Identifying Color Defectiveness Using the FM Hue Test

The pattern of color defectiveness is identified using the FM Hue Test by bi-polarity, a clustering of maximum errors in two regions which are nearly opposite. The regions in which the errors are made can also be used to identify the type of color defectiveness.

Typical examples of patterns made by types of color-defective persons is given in the database of examples (Example.hdb) which accompanies this program.

The severity of the defect can be gauged by the extent of the 'bulge', a severe degree of defect showing clear bipolarity with high error scores; moderate cases show small 'bulges' and lower total error scores; mild cases with good color discrimination may show no 'bulge' and cannot be identified by this test.

The position of the mid-point of the errors in the pattern (the middle of the 'bulges' will identify the type of color defectiveness. The mid-point for indicating type of defect are best differentiated on the right-hand side of the pattern.

Protans

Protans have a mid-point between 62 and 70 as shown below.

Deutans

Deutans have a mid-point between 56 and 61 as shown below.

Tritans

Tritans have a mid-point between 46 and 52.

To aid diagnosis, confusion axes can be added to the polar plot by selecting Show confusion axes.

Diagnosis of color defectiveness should be made upon the average of at least two tests. The average of the mid-points of several tests will always fall within the ranges stated above. Some mildly defective individuals will be found whose discrimination or aptitude is so high that no amount of retesting will elicit a color-defective pattern.