Stork Colorproofing B.v.

John T Alston

Josef Matkan

An image reversal process for the production of electrophotographic color proofs from negative separation films where the photoconductive recording member is reusable and the proofs are produced on printing stock paper and which very closely match the appearance of the printed sheet. The process of the invention comprises, exposing a photoconductor that is charged to a first polarity through a color separation negative film which may be in contact therewith, developing the unexposed areas on the photoconductor with opposite polarity background toner to form background deposits thereon in areas corresponding to the opaque non-image or background areas on the negative, subjecting the photoconductor and the background deposits thereon to corona discharge of said first polarity to charge the photoconductor in the areas free of said background deposits, that is, in areas corresponding to the transparent image areas on the negative, removing charges of said first polarity from the background deposits, developing the image area on the photoconductor with opposite polarity color toner, and transferring the thus formed color toner deposits to a receptor such as printing stock paper. The process can be repeated for each additional color separation negative film to transfer the additional specific color developed image in proper registry where a proper toner for the specific color image will be used.

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Myrtle Bank, Australia

John T Alston