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Cambridge Color Blind Test

Color Blindness Test

Must Know Details About Cambridge Color Blind Test

[Author : Admin | Date : 6, April 2023 | Reading time : 6 min]

Feeling like you're not seeing colors as clearly as they should? Have you ever been told that something has different shades but all look the same to you? Then you could be color blind and don't know. Then you need to do color blindness test. For example, they know that the leaves on trees are green, so they think the color they see is "green".

This vision problem does not usually cause you to see things in shades of gray. That's weird. Most color blind people have trouble distinguishing some colors. You may not be able to distinguish between red, green, or blue. and yellow. Ophthalmologists have many ways to check the condition.

The most common tests use blackboards or colored charts. There are several factors that can cause vision loss and blindness. These can be happens due to hereditary influence, environmental or unintentional. To understand how blindness can affect a person, it is necessary to first define blindness. Color blindness, also known as color blindness (CVD), is the inability to see color differences or variations.

This syndrome can make it difficult to select ripe produce, select clothing, and follow traffic lights. Color blindness can make certain academic tasks more difficult.

However, most concerns are minor, and color-blind people learn adjustments and coping methods on their own. People with total color blindness (achromatopsia) may feel uncomfortable in bright situations and have poor visual acuity.

Who Does the Tests?

If you notice a serious change in how you see color, call an ophthalmologist. That's a doctor who’s trained in eye care and vision. Your symptoms could be a warning sign of something more serious, so it's a good idea to get them checked out. You should also tell your regular doctor if you think you’re having trouble seeing colors.

In some schools, nurses test children for color problems. Color blindness runs in families. If you have relatives with the condition, it’s important to get tested.

What Are the Different Kinds of Tests?

  1. Ishihara color blind test
  2. Kids color blind test
  3. Cambridge color blind test
  4. Anomaloscope color blind test
  5. Farnsworth lantern test
  6. Farnsworth-Munsell 100 hue test.

Here we are going to discuss about Cambridge color blind test in details.

Cambridge color blind test

This is a lot like the Ishihara test, except that you look at a computer screen. You’ll try to find a “C” shape that’s a different color than the background. It pops up randomly. When you see it, you press one of four keys.

This examination is quite similar to the Ishihara Test, with the exception that you see a computer screen. You will look for a "C" shape that is a distinct color from the background. It appears at random. When it appears, press one of the four keys on the screen. 

This test allows the researcher to quantify the progression or remission of the disease over time. Many drug addicts have color vision impairments. The pharmacologist will be able to use the test to keep an eye on the short-term and long-term bad effects of blindness.

Examining chromatic sensitivity along the color confusion lines, the test determines discrimination ellipses in color-deficient individuals. People with even the slightest color vision problem tend to see generated ellipses oriented and bigger. 

How to perform the Cambridge Test

The Cambridge test is simple to perform for both colorblind and non-blind individuals. On a background that doesn't have any color, this test uses a familiar Landolt C stimulus, which is defined by the two test colors that need to be distinguished.

The target's first use of vibrant, bold colors helps establish the test-taker's dependability in identifying the direction of the C-shape shown. Then, based on the user's performance, the computer modifies the color quality (chromacity) between the target and the backdrop. This test comes in both longer and shorter iterations.

For those with low vision, there is another variation of the Cambridge test with four plates, but these plates only have one color and no dots or targets. One of the plates is a distinct color, and the other three are neutral, grayish hues. The test-taker must recognize the circle with the specified color.

The Cambridge Colour Test for ViSaGe provides a rapid means of screening subjects for colour vision deficiencies. It can also be used to examine in more detail the changes in colour discrimination that occur as a result of congenital or acquired conditions.

The price indicated below is for the Cambridge Colour Test software only for use with an existing ViSaGe system and CRT monitor. For a complete ready to run system including the Cambridge Colour Test plus Low Vision Colour Test, Visual Acuity, and Spatial & Temporal Contrast Sensitivity Function.


ViSaGe MKII Stimulus Generator

ViSaGe makes it simple to present calibrated visual stimuli on CRT, LCD, DLP and OLED based displays with precision timing, and provides a robust and reliable mechanism to synchronise the stimulus presentation with external data collection equipment, including button boxes or eye trackers, motion trackers, electrophysiological amplifiers, and MRI scanners. It is the ideal choice for cognitive, psychophysical, and neurophysiological investigations of vision and the brain. 

