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SPECIAL VISION NEEDS
LIGHT SOURCE

WHY DO WE NEED IT?

People with defective color vision need aids to identify colors.

Here are some examples of how defective color vision causes troubles:

1. People assembling electronic components can't read the color codes identifying the various parts. They insert the wrong parts, because they can't tell the different color codes apart. Repairmen have the same troubles.
2. Artists make paintings that unintentionally contain colored objects with the wrong colors.
3. Room decor looks very different to others than intended.
4. Clothing that appears to match to the wearer does not match.
5. Color codes used to identify objects are misidentified.
6. Reading railroad, aircraft, airport, ship, and traffic signal lights requires good color vision.

WHAT CAN BE DONE?

People with defective color vision need special lights or filters to identify colors.

Since the person can see the colored light reflected from objects, but cannot distinguish some colors from others, special lights or filters are needed to identify the colors. There are several different methods, depending on the type of color vision defect:

• The RGB method for protanomaly, deuteranomaly, and tritanomaly.
• The separate colors method for protanopia, deuteranopia, tritanopia, and other defects where colors are misidentified.
• The added color method for any of the color vision defects.

WHAT CAN BE USED?

• For protanopia, deuteranopia, tritanopia, and red-green indistinction:
  1. Colored filters that change the relative lightness or darkness of a selected group of colors (compared to other colors) can be alternately be placed in front of the eyes and taken away.
  2. Colored lights that change the relative lightness or darkness of a selected group of colors (compared to other colors) can be alternately be turned on and turned off, or can be arranged to blink on and off. This is the added color method.

     A special remote-control RGB bulb is available that can be set to several different colors or can be set to rotate through multiple colors.

  3. Special glasses with different filters in the left and right lenses. They trade ability to detect different colors for some loss of depth perception.
  4. Special colored lights with different colors coming from the left and right of the viewer can let the viewer determine different colors by turning the object to the left or the right (or viewing both sides of a round object simultaneously).

     This is useful for reading color codes on electronic parts.

• For protanomaly, deuteranomaly, and tritanomaly:
  1. Colored filters that change the relative lightness or darkness of a selected group of colors (compared to other colors) can be alternately be placed in front of the eyes and taken away.
  2. Colored lights that change the relative lightness or darkness of a selected group of colors (compared to other colors) can be alternately be turned on and turned off, or can be arranged to blink on and off. This is the added color method.

     A special remote-control RGB bulb is available that can be set to several different colors or can be set to rotate through multiple colors.

  3. Special glasses with different filters in the left and right lenses trade ability to detect different colors for some loss of depth perception.
  4. Special colored lights with different colors coming from the left and right of the viewer can let the viewer determine different colors by turning the object to the left or the right (or viewing both sides of a round object simultaneously).

     This is useful for reading color codes on electronic parts.

  5. In many cases, tri-color color television provides the correct cues for normal color vision. Most tri-color TV systems do not produce wavelengths that are wrongly perceived.

     The Sharp Quattron 4-color system can NOT provide this advantage.

  6. Special color filters or glasses that contain sharp notch filters that remove light in the yellow and cyan regions of the spectrum, but not other colors, can allow the anomalous vision system to see the correct colors by removing wavelengths that are wrongly perceived.

     A company called EnChroma makes glasses with these notch filters that turn anomalous color vision into nearly normal color vision.

     This works with railroad, aircraft, airport, ship, and traffic signal lights.

  7. Special colored lights that have gaps in the yellow and cyan regions of the spectrum, can allow the anomalous vision system to see the correct colors by not producing wavelengths that are wrongly perceived.

     The special remote-control RGB bulb (above) can do this when set to white.

     The Visi-Spectrum lights you can build here do this.

The Visi-Spectrum Light

Available Lamps

This is based on the fact that the person has three types of color-sensing cones. By restricting the sensations to the three primary colors, this simplifies the sorting of the colors. In some cases of anomalous color vision, the person will see the colors that people with normal color vision see.

