Tennis ball fuzziness: assessing textile surface roughness using digital imaging

Wear plays an important role in the game of tennis as it affects both ball performance and player perceived ball quality. Visual appearance can be used in ball differentiation, but has so far been limited to subjective assessments used to estimate ball wear and performance characteristics. A metric for ball surface condition will allow performance and perception data from varied testing set-ups to be objectively compared and analysed. A versatile new method of assessing surface roughness using digital imaging has been developed to allow the quantitative assessment of tennis ball condition. This metric allows manufacturers and researchers to predict ball performance and player perception from worn ball samples, developing acceptable wear limits. In the successful implementation of this metric, several key factors, including lighting, image thresholding, algorithm implementation and camera specifications, were identified to aid future alternative implementations.