The invention generally relates to systems and methods for color correcting video picture signals and for detecting scene changes during color correction operations. More particularly, the invention pertains to improved systems and methods for increasing the quality and speed of color correction operations by enhancing the ability of color correction equipment to determine when a new scene begins. This patent application describes improvements upon the color correction systems and methods disclosed in U.S. Pat. No. 4,096,523 (the "Rainbow" patent); No. 4,223,343 (the "Anamorphic" patent); No. 4,410,908 (the "Luminance" patent); No. 4,679,067; and No. 4,694,329; as well as those disclosed in copending, commonly owned U.S. Pat. Appl. Ser. No. 807,815, entitled "Editing System and Method"; Ser. No. 851,164, entitled "Color Correction System and Method"; Ser. No. 942,901, entitled "Color Correction System and Method"; Ser. No. 943,218, entitled "Color Correction System and Method"; and Ser. No. 943,298, entitled "Color Correction System and Method." The disclosures of these patents and patent applications are hereby incorporated herein by reference.
There is a continuing need to improve the efficiency, speed, and quality of the color correction of video picture signals, especially in film-to-tape and tape-to-tape transfers, and particularly in scene-by-scene color correction. For instance, there is a need for equipment that more accurately senses new scenes in a motion picture film or a videotape that is being color corrected. Furthermore, there is a need to prevent the physical degradation of motion picture film and videotape caused by scratching due to the back-and-forth movement necessary to find the beginning of a scene. Moreover, there is a need to reduce the time an operator spends hunting for the start of a scene.
An accurate scene-change detector is especially important when a videotape is being color corrected, since the image may change at the video field rate of 60 hertz. By contrast, when a motion picture film is being color corrected, the image may change at the frame rate of 24 hertz. Hence, finding the start of a new scene on a videotape may be very difficult and time-consuming to accomplish manually inasmuch as more images appear during a given period than with a film.
A scene-change detector or analyzer is advantageously used with a color corrector, as indicated in an article entitled "The Pre-Programming of Film-Scanner Controls," by D. J. M. Kitson, A. B. Palmer, R. H. Spencer, J. R. Sanders, and M. Weston, which was published in E.B.U. Review, No. 134, August 1972, on pages 156-162, and an article entitled "Preprogrammed and Automatic Color Correction for Telecine," by D. J. M. Kitson, J. R. Sanders, R. H. Spencer, and D. T. Wright, which was published in the Journal of the SMPTE, Volume 83, August 1974, on pages 633-639. There is a need for improvement of scene-change detectors or analyzers.