VISIT

1
VIS-IT
VIS-IT is a tool designed to teach individuals
about colour vision deficiencies. For a person
suffering from a colour vision deficiency,
everyday tasks such as watching the weather
forecast or even reading a webpage can become
near to impossible. VIS-IT allows users to upload
their own images and view them how a person
suffering from a Protanopia, Deuteranopia or
Tritanopia colour vision deficiency views them.
The 3 Steps to filtering
Open an image The user can either select an image
from our pre-existing library or choose to upload
an image from their own computer.
1.
Colour Vision Deficiencies Protanopia,
Deuteranopia and Tritanopia are all forms of
Dichromacy colour deficiency where
photoreceptors of a specific colour (red, green
or blue) are either not functioning or absent
within the retina. Those with Dichromacy
(Dichromats) may see certain colours without any
problem, they may however, confuse certain
colours depending on the form of colour
deficiency they suffer.
Protanopia Those who suffer from protanopia
confuse the colours red and green due to
missing/malfunctioning red photoreceptors. This
form of colour deficiency is present in 1 of
all males and in less than 1 of all
females. Deuteranopia Those who suffer from
deuteranopia are similar to those who suffer from
protanopia in that they confuse the colours red
and green however those who suffer deuteranopia
confuse colours because of missing/malfunctioning
green photoreceptors. This form of colour
deficiency is present in 1 of all males and in
less than 1 of all females.
Choose A Filter The user selects a filter to
apply to the image in order to view the image how
a person suffering from a color deficiency sees
the image.
2.
Colour Spectrum Taken from http//www.internettg.
org/newsletter/mar99/accessibility_color_challenge
d.html
Apply filter The filter is applied to the
original image and a new filtered image
is displayed. Filtered images can then be saved
or printed.
3.
Tritanopia A very rare form of colour deficiency
where an individual can perfectly perceive red
and green however has troubles distinguishing
between the colours blue and yellow. This form of
colour deficiency is present in less than 1 of
all males and in less than 1 of all females.
Possible Extensions We plan to extend VIS-IT in
the following ways HTML Parser- This will allow
designers to check that their work is accessible
to people with colour vision deficiencies. ClearVi
ew- Create a clear window that filters anything
placed under it by the selected filter. The user
can drag the window around the desktop in order
to see how the Operating System and other
applications are viewed by people suffering with
colour vision deficiencies
The Filtering Process The filtering works by
running an algorithm over each pixel of an
image. The algorithm is based on one developed by
Brettel, Viénot and Mollon, which converts RGB
pixel values into their LMS equivalent using a
transformation matrix. Then the LMS values are
corrected for the type of colour vision
deficiency with some simple vector multiplication
and converted back to RGB for redisplaying. The
LMS co-ordinates are the Long, Medium and Short
wave colour receptors in the eye. The types of
colour vision deficiency we are dealing with
correspond to one of those receptors not
functioning. The algorithm removes the
non-functional receptor and replaces it with the
reduced stimuli version.
VIS-IT has been designed and Implemented
by Bader Buallay - Computing and Accounting and
Finance. Christopher Frost - Computer
Science. Sophia Rainford - Computing and
Philosophy.