Photo application for Ubuntu

[Geoffrey Combes]

Unless I have missed something in 14.04 LTS I can't find a Linux 
application that will reduce camera photo image size in  bulk (or 
automatically) rather than individually. I wish a size of 100 to 150kb 
for several uses (not only emails). At present I use GIMP one by one 
which is a slow process when dealing with a large number of photographs. 
Any suggestions please.
Geoffrey Combes