Overview

ChromaExplorer Screenshot normal vision aidScreenshot of Aid Mode in ChromaExplorerScreenshot of colorblindness simulationScreenshot of ChromaExplorer color test

ChromaExplorer is an app for exploring color vision and color blindness. It operates both as a tool for demonstrating color blindness to persons with normal color vision, and as an aid for persons with color blindness.

In Demo mode, ChromaExplorer simulates the three common types of color blindness – Protanopia, Deuteranopia, and Tritanopia — as well as monochromatic (colorless) vision. The input to the simulation is either video from the device’s camera or color-pattern test images.

In Aid mode, ChromaExplorer transforms images so that persons with any of the three types of color blindness can distinguish colors that they ordinarily cannot. Again, the images are either live video from the device’s camera or color-test images. With video input the color in a center target area of the image is identified for the color-blind user.

Now available for iOS.

Documentation

ChromaExplorer is an app for exploring color vision and color vision deficiency (CVD).

In Demo mode it demonstrates for persons with normal color vision the three common types of CVD – Protanopia, Deuteranopia, and Tritanopia, as well as monochromatic (“colorless”) vision.

In Aid mode it transforms images so that persons with any of the three common CVDs can distinguish colors that they cannot normally.

See below for a brief definition of the terms used here. For a more detailed explanation of how the demonstrations in chromaexplorer are created, go to our website by tapping ‘@’ below.

Demo Mode

In Demo mode you can view your device’s camera video input, as well as the test images, as experienced with any of the simulated types of color vision.

The left button in the second row cycles through the following input options:

  • Video
  • Protanope Test (“red/green blindness” type 1)
  • Deuteranope Test (“red/green blindness” type 2)
  • Tritanope Test (“yellow/violet blindness”)
  • Color Plane

The right button in the second row cycles through the following color demonstrations:

  • Normal (no color vision deficiency)
  • Protanopia: ‘R/G blind’ 1 (Red/Green)
  • Deutan: ‘R/G blind 2 (Red/Green)
  • Tritan: ‘Y/V blind’ (Yellow/Violet)
  • Monochromacy (“colorless” vision, only shades of gray)

To make a quick comparison, touch the display part of the screen to momentarily turn off the simulated deficiency and show the image with normal vision.

Aid Mode

Aid mode is designed to assist people with a CVD. In this mode images are processed by a color transformation to make distinguishable those hues that are indistinguishable to a person with any of the three CVDs.

You have the same choices of input as in Demo mode, but all input images are processed by the color transformation aid. You can turn the aid off momentarily by touching the screen.

With video input, a color wheel will appear in the center of the screen. Inside the wheel is a pointer that points at the actual color contained in the small circle at the center. The length of the pointer indicates the degree of saturation, and the width of the pointer indicates the brightness in the center.

Terms

Humans have three types of receptors in their eyes used for color vision that are sensitive to different wavelengths of light.

A person with Protanopia is missing the receptor sensitive to long wavelengths, which we normally perceive as the red portion of the spectrum. This makes it difficult to distinguish red from gray, for example.

A person with Deuteranopia is missing the receptor sensitive to medium wavelengths, which we normally perceive as the green portion of the spectrum. This makes it difficult to distinguish green from gray, for example.

Someone missing either of these two receptors also has difficulty distinguishing red from green and a range of colors, such as orange and yellow, that are encoded by the difference in activity between these two types of receptors.

A person with Tritanopia is missing the receptor sensitive to short wavelengths, which we normally perceive as the violet portion of the spectrum. This makes it difficult to distinguish violet from gray.

Someone missing this receptor type also has difficulty distinguishing violet from yellow and other colors that are encoded by the difference in activity between this receptor and the other two.

Someone missing two receptor types can only perceive shades of gray. Someone missing all three can still perceive shades of gray with the fourth class of light receptor, used for night vision.

Background

For an introduction to color vision, see:
http://www.scholarpedia.org/article/Color_vision

For an advice sheet for teachers:
http://www.colourblindawareness.org/wp-content/uploads/2010/07/Detailed-CVD-advice-sheet-for-teachers.pdf

For a more in-depth descriptions, see:
http://webvision.med.utah.edu/book/part-viii-gabac-receptors/color-perception/
http://www.oculist.net/downaton502/prof/ebook/duanes/pages/v8/v8c019.html

For a description of the opponent color space utilized in the Aid algorithm, see:
http://www.ncbi.nlm.nih.gov/pubmed/6512691

For an overview of color vision deficiency (“color blindness”), see:
http://www.colourblindawareness.org

For an in-depth description, see:
http://www.nature.com/eye/journal/v24/n5/full/eye2009251a.html

For a controversial new theory that addresses some persistent limitations of the standard theory, see:
http://conesandcolor.net