  We present an extraction of the valence transversity parton distributions
based on an analysis of pion-pair production in deep-inelastic scattering off
transversely polarized targets. Recently released data for proton and deuteron
targets at HERMES and COMPASS permit a flavor separation of valence
transversities. The present extraction is performed in the framework of
collinear factorization, where dihadron fragmentation functions are involved.
The latter are taken from a previous analysis of electron-positron annihilation
measurements.
