The measurement of digital images has become a common technique used for conformation and biomechanics research. In an experimental study, animal scientists from Brazil examined the accuracy of a method for measuring conformation utilizing an image measurement JAVA software program called Image J. Eight markers were attached to 34 Quarter Horses and nine angular and linear measurements were obtained by physically measuring the horse (reference measurements). These measurements were compared with those obtained using the software to measure a digitized lateral photograph (estimated measurements) adjusted for scale.
The image analysis software was considered to have great accuracy with a nearly perfect (0.9999) correlation to reference values. Longer measurements (body length) and some larger angles (pelvis-femur angle) showed the most variation. Overall, the authors concluded that digital image analysis using ImageJ is an accurate and precise method for obtaining body measurements of the horse. In addition to having low variance, the measuring procedures using the digital images were less bothersome and stressful for the horses compared with obtaining physical measurements.
— Freitag GP et al. JEVS 2021;in press