A process comprising (a) incorporating into an ink jet printing apparatus (1) a developing composition comprising a liquid vehicle and a color developer; (2) an oxidizing composition comprising a liquid vehicle and an oxidizing agent; (3) a coloring composition comprising a liquid vehicle and a dye coupler; and (4) a fixing composition comprising a liquid vehicle and a fixative; (b) causing droplets of the developing composition to be ejected in an imagewise pattern onto the substrate; (c) causing droplets of the oxidizing composition to be ejected in an imagewise pattern onto the substrate; (d) causing droplets of the coloring composition to be ejected in an imagewise pattern onto the substrate; and (e) causing droplets of the fixing composition to be ejected in an imagewise pattern onto the substrate; wherein the process results in at least some portions of the substrate bearing images comprising all four of the developing composition, the oxidizing composition, the coloring composition, and the fixing composition, said portions forming a printed image. Specific embodiments of the present invention are directed to the realization of continuous tone and gray scale in images by (1) control of the time at which color forming reactions are quenched by controlling the time period between deposition of the color forming liquids and deposition of the fixing liquid; (2) control of the extent of color forming reactions by limitation of the quantity of one of the color forming liquids; or (3) control of pixel size by drop placement control over the overlap areas of drops of color forming liquids.