DE2630948A1 - SWITCHING SIGNAL GENERATOR FOR TELEVISION SPECIAL EFFECTS - Google Patents

Description

The invention relates to a switching signal generator for television special effects, with two input circuits which supply signals U (X-X) and U (y-y), where U is a unit signal

C C

and where χ and y are numbers which are the coordinates related to the two axes of symmetry of the scanning grid of the image point scanned by a camera, while χ and y are adjustable parameters, and with a

C ^-7 C *

Generator circuit for generating switching signals that allow the generation of an outline, wholly or partially consists of a curve of the second degree, the generator circuit supplying horizontal frequency signals, the amplitude of which

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is a function of the second degree of the variable χ, and vertical frequency signals, whose amplitude is a function of the second degree of the variable y, as well as with an analog adding circuit for adding the horizontal frequency signals and the vertical frequency signals, and with a comparison circuit, its first Input receives the output signal of the analog adding circuit and a reference signal.

It is known that in television technology, for example in black-and-white television, in which video signals S and S print pictures A and B, sometimes a signal S, which appears on the screen of the receiver as a part of picture A, which fades into picture B with a certain outline that does not contain the relevant part. The effect achieved in this way is called trick fade-in. That Signal S can also cause part of image A, for example its right-hand part, next to part of the Image B is arranged, which is then its left part.

A switch is used for black and white television two signal inputs, which are the image signal S or the image—

(A)

signal S received, with an output that the signal S

supplies and with a control input that receives a switching signal, which depends on the dividing line between the two images.

In color television, the technology is more complex and depends on that

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used color television system. Finally, it is always necessary that a switching device is available that a Receives switching signal with two values "1" and "O", where this signal has one or the other of these two values, depending on whether the scanned pixel is on one side or the other of the dividing line.

If one considers the simple case of a circular line, the center of which is in the center of the scanning raster, then this reads Equation of this circle related to the horizontal x-axis and the vertical y-axis, both of which pass through the center of the Go through the scanning grid:

² , ² r ^ ² x + y = R

2 2
If the function Z = χ + y is formed by analog circuits, the signal representing the function Z must be combined with a

R representing the reference signal are compared, the

2 2 2 switching signal one of the values for χ + y <R and its other

2 2 2
has its value for χ + y> R.

If R changes by a ratio of 30, it must

2
Change the signal representing R by a ratio of 900.

Every inaccuracy and every instability in the implementation

2 of the function Z or in the reference signal R is expressed by deformed or unstable circles.

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-A-

In order to eliminate these defects, the current tendency is to provide digital circuits which operate at great speed work in real time or with permanent storage. This latter solution does not have the adaptability of the former, in particular with regard to changes in dimensions and position. One method and the other call for sizes to be handled 20 bits, the first in very short times on the order of 100 ns. In addition, require the Switching to these values means that numerous parallel switches or changeover switches are installed. The system is therefore expensive.

The aim of the invention is to provide a switching signal generator create, which in particular allows circular dividing lines, which have any radius, with a reference signal constant value using only analog circuits.

According to the invention, a switching signal generator of the type mentioned is characterized in that the generator circuit contains a first and a second analog multiplier circuit, which are fed by one or the other of the two input circuits and the signals U · X =

or U · Y = U .., where a and b are adjustable

Parameters are, as well as two operational circuits which are fed by one or the other of the two multiplying circuits and can output the signals U · > C or U * Y, and that the reference signal is the standard signal U.

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An embodiment of the invention is shown in the drawing and is described in more detail below. Show it:

1 shows the block diagram of an embodiment

of the switching signal generator according to the invention, and

FIGS. 2 to 4 show examples of dividing lines made with the aid of

of the switching signal generator of Fig. 1 can be obtained.

The mode of operation of the switching signal generator according to the invention

is based on the use of dimensionless small variables x-x y - y

C ¹ ^

χ ₌ Ξ_ γ ₌

away

where χ and y express the position of a pixel and where χ, y, a and b are variable parameters in analog circuits, where X, Y, X ² , Y ^{2 are represented} by the signals XU, YU, X ² U, Y ² U where U is an analog standard signal which is also used as a reference signal for the comparator or comparators, at least if the function to be compared is of the second order.

The generator of FIG. 1 contains several operational circuits and allows numerous dividing lines with a constant reference value to obtain that are straight or allow parallel axes of symmetry to the two scanning directions of the image.

