Colour blindness test
Follow the link below to the online Ishihara colour blindness test.
The original card version of this test (by Dr Shinobu Ishihara) was designed to be carried out in a room adequately lit by daylight.
The presence of direct sunlight or artificial light may produce some discrepancy in the results because of some alteration in the appearance of shades of colour.
This electronic version may also produce some discrepancies as the images have been optimised for web-based delivery and with a monitor resolution of 800x600 and 256 colour display or greater.