The Japanese quail lays eggs with colourful and patterned shells which make the eggshell colour difficult to classify. In this study, the method of measuring colour of patchy eggs using image analyses and its power to discriminate among individual variation were established. Estimated repeatability for egg colour and proportion of patterned areas was high (>0.58), suggesting intermedíate or high heritability of eggshell colour characteristics. Three components have been identified as significant in discriminant function analysis. These three components explained 91.4% of the total variance in egg colour characteristics. In cluster analysis, 78.3% of the eggs that were collected from 15 females were correctly classified. This study indicates that eggshell colour characteristics can be reliably studied by image analyses and that this method can provide a unified character list for future examinations and interpretations of quail egg characteristics.