From the perspective of a color blind person, some colors are impossible to distinguish. Sim Daltonism lets you visualize colors as they are perceived with various types of color blindness.
Move the Sim Daltonism window over something on the screen and see what it looks like with a color blindness. With this app you can check the accessibility of websites and other user interfaces, make your visual designs better for color blind people, or just play around to better understand how various color blindness types affect color perception.
The Filter Window
The Sim Daltonism window acts as a filter for what is under it. You can click inside and manipulate windows from other apps that are located under it.
But you can change this so the filter window follows the mouse pointer, displaying the area around it. This makes it possible to view the filtered image alonside the unfiltered one.
Sim Daltonism is fast enough to filter a video in real time or to have many filter windows active simultanously.
If needed, you can reduce or increase the refresh speed to save energy or improve responsiveness.
Sim Daltonism can simulate the vision of many forms of color blindness:
• Deuteranopia (no green cones)
• Deuteranomaly (anomalous green cones)
• Protanopia (no red cones)
• Protanomaly (anomalous red cones)
• Tritanopia (no blue cones)
• Tritanomaly (anomalous blue cones)
• Partial monochromacy
Note that the colors shown are only an approximation. Color blindness varies from person to person and the simulator cannot represent everyone’s vision. Many other factors can affect the results, such as the automatic white point calibration of the camera. Nevertheless, Sim Daltonism is a good tool to better understand color blindness.
Sim Daltonism is open source and is also available for iOS.
• Corrected an issue with the filter where some saturated blues would incorrectly become purple.
Ratings and Reviews
Absolutely critical tool for inclusive design
I've been using a version of Sim Daltonism for what seems like forever. I recommend it to anyone who actually cares about accessibility and inclusive design.
It's small, lightweight, and just works beautifully. It's an indispensible tool in my design arsenal.
The fact that I can use this as a layer over Sketch and Xcode - or projects online for review is amazing. Don't sleep on the iOS version, either!
Indispensable tool for checking design against CVD
I use and highly recommend SD to my design colleagues as it provides a completely independent and non-intrusive overlay to similuate how users with color vision deficiencies see the interfaces we're building, and if they'll notice the differences in state change.
My only problem with the app is that it doesn't seem to currently handle the dark mode in macOS correctly, which causes the icons used for controlling the type of CVD simulated to become essentially invisible (black icons on a black toolbar). It's an ironic oversight, and I kind of have to guess where the icons are, usually hitting the refresh-rate menu instead. Should be a simple fix, so I hope the developer can take a minute to update the app.
Developer Response ,
I'm glad you like this app, but I can't replicate your dark icon problem on my end. Please send me an email if you want to investigate this further.
Simple to use and very effective
More designers should take into account the perspective of colorblind people.
I wonder if this application should provide some more knowledge for the user, such as :
* which types of colorblindness are more common than others
* how colorblindness works and why the colors change the way they do for each type
Data Not Collected
The developer does not collect any data from this app.
Privacy practices may vary, for example, based on the features you use or your age. Learn More
- Michel Fortin
- 5 MB
- Graphics & Design
- Requires macOS 10.10 or later.
- Age Rating
- © 2005-2020 Michel Fortin
With Family Sharing set up, up to six family members can use this app.