Abstract:
A method and system for color correcting and completing answerprints in preparation for making final copies of motion pictures for distribution. A light system is provided in which colors of the light projected through a film toward a viewing screen can be individually and incrementally adjusted as desired for use by a color “Timer” who is an individual that selects color corrections on a scene-by-scene basis until a suitable look is achieved. The Timer does this in real time while watching the film scene projected on the screen. The color adjustments are stored and subsequently used to control a motion picture film printer in printing a next version of scenes of the film.

Description:
The present invention relates to scene to scene color correction of motion picture film preparatory to making final copies, called release prints, to be distributed to theaters and the like. More particularly, it relates to a new method and system for color correcting and completing answerprints in a more efficient and faster manner. 
     BACKGROUND OF THE INVENTION 
     Significant advances have been made over the years in the production of motion picture films. Today, scenes are printed on motion picture film, although some systems record on videotape. Still, the preferred method is film. A typical motion picture is made up of many daily film shots or scenes referred to as “dailies,” from which workprints are made. These workprints are used to make answerprints which in turn are used during the color correction of scenes in the film. The numerous corrected scenes are ultimately assembled together for production of the final positive film prints called release prints for distribution to theaters and the like. 
     Of the various artistic aspects in the production of a motion picture film is color correction. Movie scenes are taken under different lighting conditions, on different days, in different locations, and the like. As a result, the colors may vary substantially from scene to scene which is undesirable in a final print. Additionally, some producers and directors may desire a given “mood” to a scene or scenes, such as darker, lighter, warmer (e.g. add red), more blue, less magenta and so on. Color correction currently is performed mainly in two ways. 
     The first way is frequently referred to as an answerprint timing process which involves individuals referred to as color “Timers” who work with customers to determine the look they would like for each and every scene of a film. The process continues until all of the cuts, transitions, sequences from film reel to film reel appear to have been shot simultaneously, uninterrupted and seamless throughout. The current hardware available for this process usually includes a pair of timing stations which comprise film strip projectors whereby the Timer can roll through a film and stop and evaluate each scene. Currently, one must rely on the experience and the “eye” of the color Timer to determine the amount of correction each scene needs. The various correction values are stored and used to control a film printer in making a new film print for further review and analysis by the Timer. The accuracy of their assessment, unfortunately, is not realized until the next time the negative is printed and developed using the values the Timer has chosen. This whole process usually needs to be repeated several times until all of the scenes in the film have the look that the Timer and the customer desire. As will be appreciated, each of the iterations uses time and resources as well as places additional wear and tear on the film negative. 
     Another approach to color correction involves recording the scenes in the video domain and viewing the scenes un a color video monitor. As the scenes are viewed, the electronics of the video system can be adjusted to vary the color according to the desires of the Timer. The color changes made are stored electronically and then used to control the film printer in printing a new copy also referred to as an answerprint. This print then is viewed to determine if the color corrections have been made satisfactorily, and to again enable color adjustments in the video domain, followed by the production of another print for further evaluation. Although this system and process allows adjustment and real time viewing of color changes, the actual results on film are still unknown until another new film print has been made and viewed because of the differences in color rendition via film versus video on a color monitor. 
     FIG. 1 is a flow chart which generally illustrates prior methods of answerprint timing wherein the Timer is the “operator,” and is generally the same for either of the prior two methods discussed above 
     SUMMARY OF THE INVENTION 
     The system and method of the present invention involve a new approach to color correction. Basically, the film, referred to as an answerprint, is projected onto a conventional viewing screen through the use of a light system in which the colors of the light projected through the film toward the screen can be individually and incrementally adjusted by the Timer. If the look is not as the Timer desires, color, density and the like can be changed and the results seen immediately on the screen. The adjustments are stored electronically and used to make the next film print. This process is repeated for each of the scenes in a roll of film. As a result, the film printing process is instantly simulated and the Timer can see the results of the changes and therefore a great deal of time and money can be saved. This system and method are significantly different from the current answerprint timing process which does not allow the Timer to view the color changes in real time and also differs from the video system which, although it allows changes to be seen in real time in the video domain, the Timer still does not know what the color changes in the film will look like until a new print is made. It will be apparent that seeing the actual projected changes via controlled light through the film onto a viewer&#39;s screen is better and more accurate than viewing changes on a video monitor. 
