reducing the need to recreate specific game scenarios. This also empowers testers to notice fine details that may have been overlooked with the approach of screenshotting-then-filtering.

Uninterrupted Game Input

Further enhancing efficiency, testers are able to interact with their target application while the overlay’s simulation is running. This allows testers to stay focused on the application without switching back and forth between windows. The tool supports a toggle between “Tool” mode (for resizing and filter selection) and “Game” mode (for direct input), letting testers freely interact with the application while viewing it through the color simulation filter.

Additional Features

• Dual Screen Support: Chroma supports both single and dual-screen setups.
• Hotkeys: Users can assign hotkeys to operate Chroma
• Screenshotting: Screenshots showcase default and simulated images side-by-side
• Resizable Overlay: Chroma’s window can be resized to suit your needs

How To Set Up Chroma

Chroma is a lightweight tool, with a download size of roughly 23MB and 155MB once installed. It’s compatible with Windows 10 or later.

1. Download Chroma on GitHub. (23.2 MB)
   • To download, select the Code dropdown and Download Zip
   • Alternatively, for just the application without additional files, download Chroma’s setup executable under “…” More File Actions.
2. Run Chroma_setup.exe to Install (155.5 MB)
   • Complete the installation wizard, establishing install location and shortcut creation
3. Open the application you wish to simulate color vision deficiency with. Ensure it is not minimized or hidden.
4. Launch Chroma, a window named “UbiChroma” will appear.
5. Right-click the window. A selection menu of your PC’s open applications will be listed.
6. Select the target application for colorblindness simulation.

After selection, Chroma will appear as a “clear” window displaying your application within it. This is because no filters have been applied yet. The window can be repositioned, resized, or right-clicked again to switch target applications. This is the extent of the window’s functionality. From here, you’ll use the System Tray to apply filters and control Chroma’s settings.

How To Use Chroma

Chroma is launched and focused on your target application. To adjust the filter, control game input, and assign hotkeys, access Chroma in your System Tray. System Tray is typically located on the bottom right of the Windows Taskbar.

To review Chroma’s options, right-click the icon in System Tray. This will open a menu of selections. Selections include: Filter, Input, Hide, Help, Options, About, and Exit.

• Filter modifies Chroma’s simulated viewport. Default, Deuteranopia, Protanopia, Tritanopia, and Grayscale filters are provided.
• Input selects which application receives input controls. By default, Tool is selected each launch. While Tool is selected, Chroma’s target application can be modified and the window size and placement can be adjusted. When Game is selected, your target application can be interacted with; the Chroma window can no longer be modified.
• Hide causes the window to disappear. Hotkeys are still active.
• Help redirects to Chroma’s User Guide.
• Options opens a window allowing the user to configure hotkeys. Hotkeys include Screenshot, Screenshot Path, Tool and Game input toggle, and each Filter.
• About displays version number, copyright, and contact.
• Exit quits Chroma.

When opening Options, initially all hotkeys are blank allowing the user to customize them. The ability to remap the hotkeys is great when considering game controls may conflict. Hotkey modification allows the user to avoid overlap. Overall, hotkeys increase the efficiency of testing without the need to continually activate the system tray icon.

Hotkeys must include Alt, Ctrl, or Shift in combination with a number or letter key. These are the hotkey assignments our team at Accessibility Labs found intuitive to use:

Note: Most of our hotkeys are based on their English control name and may not translate.

• Tool Screenshot: Ctrl + 1
• Tool and Game Screenshot: Ctrl + 2
• Change Input: Alt + C
• Default: Shift + R (think ‘Reset’)
• Protanopia: Shift + P
• Deuteranopia: Shift + D
• Tritanopia: Shift + T
• Grayscale: Shift + G

Screenshots

While screenshotting isn’t available directly through the System Tray, it becomes enabled once a hotkey is assigned. Screenshots are especially helpful when communicating color-related issues to team designers and developers.

• Tool Screenshot captures your application in your current Chroma filter.
• Tool and Game Screenshot captures a side-by-side view: the default image on the left, and your selected filter on the right.

Each screenshot includes labeling in the bottom-left corner to identify the applied filter. These labeled screenshots are great for bug reports and visual documentation. Below, we provide example screenshots from the opening of Blue Prince.

Conclusion

In this guide, we’ve explored the challenges that led to Chroma’s creation, how it solves them, and the features that make it a standout accessibility tool.

Although Chroma was built for games, its applications extend far beyond. It’s just as useful for reviewing video infographics, refining visuals in design software, and ensuring clarity in educational content. Anyone working with color can benefit from what Chroma offers.

At Accessibility Labs, we’ve already integrated Chroma into our workflows and have seen how much it streamlines colorblindness testing. If you’re looking to improve accessibility in your products, we’d love to help. Accessibility Labs provides testing services including color accessibility assessments.

We hope you enjoy exploring Chroma and using it to create content that communicates. If you’d like a partner in that process, feel free to reach out. We’re just a message away.