Patent GB-1444411-A (GB)
Title: image modification of a recorded scene
IPC: H04N5/84
Filed: 1973-08-02
Abstract: 1444411 Television ASSOCIATION OF MOTION PICTURE & TELEVISION PRODUCERS Inc 2 Aug 1973 36783/73 Heading H4F In an arrangement for modifying a visual image of a scene recorded on a plurality of frames of a recording medium such as a photographic film (or recorded in the form of video signals on a magnetic tape, disc or other medium) electronic information representative of the image elements in a frame and of the addresses of such elements in the frame are derived and stored in a computer and from such information a visual display of at least some of the frame is produced, the stored information representative of image elements surrounding a part of the display to be modified is then selected (e.g. by light-pen means), the computer is programmed to select corresponding information representative of image elements surrounding corresponding parts of successively adjacent frames and to modify the so surrounded parts in a chosen manner and the modified frames are then recorded as a modified visual image. The modifications may comprise altering the definition, resulution, hue or colour purity or contrast, colouring an initially white image, eliminating grain, dirt, random scratches, noise or selected parts of the image, e.g. wrinkles from a human face and the insertion of desired features such as shadows particularly in connection with composite image arrangements involving separately photographed foreground and background scenes. Fig. 1, shows an embodiment in which the images are recorded on colour photographic film 20 a frame 21 of which is scanned by a known flying-spot scanner arrangement 10 to provide corresponding Red, Green and Blue component video signals. The latter, after shaping and amplifying, as required, in amplifiers 50-52 are digitized in A/D converters 53- 55 and supplied to a video distributer 60 together with corresponding digital addresses from a clock driven digital address generator 34 which, via a D/A converter provides the scan of the flying-spot scanner tube 12, of a monitor display tube 90 and of a display tube 102 in a film recording device 100. The signals supplied to the distributer 60, (which may be displayed directly on tube 90 in order to monitor the action of the flying-spot scanner 10), are supplied to a computer 70 and from the latter, under the control of a logic circuit 82, supplied to tube 90 via a D/A converter 96 and a circuit 134 which may be operated to produce a "blinking" effect. Initially, (without the "blinking" effect operative), the display is inspected by an operator who may, by adjustment of controls 93, 94, expand and reposition, as required, a selected part of the display which it is intended to modify, e.g. the portion within rectangle 88 (Fig. 2). Such an expanded portion then allows detailed examination of individual image elements (which may appear, e.g. as shown in Fig. 3) and the operator, having selected a piratcular horizontal scan line, such as Y 0 , passing through the area to be modified, determines, by means of a light-pen 120, approximate addresses (indicated on tube 90 by "blinking") such as X L , X R  (Fig. 4) for the positions where the scan line crosses the left and the right hand boundaries, respectively of the area considered. These addresses are stored in the computer memory and the computer is then programmed by means of a logic circuit 82 to generate a pair of left and right hand addresses which accurately represent the effective boundaries in accordance with a specified functional relationship of the video values. Such relationship is dependent on the nature of the object and of the background (from which it is to be distinguished) and the type of modification to be carried out and the new addresses generated in this manner may differ slightly from the lightpen selected values X L , X R  as shown by X OL , X OR . The latter values are then stored in the computer memory preferably after verification by display on monitor tube 90 and the computer is now programmed to generate equivalent addresses for all scan lines crossing the boundaries of the image concerned in the frame considered and for the required number of successively adjacent frames, such addresses also being stored, preferably after verification in the computer memory. The computer is then programmed to effect the required modications of the surrounded image, the modified signals are stored in the computer memory and then recorded frame-by-frame on photographic film 106. The operation of the arrangement for the elimination of film scratches is described with rereference to "flow" diagrams Figs. 8A, 8B and 8C (none shown).