     In accordance with an embodiment of the present invention, a color correcting “vane house” and lamp house of the type used in a standard optical film printer are used as the light source for projecting the film onto a screen. This type of vane house comprises narrowband dichroic light filters, and the entire visible light spectrum is broken down into three separate color paths, of red, green and blue. This is what is done in conventional film printing and the resulting colored light is merely used to print unexposed film, not project any film image. However, the vane house includes light valves within each color path, and these valves are used to control the amount of each individual color being projected to the viewing screen. This “color corrected” light of each of the colors is recombined and used to project the answerprint film onto the screen for scene-by-scene and/or frame-by-frame evaluation by the Timer. 
     An exemplary vane house has three light valves, each of which has a range of seventy-six steps called “light points” to control the amount of each color. The vanes are controlled electronically, and typically a position command to each of these light valves is a twelve bit digital signal. These commands can be provided from an associated computer or other suitable control system. Accordingly, as the Timer, who is considered to be the color expert, enters the value desired to be used to correct each of the three colors for any given scene, that information will now go into the present system and be stored, as well as control the light projected through the film so that the Timer can see in real time what those correction values look like. Then, if the look is not as the Timer desires the value can be changed in real time and the result seen on the screen immediately. Once the Timer is satisfied with the result, the data corresponding to the changes of each light valve, and consequently the resulting color changes, for each scene is electronically saved, and this data is used to control printing of the next print. As noted earlier, this process is repeated for each of the scenes in a roll of film, and from roll to roll. Thus, by instantly simulating the printing process, a great deal of time and money can be saved in completing the color correction of a motion picture film. 
     In the typical vane house, the light valves are mechanical “bam door” type devices and the vanes thereof are driven by servo motors. The concepts of the present invention also contemplate the use of other light and color controlling devices such as other optical, electronic and/or semiconductor light valves. 
     Accordingly, it is an object of the present invention to provide an improved real time answerprint timing system. 
     Another object of the present invention is to provide an improved real time answerprint timing method. 
     These and other objects and features of the present invention will become better understood through a consideration of the following description taken in conjunction with the drawings in which: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a flow chart illustrating the existing or prior art method of answerprint timing and illustrates the various steps in the process of completing film color correction. 
     FIG. 2 illustrates an exemplary answerprint timing system according to the present invention. 
     FIG. 3 is a flow chart illustrating the present new method of real time answerprint timing. 
     FIG. 4 is a block diagram of an answerprint printing control system. 
     FIG. 5 is a flowchart illustrating control of the light valves of an answerprint printer. 
    
    
     DETAILED DESCRIPTION 
     Turning now to the drawings and first to FIG. 2, an exemplary real time answerprint timing system is illustrated and comprises a film strip projector  10 , a color control unit such as an optical printer vane house  12 , and a lamp house  14 . The system further includes an interface computer  16 , film position encoder  18 , and main answerprint computer terminal  20  with a file server  21  or other suitable storage system. The lamp house  14  provides a source of white light, and the vane house  12  includes optics for modifying the color of the light from the lamp house which is ultimately projected through film  22  via the projector  10  to a screen  24 . The lamp house has a cooling fan  27 . The interface computer receives light valve color correction data usually input by the Timer for a current scene, and the position encoder  18  provides information about film  22  position to keep track of frames and views. The interface computer  16  provides this information to the computer  20  which, in tum, uses this information in later controlling a standard film printer in controlling color in printing a new answerprint as will be discussed later. 
     The vane house  12  and lamp house  14  are conventional in an optical film printer. The lamp house  14  includes a high wattage lamp  26 , typically a Tungsten Halogen 1200 watt lamp, but may be replaced with a more powerful lamp source if the system is to be used with a larger screen  24 . The vane house  12  is used to modify the color of the light source, and the optics, filters and light valves thereof are conventional to produce a color controlled light beam  28  for the film projector  10 . The optics and filters preferably are narrowband dichroic light filters. 
     The film projector  10  is a conventional projector with a standard lens  30 , film gate and optics; however, the usual lamp section of the projector  10  is removed and the vane house  12  and lamp house  14  are used instead. The light beam  28  from the vane house  12  is projected through the film  22 , and the resulting images are projected via the projection optics  30  onto the projection screen  24 . The film  22  is fed from a reel  34  and taken up by a take-up reel  36 . 
