Color blindness or color vision deficiency is the inability to differentiate between colors. The most common type of color deficiency is Red-green color blindness. There are many tests to detect color blindness but the Ishihara test is the most popular one. This test consists of 38 Ishihara plates having numbers or shapes out of dots on the center of the plate with different colors than the dots surrounding them. People with color deficiency find it difficult to identify the numbers shown on these plates. If you also have difficulty differentiating colors you can take this Ishihara color test to detect color deficiency.