  Schlieren flow visualizations of transverse oscillations of jets submitted to
an acoustic perturbation are analyzed in this paper. The aim is to estimate the
shape and the position of the median line of the jet. Two methods for image
processing are proposed, based on complementary approaches : inter image and
intra image analysis. Synthesized images of an oscillating jet are used to
validate each method and compare their performances in the case of noisy
pictures. Illustrations are then shown on real laminar and turbulent jets. The
results obtained using both methods are very close, showing their reliability.
Applications investigated in this paper are focused on the estimation of the
convection velocity of perturbations along the jet, and the influence of the
Reynolds number and of the channel geometry upstream the jet formation.