     The film  22  passes over the position encoder  18  so as to provide frame-by-frame position data  80  to the computer  20 . In this way, the system is able to keep track of each frame and scene which is important because color changes may be made frame-by-frame or scene-by-scene and, accordingly, the frame and/or scene information along with the color values need to be sensed and provided to the answerprint computer  20  for ultimate control of film printing. Thus, the interface computer  16  is used to receive the light valve data (color correction) values for each frame and/or scene and to provide that information from the encoder  18 , along with the film position information, to the main answerprint computer  20 . The data from the answerprint computer  20  is used to control the conventional film printer (not shown) in printing a new answerprint with the selected color changes via a network or other data transfer  87 . 
     Turning again to the vane house  12 , the same includes a number of narrowband dichroic light filters  40 ,  41 ,  42  and  43 , front surface mirrors  46  and  47 , and three optical light valve assemblies  50 ,  51  and  52  which can include light vanes to vary the level of light passed thereby or other forms of light valves as noted earlier. As is known, light beam  60  from the lamp house  14  is first directed to dichroic filter  40  which (1) reflects red light  62  and (2) passes light in the cyan spectrum at  64  to a second dichroic filter  41  which (1) reflects green light  66  and (2) passes blue light  68 . The red light beam  62  is reflected by the mirror  46  as beam  70  to a red dichroic filter  42 . The green light beam  66  is reflected by filter  42  and combined with the red light  70  to provide a yellow beam  72  to the dichroic filter  43 . The blue light beam  68  is reflected by front surface mirror  47  to filter  43 , resulting in the color controlled output beam  28  made up of various values of red, green and blue light, and this resulting light beam is passed through the film gate  31 , film  22 , and projection lens  30  to project the film images onto the viewing screen  24 . 
     The light valves  50 ,  51  and  52  individually and incrementally control the amount of each of the colored beams passed thereby. The respective settings as directed by data paths  81  through  83  to the respective valves  50 ,  51  and  52  are sent via signal path  86  to the main answerprint computer  20  and stored therein. These stored values are stored later to set up the light valves in the film printer (not shown) along with film position data  80  from the encoder  18  via the interface  16  so as to property set the colors for each scene and/or each frame as the next answerprint is made by the film printer. 
     FIG. 3 is a flow chart which specifically illustrates the operations performed by the Timer (identified as “operator” in FIG.  3 ). At  90  the Timer (or operator) loads film on the projector  10  (FIG.  2 ). At  91  the operator enters the appropriate job number on the computer terminal  20 , and then proceeds at  94  to view the current scene as projected on the screen  24  via the projector at  10  (FIG.  2 ), and the Timer can view any appropriate data on the monitor of the answerprint computer terminal  20  at  96 . If correction is needed, the operator makes the appropriate adjustments at  97  and the correction value data is stored as indicated at  98  in the server  21  and the process continues at  100  or if no correction is needed, the Timer proceeds directly at  100  to the next scene, and that scene is viewed at  94  and the correction sequence  96 - 98  is repeated if it is not the end of the job. If there is no further scene and it is the end of the job  103 , then the process proceeds at  105  to make a new answerprint with the new light values as is described below (FIGS.  4 - 5 ). 
     Turning now to FIGS. 4 and 5, these illustrate the respective film printing system under control of the answerprint computer terminal  20  and the steps in the process of the operator inputting the stored correction values for controlling the film printer light values. Thus, FIG. 4 shows the computer  20  which has received, and stored in file server  21 , all of the light valve data values for each frame and/or each scene from the interface  16 , as well as the film position information from the encoder  18 . This information is now provided at  110  to an interface unit  112  which powers and controls the printer light valves  114  of a conventional motion picture film printer. As seen in the flow chart of FIG. 5 the answerprint printer operator inputs current scene and correction values at  120 , which is the data which has already been stored, and this data is converted at  122 , to a 12 bit digital number as is conventional in a film printer to control the conventional film printer light valves  114 . It is desirable that the viewing light control system  12 , such as a conventional vane house, be the same as that used for printing so that the light values are consistent from viewing to printing. 
     While embodiments of the present invention have been shown and described, various modifications may be made without departing from the scope of the present invention, and all such modifications and equivalents are intended to be covered.