Lithographic printing plates can be obtained by contacting infrared radiation-imaged negative-working lithographic printing plate precursors with a processing solution having a pH less than 9 and comprising a UV photoinitiator. After this processing, the lithographic printing plate is floodwise exposed with UV radiation. Providing a UV-photoinitiator in the processing solution followed by UV exposure can increase imaging sensitivity and printing plate run-length, and reduce print background.