ViSaGe advantage: 

Real-time driver for Windows guarantees frame-synchronous presentations even at 100Hz+ frame rates

14bit colour and luminance control with integrated support for gamma correction and colour calibration

Dedicated PCI Express framestore to buffer sequences of precalculated images Integrated digital I/O interface for controlling third-party equipment like electrophysiological amplifiers. A choice of MATLAB programming for total flexibility, or use pre-programmed experimental paradigms.

Proven: ViSaGe is the Gold Standard visual stimulus generator and is based on 25 years of development. It has been used in literally thousands of experiments worldwide and is cited in the leading peer-reviewed journals.

Compatible: ViSaGe will integrate easily into your laboratory setup and can be combined seamlessly with our other products and peripherals to provide a customised solution to your research needs.

Precise: ViSaGe offers accurate frame-based timing, and precise luminance and colour control. 

Easy: The CRS Toolbox for MATLAB is our recommended software tool for programming the ViSaGe. Its interactive script language is very easy to learn, and our high level routines extend MATLAB and make it easy to control the ViSaGe and other CRS equipment in powerful and familiar ways.

The Visual Psychophysics Engine provides a suite of pre-programmed experimental paradigms for ViSaGe. The simple and intuitive interfaces are user friendly, and sufficiently flexible for most research applications.

The Cambridge Colour Test provides a rapid means of screening subjects for colour vision deficiencies, or examining changes in colour discrimination.

Why do I need ViSaGe?

Getting from that brilliant insight to the crucial experiment can be the hardest part of any research project. The choices for visual stimulus generation can be bewildering, but false starts waste your time and money.

Computer graphics seem the obvious solution, but it's not always that simple. Most systems are really designed for games: they are difficult for novices to program and unsupported by the manufacturer. Often their dynamic range is limited, with inadequate contrast and colour control for experimental applications, and timing is unpredictable.

Investigate the limits of colour discrimination

The Cambridge Colour Test provides a rapid means of screening subjects for colour vision deficiencies; but it also can be used to examine in more detail the changes in colour discrimination that occur as a result of congenital or acquired conditions.

It allows the investigator to monitor quantitatively over time the progression or remission of disease. Many drugs affect colour vision and the pharmacologist will find the test well suited to monitoring the short-term or long-term course of such side-effects.

The test determines discrimination ellipses in colour deficient subjects by probing chromatic sensitivity along the colour confusion lines. Ellipses measured in individuals with even slightly anomalous colour vision are characteristically orientated and enlarged (see references).

Easy to use

The procedure is easy to use for both the investigator and the subject. It uses the familiar Landolt C stimulus, defined by the two test colours that are to be discriminated, on an achromatic background.

The Cambridge Colour test uses the proven concept of introducing spatial and luminance noise into the stimulus, which is composed of grouped circles randomly varying in diameter and having no spatial structure. The Landolt C is therefore defined by chromaticity alone, ensuring that the subject's responses are not due to luminance or spatial cues in the stimulus, and thus avoiding the necessity for a preliminary procedure to find isoluminance for the test colours.

The test is conceptually very simple to explain to the subject, who responds to the orientation of the Landolt C using the 4-button infra-red response box. The chromaticity of the components of the C is varied along the protan, deutan and tritan lines (or other chromatic axes if desired) using a standard descending psychophysical staircase procedure.

The Importance of Stimulus Resolution

The 8 bit output resolution of conventional computer graphics systems offer too coarse a resolution for measuring the limits of human colour discrimination. The stimuli are produced by ViSaGe, which provides 14 bit colour and luminance control and is calibrated using a ColorCAL. Cambridge Colour Test can therefore provide a finely graded measurement of discrimination and allows small changes to be monitored over time or in different experimental conditions.


The Cambridge Colour Test is an established method and has been widely used for both clinical and basic research including an extensive normative data set. (see references).


Results are saved in ASCII format and presented graphically as discrimination ellipses in CIELUV or CIE(x,y) colour space. The results shown are typical of a subject with normal colour vision; in deficient subjects the discrimination ellipses are significantly extended in the protan, deutan or tritan chromaticity directions.


The Cambridge Color Test employs plates with colored dots, similar to the Ishihara test, but uses a C-shape in a different color from the background, combining the ideas of the Ishihara test with modern technology. The test-taker must click on one of four keys to indicate the orientation of the C-shape, or "target," which appears arbitrarily in one of four orientations.

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Color Blindness Test
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