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.


Performance

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.


Simulated Vision

Sim Daltonism can simulate the vision of many forms of color blindness:

Red-Green
• Deuteranopia (no green cones)
• Deuteranomaly (anomalous green cones)
• Protanopia (no red cones)
• Protanomaly (anomalous red cones)
Blue-Yellow
• Tritanopia (no blue cones)
• Tritanomaly (anomalous blue cones)
All colors
• Monochromacy
• 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.