This invention relates to a photosensitive element for use as a flexographic printing plate and a process for preparing the plate from the element. The photosensitive element has at least one photopolymerizable elastomeric layer that comprises a binder, a monomer, a photoinitiator, an onium salt, and a leuco dye. Upon exposure to actinic radiation, the onium salt and leuco dye react resulting in a change of color in polymerized portions of the photopolymerizable layer. The color change provides enhanced image color contrast in the photosensitive element.