add missing png.
add missing png.

aabadie/medInria-public,rdebroiz/medInria-public,aabadie/medInria-public,rdebroiz/medInria-public,rdebroiz/medInria-public,aabadie/medInria-public,NicolasSchnitzler/medInria-public,NicolasSchnitzler/medInria-public,NicolasSchnitzler/medInria-public