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We present concurrency control techniques used in Collaborative IMage Editing Systems (CIMES). CIMES adopts a replicated architecture: shared pattern images are replicated at the each participant site; so image operations are performed at local sites immediately and then propagated to remote sites. An image operation transformation algorithm is proposed to resolve the image editing conflicting caused by multi-user collaborative editing and to maintain the consistency of shared image. Then, an image undo/redo algorithm is presented to support group undo in the same editing sessions. Finally, a distributed locking mechanism is used as a concurrency control tool in some collaborative phase to prohibition of shared updating to a region. All of these are realized in CIMES.