Television image positioning and combining system

Apparatus for use with equipment producing a first television image, originating from a first television camera capable of being pointed in a variable direction so as to view differing parts of a foreground scene, said apparatus having the capability of producing a second television image originating from a single second television camera pointing in a fixed direction so as to view a background scene, said second television image moving coincident with, and corresponding to, horizontal motion of said first television image arising from change in the direction of viewing of said first television camera, in such manner that said first television image and said second television image may subsequently be combined, by the method of chroma-key, being known art, to form a combined image, said combined image than having the appearance of having been viewed by said first television camera, the positions of objects portrayed in said combined image undergoing displacement in accordance with the horizontal motions of said first television camera, said displacement applying equally to that part of said combined image deriving from said first television camera capable of being pointed a variable direction, and to that part of said combined image deriving from said second television image itself originating from said second television camera pointing in a fixed direction, comprising:

• a. means for sensing the direction of viewing of said first television camera, comprising a backing surface placed behind those parts of said foreground scene viewed by said first television camera, said backing surface having areas of a first color and an area of a second color different from said first color such as to cause said first television camera to generate two distinct and different values of its electrical output, the boundaries between said areas of said first color and said area of said second color being vertical lines, said boundaries performing the function of markers, the positions of said markers in the image formed by said first television camera being dependent on the direction of viewing of said first television camera,
• b. marker detector means for detecting transitions between said distinct and different values of said electrical output generated by said first television camera when viewing said first color and said second color, thereby detecting said markers,
• c. means for determining the positions within the image originating from said first television camera at which said transitions corresponding to said markers occur, and thereby producing indication of the direction of viewing of said first television camera,
• d. displacement generator means for generating displacement of the position of said second television image originating from said second television camera, consisting of means for accepting a first reference signal having synchronizing pulses in accordance with standard television practice;
• means for generating a second reference signal likewise having synchronizing pulses in accordance with standard television practice;
• and means for effecting a controllable variable time delay between the synchronizing pulses of said second reference signal and the synchronizing pulses of said first reference signal,
• e. means for supplying said second reference signal to said second television camera in such manner that the timing of the synchronizing pulses of said second reference signal controls the time at which said camera generates the electrical output signals corresponding to specific points in the scene viewed by said camera, and
• f. means for controlling said controllable variable time delay between the synchronizing pulses of said second reference signal and the synchronizing pulses of said first reference signal by an amount dependent on the direction of viewing of said first television camera derived from the detection of the positions of said markers in the output of said first television camera, said amount being such that the variation in said time delay so produced results in a variation in the timing of the video output signal derived from said second television camera equal to the variation in the timing of the occurrence of said markers in the video output signal of said first television camera;
• whereby a displacement in the timing of said markers resulting from a motion of said first television camera will cause an equal displacement in the timing of the video output signal from said second television camera, thus causing said output of said second television camera to follow in time, and thus in position when displayed on a television screen, any displacement of said markers resulting from motion of said first television camera.

Apparatus as recited in claim 22 wherein the image originating from said second television camera is compressed in the horizontal direction and wherein means are provided for effecting expansion in the horizontal direction of a selected part of said image, selection of said selected part being determined by said controllable variable time delay between said synchronizing pulses of said second reference signal and said synchronizing pulses of said first reference signal, whereby horizontal displacement of the content of said selected part of said image may be effected, said means for effecting expansion in the horizontal direction of a selected part of said image comprising:

• a. a source of first clock pulses,
• b. a source of second clock pulses having a lower frequency than said first clock pulses,
• c. first and second storage means each capable of storing a plurality of samples of a television signal supplied to its input and subsequently providing said samples at its output in the sequence of supplying to said input, the temporal separation between said samples supplied to said input being determined by said first clock pulses and the temporal separation between said samples provided at said output being determined by said second clock pulses,
• d. means for producing a control voltage alternating between a first value maintained for a time equal to the time of scanning of one horizontal television line and a second value maintained for a like time,
• e. means for selecting between said output of said first storage means and said output of said second storage means to form a selected output, and
• f. means for supplying samples of a television signal being that signal originating from said second television camera and said first clock pulses to said first storage means and supplying said second clock pulses to said second storage means and selecting said output of said second storage means to form said selected output when said control voltage has said first value;
• and for supplying said samples of said television signal originating from said second television camera and said first clock pulses to said second storage means and supplying said second clock pulses to said first storage means and selecting said output of said first storage means to form said selected output when said control voltage has said second value;
• whereby said samples will alternately be stored in, and retrieved from, each of said first and second storage means, and whereby, consequent upon said second clock pulses having a lower frequency than said first clock pulses, the temporal separation of said samples provided at said outputs of said first and second storage means, and consequently at said selected output, will be greater than the temporal separation of said samples of said signal originating from said second television camera supplied to said first storage means and to said second storage means, resulting in said selected output being expanded in time by comparison with said signal originating from said second television camera, such temporal expansion then resulting in a horizontal expansion of the image when subsequently displayed on standard television display equipment.

