Questech Corporation

Hugh Kendal Littlejohn Questech Limited

Robert Billing

Nicholas Barton

Hugh K Littlejohn

Paul K Burgess

A digital video effects apparatus is arranged to generate a digital video effect by interpolating the values of parameters governing the effect, according to a given function, between time points corresponding to selected frames of a video signal and at which the parameters are fixed at selected values. The apparatus is organised in such a manner that the values of parameters are stored in exclusive timelines enabling the time points at which the parameter values are fixed to be adjusted without reference to other parameters governing the same video effect.

Digital video effects, apparatus and method

A digital divider for forming the quotient (Q) of two numbers (A,B) includes means providing values (Q+1, Q-1) of the quotient with possible rounding errors added to or subtracted therefrom. Selector switching means is arranged to select one of the values (Q, Q+1, Q-1) under the control of a logic circuit operating according to the following rules: ##EQU1##

Accurate digital divider

Digital video effects with image mapping on to curved surface

Digital video effects apparatus for image transposition

Recording and editing of moving television pictures

Error-correction of stored television signals

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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Crowthorne, United Kingdom

Robert Billing