Automatic Stockigt Sizing Test Using an Automatic Recognition Principle of Colour Expression

The St ckigt sizing test, which is readily affected by the bias of individual testers recognizing red colouration, has been modified to improve its reliability and reproducibility. A novel testing system for the Stockigt sizing test with an automatic procedure for the recognition of red colouration was developed using an automatic liquid dispenser and a stepping motor. The analysis program uses a hue value to recognize the point of time at which red colouration appears, rather than RGB (Red, Green and Blue) values, as these do not correlate well with human perception of colour. Hue proved to be more sensitive in terms of recognizing the red colouration of a droplet than the other two HSV factors - colour saturation and colour value (brightness). During the test, the program records the time taken for a droplet on a specimen to reach a specific hue value. Unlike the conventional test, the automatic test was able to obtain a reliable and reproducible sizing measurement with only minor errors.