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Color vision simulation
The simulator in the {doc}Accessibility Inspector <../index> in Firefox Developer Tools lets you see what a web page would look like to users with various forms of color vision deficiency (better known as "color blindness"), as well as contrast sensitivity loss.
"Color blindness" is a bit of a misnomer, since most people with these disorders can see colors, but do not see all of the distinctions that people with normal color vision can see; color vision deficiencies affect perception across the color spectrum, not only of specific colors like red or green. Color vision deficiencies affect about 8% of men, and 0.5% of women. The most common forms of color blindness (commonly lumped together as "red-green color blindness") affect more men than women, because they are due to a mutation in a gene in the X chromosome, which men usually have only one copy of.
Contrast sensitivity loss can be caused by cataracts, glaucoma, diabetic retinopathy, and other disorders of the retina; it can be age-related, congenital, or due to an injury.
:::{note}
This feature depends on webrender, an experimental featurethat is not enabled by default on all platforms. You can force-enablewebrender by settingthe preference gfx.webrender.all to true using the Firefox Configuration Editor (note that if webrender is enabled by default on your platform, the setting has no effect.
:::
The current color simulation option may be selected from the Simulate menu as shown.
:alt: 'Simulate menu in Accessibility panel. Used for selecting the simulation mode:
: None, Protanopia (no red), Deuteranopia (no green), Tritanopia (no blue), Achromatopsia
: (no color), Contrast loss'
:class: center
The following table shows a colorful image of a cat's face, and what it looks like in the each of the simulations.
.. list-table::
:widths: 50 50
:header-rows: 1
* - Simulation
- Image displayed
* - None (Choose this to return to normal display)
- .. image:: 28369550088_617db0d6f2_m.jpg
* - Protanopia (no red)
- .. image:: colorcat_protanopia.png
* - Deuteranopia (no green)
- .. image:: colorcat_deuteranopia.png
* - Tritanopia (no blue)
- .. image:: colorcat_tritanopia.png
* - Achromatopsia (no color)
- .. image:: colorcat_achromatopsia.png
* - Contrast loss
- .. image:: colorcat_contrastloss.png
:::{note} The simulation transformation matrices are based on the paper: A Physiologically-based Model for Simulation of Color Vision Deficiency, Gustavo M. Machado, Manuel M. OliveiraLeandro A. F. Fernandes, IEEE Transactions on Visualization and Computer Graphics, Volume 15 (2009). :::