The spectra shown are artificial images based on spectra obtained by the methods shown here:
Build a Spectroscope

The problem is finding a source of light with red, green, and blue wavelengths, but with no other colors present. Here are some of the products available in 2013 that can be used:

The RGB Method

Choosing lamps for the various kinds of color blindness

There are three kinds of color vision defects:

1. Anomalous trichromatic vision, where one or more cones have the wrong color response

   This includes protanomaly, deuteranomaly, and tritanomaly.

2. Dichromatic vision, where one cone type is missing or two cone types appear identical

   This includes protanopia, deuteranopia, tritanopia, and red-green indistinction.

3. Monochromatic vision, where only one cone type works, or only rod vision works

   This includes monochromatism (only blue cones) and cone blindness.

The following lamps or lamp combinations are useful:

• Color TV

  The color TV system actually stimulates the cone cells in predictable ways. It can be used to show a person with anomalous trichromatic vision what the world looks like to others.

  A color television screen can be used as a light source for observing other colors, but it probably will not provide enough light.

  A digital camera and its viewing screen might provide normal color views in the same way.

• Tricolor LED

  This lamp by itself can provide the necessary stimulus separation needed for true color vision with anomalous trichromatic vision.

  The switchable multicolor LED will work for this when set to white. This device allows the flexibility of turning the lamps on and off independently. Doing this can help identify some colors (the switching works with all types of color blindness).

• Triphosphor CFL

  This lamp by itself might provide the necessary stimulus separation needed for true color vision with anomalous trichromatic vision.

• Daylight CFL

  This lamp by itself might provide the necessary stimulus separation needed for true color vision with anomalous trichromatic vision. It is a cheap alternative to the others if it works.

  It might not work because it has spectral lines in the orange and yellow-green parts of the spectrum. So it depends on the actual color anomaly present.

• Bicolor Yellow CFL and Blue CFL

  These two lamps together provide the red, green, and blue bands necessary to aid anomalous trichromatic vision. Just be sure any yellow bulb used is a bicolor lamp, instead of a yellow phosphor lamp or a filtered white CFL. Use a pair of diffraction grating "rainbow" glasses to find out.

  Note that the bicolor yellow CFL does NOT work as a no-bug light, even though it is sold for that purpose. Because it emits green light, it attracts bugs as much as a white light will.

• Separate Red, Green, and Blue Party Lamps.

  These lamps together provide the necessary stimulus separation needed for true color vision. They have the ideal wavelengths.

  This allows the flexibility of turning the lamps on and off independently. Doing this can help identify some colors (works with types of color blindness other than cone anomaly).

  The special remote-control RGB bulb can be used here.

A separate white light can be added for times when color identification is not important.

The Separate Color Method

Choosing lamps for protanopia, deuteranopia, tritanopia, and other defects

The following lamps or lamp combinations are useful:

• Separate Red, Green, and Blue Party Lamps.

  These lamps together provide the necessary stimulus separation needed for true color vision for anomalous trichromatic vision. They have the ideal wavelengths.

  This allows the flexibility of turning the lamps on and off independently. Doing this can help identify colors (and works with other kinds of color blindness).

  The special remote-control RGB bulb can be used here.

• Separate Red, Green, and Blue Party Lamps, plus a white lamp.

  These lamps together provide the necessary stimulus separation needed for true color vision. They have the ideal wavelengths.

  This allows the flexibility of turning the lamps on and off independently. Doing this can help identify colors (and works with other kinds of color blindness).

  The white lamp is used when color identification is not required.

  The special remote-control RGB bulb can be used here.

The Added Color Method

Choosing lamps for color identification

The following lamps or lamp combinations are useful:

• Use ordinary white light, with one or more colored lamps to identify colors

  The white light is used for ordinary work. When the user needs to separate two colors, he turns on one of the other lamps to separate one color from another.

  The color of each lamp is determined experimentally. The user chooses the color that does the best job of separating the colors for his purposes.

  This method works for any kind of color blindness.

