Color blindness simulation in real time for iOS apps
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.gitignore Initial commit Sep 9, 2014
LICENSE Updated README Sep 12, 2014


Vangogh is an iOS library for testing how well an application works for people with various kinds of color vision deficiencies.

It lets you interact with your app as you normally would while applying one of several color transformations to the user interface in realtime.

Tested on Xcode 5 and iOS 7


The repo comes with a simple demo that opens Flickr in a webview:

An example video of the demo in this repo

(gfycat for slow connections)


  1. Clone the repo with git clone
  2. Copy and add Vangogh.h and Vangogh.m to your project
  3. Replace your app's UIWindow-based key window with an instance of VGWindow
  4. Add an import for the Accelerate.framework if needed
  5. Run your app and shake the device (Cmd-Ctrl-Z on the Simulator) to activate filtering


Vangogh uses a CADisplayLink to periodically take a snapshot of the running application and then uses the Accelerate.framework to multiply the image with a filter matrix. The resulting image is displayed in a separate window that passes through any touch events. The framerate is capped to 30 FPS by default.

While a filter is active a details view displays the current type of color blindness and how common it is for males and females. You can switch filters by tapping the arrow buttons and pause the current filter by tapping between them. You can also limit filtering to one side of the screen by panning from the middle of the view to the left or right.

You can dismiss the details view by swiping it downwards. Shake the device again to stop filtering completely.

The filters are based on values from this archived page.


  • The details view is always shown in portrait orientation
  • There might be issues when running on iOS 8 beta devices


All source code is licensed under the MIT License. See the LICENSE file for more info.