Apparatus for use with equipment producing a first television image, originating from a first television camera capable of being pointed in a variable direction so as to view differing parts of a foreground scene, said apparatus having the capability of producing a second television image originating from a single further television camera pointing in a fixed direction so as to view a background scene, the image originating from said further television camera being compressed in the horizontal direction and wherein means are provided for effecting expansion in the horizontal direction of a selected part of said image from said further television camera, said selected part of said image, having been expanded in the horizontal direction, forming said second television image, said second television image moving coincident with, and corresponding to, horizontal motion of said first television image arising from change in the direction of viewing of said first television camera, in such manner that said first television image and said second television image may subsequently by combined, by the method of chroma-key, being known art, to form a combined image, said combined image then having the appearance of having been viewed by said first television camera, the positions of objects portrayed in said combined image undergoing displacement in accordance with the horizontal motions of said first television camera, said displacement applying equally to that part of said combined image deriving from said first television camera capable of being pointed in a variable direction, and to that part of said combined image deriving from said second television image itself originating from said further television camera pointing in a fixed direction comprising:

• a. a backing surface placed behind those parts of said foreground scene viewed by said first television camera, said backing surface having areas of a first color and an area of a second color different from said first color such as to cause said first television camera to generate two distinct and different values of its electrical output, the boundaries between said areas of said first color and said area of said second color being vertical lines, said boundaries performing the function of markers the positions of said markers in the image formed by said first television camera being dependent on the direction of viewing of said first television camera,
• b. marker detector means for detecting transitions between said distinct and different values of said electrical output generated by said first television camera when viewing said first color and said second color thereby detecting said markers,
• c. means for determining the positions within the image originating from said first television camera at which said transitions corresponding to said markers occur, and thereby producing indication of the direction of viewing of said first television camera,
• d. displacement generator means for generating displacement of the position of said second television image originating from said further television camera, consisting of means for accepting a first reference signal having synchronizing pulses in accordance with standard television practice;
• means for generating a second reference signal likewise having synchronizing pulses in accordance with standard television practice;
• and means for effecting a controllable variable time delay between the synchronizing pulses of said second reference signal and said synchronizing pulses of said first reference signal,
• e. means for controlling said controllable variable time delay between the synchronizing pulses of said second reference signal and the synchronizing pulses of said first reference signal by an amount dependent on the direction of viewing of said first television camera derived from the detection of the positions of said markers in the output of said first television camera, and of such amplitude as to produce a variation in said time delay of magnitude proportional to any change in the times of occurrence of the signals produced by said markers in the output of said first television camera relative to previously obtaining times of occurrence of said signals produced by said markers, but having the opposite sense, a reduction in the amount of said time delay resulting from increase in the delay between the times of occurrence of said signals produced by said markers by comparison with previously obtaining times of occurrence of said signals produced by said markers,
• f. means for effecting expansion in the horizontal direction of a selected part of said image originating from said further television camera, including:
• a source of first clock pulses;
• a source of second clock pulses having a lower frequency than said first clock pulses;
• first and second storage means each capable of storing a plurality of samples of a television signal supplied to its input and subsequently providing said samples at its output in the sequence of supplying to said input, the temporal separation between said samples supplied to said input being determined by said first clock pulses and the temporal separation between said samples provided at said output being determined by said second clock pulses;
• means for selecting between said output of said first storage means and said output of said second storage means to form a selected output,
• g. means for producing a storage input control signal, being a pulse having a low value and a high value, the transition from said low value to said high value occurring during the time of said horizontal synchronizing pulses contained in said second reference signal, and the duration of said pulse being such as to permit a sufficient number of said first clock pulses to occur as to cause each of said first and second storage means, said first clock pulses being supplied thereto, to be filled to its storage capacity with said plurality of samples of a television signal supplied to its input,
• h. means for producing a storage output control signal alternating between a first value maintained for a time equal to the time between successive horizontal synchronizing pulses contained in said first reference signal, and a second value maintained for a like time, the transitions between said first value and said second value occurring during the time of said horizontal synchronizing pulses contained in said first reference signal, and
• i. means for supplying samples of a television signal being that signal originating from said further television camera and said first clock pulses to said first storage means when said storage input control signal has said high value and said storage output control signal has said first value and supplying said second clock pulses to said second storage means and selecting said output of said second storage means to form said selected output also when said storage output control signal has said first value;
• and for supplying said samples of said television signal originating from said further television camera and said first clock pulses to said second storage means when said storage input control signal has said high value and said storage output control signal has said second value and supplying said second clock pulses to said first storage means and selecting said output of said first storage means to form said selected output also when said storage output control signal has said second value;
• whereby said samples will alternately be stored in, and retrieved from, each of said first and second storage means, the times of commencement of storage being determined by the times of transition of said storage input control signal from said low value to said high value, said selected output forming the video signal capable of producing said second television image and whereby, consequent upon said second clock pulses having a lower frequency than said first clock pulses, the temporal separation of said samples provided at said outputs of said first and second storage means, and consequently at said selected output, will be greater than the temporal separation of said samples of said signal originating from said further television camera supplied to said first storage means and to said second storage means, resulting in said selected output being expanded in time by comparison with said signal originating from said further television camera, such temporal expansion then resulting in a horizontal expansion of the image when subsequently displayed on standard television display equipment, such that said second television image will have standard aspect ratio, the horizontal compression of the image originating from said further television camera being canceled by said horizontal expansion and whereby, consequent upon the timings of the transitions from said low value to said high value of said storage input control signal being dependent on the times of occurrence of said markers in the output of said first television camera, but in reversed sense, a retardation in the time of occurrence of said markers consequent upon a motion of said first television camera to the left will cause said storage input control signal to change state earlier thus commencing storage of the signal from said further television camera at an earlier time corresponding to the scanning of a part of the image of the background scene displaced to the left of that previously obtaining;
• thus a motion to the left of said first television camera will cause selection of a portion of said background scene to the left of that previously selected, and conversely motion to the right of said first television camera will cause selection of a portion of said background scene to the right of that previously selected, thus said second television image, being derived from the selected portion of the output of said further television camera, will move coincident with, and corresponding to, the motions of said first television image arising from motion of said first television camera.