the invention herein provides a method and apparatus for the continuous automatic duplication of original film on a much more economical electrophotographic film . the original film is represented by the strip 10 and comprises for example , 35 millimeter silver halide film having a plurality of frames of different images along its length . usually such images will be positives in that they can be projected for viewing in order to utilize the information contained thereon . as examples , the film may be cinematographic film , microfilm or a sequence of photographic stills . the duplicate film is preferably the type of electrophotographic film disclosed in the copending application and comprising a plastic film substrate having a sputtered coating of cadmium sulfide bonded thereto with an ohmic layer sandwiched between the cadmium sulfide coating and the substrate . as explained in the copending application , the coating is a high speed , high gain , high resolution electrostatic material which is capable of unusual charge acceptance and is of variable sensitivity . it can be exposed with speeds comparable to those at which conventional photographic film can be exposed and it is considerably more economical than silver halide film because there is no silver in the film . additionally , it is durable and abrasion resistant , is unaffected by moisture and most chemicals and has remarkable archival qualities since it is unaffected by fungus or long periods of storage in various atmospheres . the duplicate film is shown in the figure as the strip 12 . the supply reel for the photographic film 10 is shown at 14 and its take - up reel at 16 . the supply reel for the electrophotographic film 12 is shown at 18 and its take - up reel is shown at 20 . the film speed drives and controls are not shown since these may be conventional in order to assure that the translative speed of both films at the exposure station 22 is the same . various guide and tension rollers for controlling the movement of the film strips 10 and 12 are shown at 24 and their operation and construction are too well - known to require further description . the direction of movement of the respective film strips is indicated by the arrows . the film strips move in opposite directions . the original film strip 10 comes off the supply reel 14 , passes alongside of a photocell 26 which continuously responds to the background density of the framed images . a lamp 28 may be stationed below the film strip 10 to direct a beam of light through the image and onto the photocell 26 . the emulsion on the surface of the film strip 10 preferably faces downward as at 10 &# 39 ;. from the photocell 26 and lamp 28 ( which together may be termed a background density measuring station 30 ) the film strip 10 passes to the projection station 32 which is located identically along the length of the both film strips 10 and 12 as the exposure station 22 . here there is an optical slit 34 which receives light from the lamp 36 projected through an optical system 38 , part of which is above the film strip 10 and part of which may be below the strip 10 . the film strip 10 is then wound up on the take - up reel 16 . looking at the electrophotographic film strip 12 , its photoconductive coating is disposed on its upper surface 12 &# 39 ;, that is , facing the emulsion surface 10 &# 39 ;. just prior to passing a slit 40 which guides the beam 44 from the projector 38 , the photoconductive surface 12 &# 39 ; is charged by the charging means 42 . this may be a corona producing device of any suitable construction . the photoconductive surface of the film strip 12 is charged in darkness and as is the case with electrostatic members , it assumes a charge on its photoconductive coating or below the same which is capable of being discharged by photons represented by a light pattern . such pattern is provided by the beam of light 44 passing through the slit 40 ( the apparatus being otherwise in complete darkness ) and as a result , since the two film strips 10 and 12 are moving at the same speed , albeit in opposite directions the images from the photographic film 10 are laid down in a continuous flow fashion onto the electrophotographic film 12 as latent images . immediately after passing the exposure station 22 , the latent images pass into a toning station 46 at which the surface 12 &# 39 ; of the film strip 12 receives a flood of liquid toner from dispenser 48 supplied from any suitable source . immediately after the flooding of the surface by liquid toner the excess may be removed by a suction device 50 . the liquid toner may be of such type that the solvent evaporates quickly and the particles which do not adhere to the charged film fall or are brushed or are blown off the film . in any event , the function performed at the station 46 is toning . the film then passes to a fixing station 52 at which point a heat lamp 54 fuses the toner to the film surface 12 &# 39 ;. the invention contemplates a type of toner which will adhere to the film without being fused by heat . the completed duplicate film strip 12 is then wound up on the take - up reel 20 . although not illustrated , means may be provided at the payout side of the reel 18 fully to discharge the photoconductive coating of the film 12 . this could be an intense light , for example , for wiping off static charge picked up inadvertently . it is known that the higher the surface potential to which an electrostatic member is charged , the greater the affinity for toner particles adhering thereto . this principle is used in the invention to achieve automatic image enhancement in the duplication of the images from the original to the electrophotographic film . thus , the signal from the photocell 26 at the station 30 is applied by the line 56 to one lower terminal 58 of a differential amplifier 60 whose upper terminal 62 derives a signal from a reference source 64 . the reference signal source 64 is constructed to provide a fixed signal that has been adjusted by simple experimentation to represent a standard of image background density which provides the optimum of acuity for the duplicated image . thus , signal source 64 may be a simple d . c . voltage source and a potentiometer calibrated in terms of background density . bright images will produce more light in the beam 44 than dim images . the bright images will require less toning because they will result in greater discharge of the surface than the dim images . since the toning supply is continuous and the time of toning is fixed , the control may be exerted by means of the surface charge , that is , by raising and lowering the charge potential . a dark image passing little light should call for a higher charging potential than a bright image passing more light so that in the case of the dark image more toner will be caused to adhere . accordingly , it is a simple matter to adjust the reference signal source 64 so that when the photocell 26 measures a background density which is average there will be no output from the differential amplifier 60 but when the background density is too bright there will be a decrease in the charge voltage ; likewise when the background density is too dark there will be an increase in charge voltage . the output of the differential amplifier 60 appears at 66 and is applied to the input of a charge voltage control circuit 68 controlling the power supply 70 to the charging means 42 . the output from the control 68 passes to the charge means 42 by way of the line 72 which may have a delay circuit 74 to compensate for the time that it takes for the film location point of measurement of background intensity at station 30 to reach the charging station 42 . the control of toning by varying the charge voltage will provide the optimum contrast for the duplicated film 12 and in effect could provide higher quality , in some instances more information than retrievable from the original film by simple duplication . it might be mentioned that the duplication proceeds according to the invention with the film strips 10 and 12 spaced apart as of necessity . this is in contrast with contact printing done in conventional duplicating processes . as a result there is better copying with greater depth of field ; no scratching or transfer of dust ; no flutter of film at high speed . also prior processes had to be conducted in complete darkness , but in the invention herein only the charging , exposing , toning and fixing stations need be in darkness . variations are capable of being made without departing from the spirit or scope of the invention as defined in the appended claims .