  The special remote-control RGB bulb can be used as a colored source.

BUILDING A LAMP ARRAY

Selecting the color circuits needed

The complexity of the system you make depends on your needs. For some, only one combination of lighted lamps may be needed. For others, many different circuits may be used. Here are some suggestions of what to use:

1. The RGB Method
   • Tricolor LED (Including the special remote-control RGB bulb)
   • Triphosphor CFL
   • Daylight CFL
   • Bicolor Yellow CFL and Blue CFL
   • Separate Red, Green, and Blue Party Lamps
   • A separate white light can be added for times when color identification is not important.
2. The Separate Color Method
   • Separate Red, Green, and Blue Party Lamps.
   • A separate white light can be added for times when color identification is not important.
3. The Added Color Method
   • Ordinary white light, with one or more colored lamps to identify colors
   • User chooses the color that does the best job of separating the colors.
   • If the color needed is not available as a bulb, a white bulb with a color filter can be used.

Designing a fixture

Any of the following can be used to provide a fixture to hold the lamps:

• A wall-mount fixture with many sockets, rewired for multiple circuits
• Several wall-mount fixtures with many sockets, one for each lamp color
• A chandelier or two, with many sockets, multiple circuits, used with a white ceiling
• Track lights with multiple circuits
• Multiple-bulb floor lamps rewired for multiple circuits
• Theatrical vanity mirror light strips with multiple circuits
• Multiple gooseneck desk lamps
• Individual rosette lamp sockets with individual switched circuits
• Anything else you might already have handy

Wiring the circuits for the lamps

The following lamp fixture wiring methods can be used:

• A portable fixture can be built with multiple lamp sockets and a pendant control box for switching the various kinds of lamps (top diagram).
• Permanent wiring can be used with gang boxes for multiple toggle switches and multiple porcelain rosette sockets on round boxes for the individual lamps (bottom diagram).
• Permanent wiring can also be used with gang boxes for multiple toggle switches and multiple track lighting sets for the individual lamp circuits (bottom diagram).
• Translucent diffusers can be used to blend the light from the bulbs. But diffusers must be checked, to be sure they do not block or darken some colors. Also check what happens to the diffuser when exposed to ultraviolet light. Some plastics become brittle or turn yellow.
• Cove lighting with a known white ceiling can diffuse the light.

The following lamp fixture wiring methods can be used:

• A portable fixture can use a pendant control box for switching the various kinds of lamps (top diagram above, and at right).
• A portable fixture can be built with individual pull-chain switches to turn on and off the various kinds of lamps (top diagram above, without the cable).
• A portable fixture can be built with a rotary switch to select the various kinds of lamps. Separate switches are needed for the blue CFL, the Soft White LED, and the blacklight CFL, so they can be combined with other sources.
• Permanent wiring can be used with gang boxes for multiple toggle switches.
• The page author's switch box is shown at right.

The Author's Setup

Here is the page author's flat-spectrum setup.

The page author used an old store display fixture he got at a store-closing sale for a dollar to build a flat-spectrum light source. The same kind of fixture can be used for the special vision needs fixture.

The switchbox is designed to switch four kinds of lamps:

FLAT SPECTRUM		LAMP POSITION	SPECIAL NEED
LAMP COLOR	SWITCHES		LAMP COLOR	SWITCHES
Daylight CFL	CFL	Positions 1 and 8	Daylight CFL	CFL
Soft White LED	WARM	Positions 3 and 5	Red CFL	RED
Daylight LED	COOL	Positions 4 and 6	Green CFL	GREEN
Blue CFL	BLUE	Positions 2 and 7	Blue CFL	BLUE

Photos of what the lamps look like when on, with approximate spectral distribution:

