Questech Corporation

Hugh Kendal Littlejohn Questech Limited

Nicholas Barton

Robert Billing

Hugh K Littlejohn

Antony Richard Jones

Paul K Burgess

Hugh Kendal Littlejohn

In the processing of digital video signals there is provided in association with each signal an accompanying tally signal which provides an instantaneous identification of one or more signal sources from which the information contained in each pixel of a picture image has originated. The format of the tally signal may enable processing thereof to identify all signal sources contributing to a particular image area, to pixels of a mixed image or to any given field or frame of a video image signal. The signal may be encoded in the format of the digital chrominance signal component of a color picture signal and combined with a conventional key signal which is encoded in the format of a digital luminance signal so that the combined signal has the format of a color picture signal.

Providing an accurate tally indication of sources in use for output

Digital video effects with image mapping on to curved surface

Digital video effects apparatus for image transposition

A control signal synchronized to a digital video signal to be processed and defining the position of a rectilinear line (51,52,53,54) relatively to the image frame (50) is generated by providing an initial value corresponding to the perpendicular distance of the origin (0) of the scanning point of the video raster from the line (51,52,53,54) and incrementing or decrementing this value during movement of the scanning point in accordance with the rates of change of this distance in the horizontal and vertical directions. By logically combining the signals corresponding to a plurality of lines (52,52,53,54) a further signal is obtained which is 'true' when the scanning point is within a geometric figure defined by the lines. This signal can provide a 'key' signal controlling the display within the figure of image information to be combined with the video signal. Signals relating to four lines (52,52,53,54) forming a quadrilateral can provide coordinate signals for interrogation of a frame store containing image information to be transposed into the area defined by the quadrilateral figure.

Processing of video image signals

A video image processing system for generating so-called 'multi-freeze' digital video effects comprises a frame store (14) within which an image signal can be stored for application to a combining circuit (4) together with a background image signal (1) providing a background against which a trail of frozen images is to be displayed. The trail of images is derived by recycling images stored in the memory (14) through a further combining circuit (19) wherein the stored image is combined with incoming image signals applied to both combining means (4,19). Decay and patterning of the frozen images can be effected by circuits (24,25) for attenuating and profiling the key signals accompanying the image signals.

In a method of processing a video signal to provide digital video effects, an image signal is provided with an accompanying reference signal or Z-axis signal representative of the instantaneous distance of the scanning point of the video raster from an imaginary plane to be depicted as containing said information, taken in a direction perpendicular to the image screen. This reference signal may then be utilized to produce a variety of effects. For example a circuit for superimposing sets of image information to give the impression of an overlap in three dimensional space may comprise an order sorting circuit (1) having inputs (2,3,4) for sets of signals comprising picture information (P) a key signal (K) and a Z-axis signal (Z). At outputs (5,6,7) of the circuit the sets of signals are sorted into order of priority dependent on the magnitude of the Z-axis signal (Z). The picture signals (P) are mixed by multipliers (25,26,27) and a summer (28) to provide a composite picture signal in which the mixing of the components is determined by the multiplication factors of the multipliers (25,26,27). These factors are derived from the key signals having corresponding orders of priority, the key signals of lower order of priority being correspondingly attenuated by cascaded attenuators (12,13,14) coupled between lower order outputs of the sorting circuit (1) and a weighting circuit (11) for controlling the multipliers (25,26,27).

A storage and interpolation device for digital television pictures having a memory organized in `tiles` of memory elements (2). Sub-assemblies of tiles (2A, 2B, 2C, 2D) all have the same coordinate address in one coordinate direction and have outputs coupled to an interpolation filter (6) operative in that direction. Individual tiles (2A; 2B; 2C; 2D) of respective sub-assemblies (1A, 1B, 1C, 1D) all have the same coordinate address in the other coordinate direction and the outputs of the filters (6) of the sub-assemblies are connected to inputs of a further filter (9) operative in the other coordinate direction. By allocating pixel values of discrete image areas of the picture to respective sub-assemblies (1A, 1B, 1C, 1D) in the horizontal direction and to groups of tiles (2A, 2B, 2C, 2D) in the vertical direction, interpolation can be effected by addressing all tiles simultaneously to produce a corresponding output from the filter 9.

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Wokingham, United Kingdom

Nicholas Barton