DISPLAY	PHOTO	SPECTRUM	CFL	WARM	COOL	BLUE
All lights off			OFF	OFF	OFF	OFF
Blue on			OFF	OFF	OFF	ON
CFL on			ON	OFF	OFF	OFF
Flat-spectrum (All but CFL)			OFF	ON	ON	ON
All lights on			ON	ON	ON	ON
An updated version of this fixture is at BUILD A FULL-SPECTRUM LIGHT SOURCE
The fixture above could be used instead to switch red, green, blue, and white lamps. The photos below are altered in color, because the author does not have the colored lamps.
DISPLAY	PHOTO	SPECTRUM	CFL	RED	GREEN	BLUE
All primary on			OFF	ON	ON	ON
All lights on			ON	ON	ON	ON
CFL with Added Red			ON	ON	OFF	OFF

Additional Tools

The charts at the right can be used to help the user identify colors. Print them on a color printer. Then look at them under the special vision lights to see what the colors are supposed to look like.

 
 
 
 

The upper chart has the primary colors of light:

• Red is at the top
• Blue is at the lower left
• Green is at the lower right

The circles overlap to produce the secondary colors, with white in the center:

• Cyan is at the bottom
• Magenta is at the upper left
• Yellow is at the upper right

The lower chart has a range of colors:

1. Magenta
2. Cerise
3. Red
4. Orange
5. Yellow
6. Leaf
7. Green
8. Aqua
9. Cyan
10. Azure
11. Blue
12. Violet

Color filters can also be used to help identify colors.

SIMULATING DEFECTIVE COLOR VISION

Build a lamp array to show people with normal color vision how colors appear to the color blind.

The lamp array contains the following colors of lamps.

• Red - Must be a nearly monochromatic red emitting no other colors.
• Yellow - Must be a nearly monochromatic yellow, emitting no red, orange, or green.
• Green - Must be a nearly monochromatic green, emitting no orange, yellow, or cyan.
• Blue - Must be a nearly monochromatic blue, emitting no other colors.

Additional lamps may be used to simulate more cases:

• Orange - Must be a nearly monochromatic orange emitting no other colors.
• Cyan - Must be a nearly monochromatic cyan, emitting very little green.

Use the following settings to simulate various kinds of color vision.

†   A white light can be used here.
‡   The EnChroma glasses could be used instead of no filter.

THE PAGE AUTHOR'S 2016 SIMULATOR FOR DEFECTIVE COLOR VISION:

The page author had the good luck to find another used light bar with 6 sockets, so he built the color-blindness simulator. He used a switchbox (below) and an 8-conductor cable between the switchbox and the lamp. Colored LED bulbs were used.

For some reason, the author's camera will not auto-adjust for brightness with nearly monochromatic lights in the field of view, so it was impossible to take a good photo with any lamps on. The photo had severe halation (scattered light fogging the photo). So the first photo shows the lamps turned off. The second photo is the first photo altered with added color to make the lamps look turned on.

The lamp array contains the following lamps (left to right).

• illumin8 Red LED
• illumin8 Orange LED
• illumin8 Yellow LED
• illumin8 Green LED
• Feit Blue LED (for cyan)
• illumin8 Blue LED

All of these lamps except the Feit Blue have extremely narrow bandwidths. This makes the simulation work quite well. A few objects in the room might look wrong because they reflect a very narrow bandwidth of light. Fortunately, this is not usually the case, and most objects will have the expected color to be seen under these lights.

The page author used the color grids made for the web page The Crayon Trials as sample colors to compare under the simulations of the different color vision defects.

The light bar switching is wired as shown at right.

The switches are wired to quickly show the differences between normal vision and 11 different color vision defects, using only one switch to show the difference in most cases:

The following table shows the switch positions needed for each vision defect. The - means center off:

This light bar can also be used (in a Normal Vision setting) for the visi-spectrum light.

2017 EPILOG:

All of the colored LED products in this article were no longer sold by stores in my area in September 2017. New products appeared to replace them, but they are not identical.

LINKS

• BUILD A FULL-SPECTRUM LIGHT SOURCE

  Using special lights to produce a light source with all visible wavelengths

• Build a Spectroscope
• Other pages on LIGHT BULBS, SPECTRA, and HUMAN VISION
• Home