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In Fig. 1, which is the block diagram of a switching signal generator shows according to the invention, two sawtooth generators 3 and 4 by means of pulses which are applied to their control inputs 1 and 2, respectively are horizontal frequency and vertical frequency synchronized with the cameras. The sawtooth generator 3 supplies for each active one Line duration a sawtooth xU, where U is a unit signal and where χ applies: χ = ρ _, where ρ is a constant,

T. an active line duration and t the middle of the active duration h h

of the line in question.

The generator 4 supplies one for each active partial image duration

t-t sawtooth y · U, where for y: y = rp · ^v , where

T the active partial image duration, t the middle of the active duration ν ν ₃

of the relevant part of the building and r the ratio - the height of the Image is too wide.

The generators 3 and 4 supply two algebraic subtraction circuits 5 and 6, the first of which is subtraction

χ. UU = UCx ~ ^x )> ^{with u} = x U c ^ er cc

and the second is subtraction

y.U-U '= U (y-y), with U' = y U cc 'cc

executes.

The subtraction circuits 5 and 6 supply two analog multiplier circuits 7 and 8, respectively, which generate the signals U ^c = UX

y ~ Vc

or U ——

are algebraic parameters.

= U · Y yeasts, where a and b are adjustable

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The multiplier circuit 7 is connected to the inputs of three operational circuits 9, 10 and 11, which r XU or ε _ο Ix IU or ε _ο X ² U

Yeasts, where the parameters ε, ε and ε each have the value

12 3

—1 and +1.

The operational circuits are connected to three of the four inputs of a switch 15 which has a single output and its fourth input is connected to ground.

The multiplier circuit 8 is connected to the inputs of three operational circuits 12, 13, 14, which ^{supply ε 'YU or ε'ο YI 1} - ¹ or ε * YU, the parameters ε'.,

c. · '3 1

i. and ε ' _{ο can} each assume the values +1 and -1. 2 3

These three operational circuits are connected to the inputs of a switch 16 which has the same structure as the Switch 15 has.

The outputs of switches 15 and 16 are with the two The inputs of an algebraic adding circuit 17 are connected, the output of which is connected to the first input of a comparator 18 is connected, while the second input of the comparator receives the unit voltage U. The comparator 18 inputs Signal with the digital value 1 when the signal applied to its first input is less than that to its second Input signal is applied, and returns when it is not

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is, a signal with the digital value O from.

When choosing a unit of length, the lengths expressed by the numbers χ and y become those on the two Axes of symmetry of the scanning grid related coordinates on the image of the image point scanned at time t.

A switching signal which results in a circle with the radius R and its center point as coordinates χ and y, (Fig. 2) has, can consequently at the output of the comparator 18 with the following settings of the generator can be obtained: in the subtracting circuits U = U χ, U * = Uy ,; in the multiplying circuits a = b = R; the outputs of switches 15 and 16 being connected to operational circuits 11 and 14, respectively.

In an analogous manner, one can elliptical or hyperbolic Lines are obtained with axes parallel to the coordinate axes, these lines in the case of a hyperbolic one Line can be limited by the scanning grid.

Fig. 3 shows a line consisting of a diamond ABCD, whose center coordinates are χ and y and the one has a vertical diagonal DB of length 2h and a horizontal diagonal CA of length 2d.

The four straight line segments AB, BC, CD, DA that delimit the rhombus can be expressed as follows:

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y - y ₂ = - 2Γ (χ - x ₂ ) + h, ι y - y ₂ 1 4 h, ι χ ■ -

y - y ₂ = 5- (χ - X ₂ ) + h, iy-y ₂ Kh, ι χ - χ ₂ ι

y - y ₂ = - ^ (χ - X ₂ ) - h, I y - y ₂ l <h, | x- X ₂ I

^y " ^y 2 ⁼ d ^(x " V ~ ^h '' ^y " ^y 2 ^! ^ ^h '1 ^x - ^x ₂ 1 ^ ^d

The four sides can get through the relationship at the same time

^ I 4- J —-I ⁼ ^ be defined what necessarily

requires that

y - y,

1 and

x-x

'2

Well.

The desired signal is thus obtained at the output of the

Comparator 18 by making X = 2 and Y = ^

a ^ h

as well as with the appropriate setting of the subtraction and multiplication parameters and with ε = ε * = 1 in the operating circuits 10 and 13 and in the alis of the / switches 15 and 16 are connected to the operation circuits 10 and 13, respectively will.

The generator of FIG. 1 apparently makes it possible to obtain any desired straight line which is parallel to the axes of symmetry or is inclined and does not pass through the center of the image, where the straight line χ = χ, with χ ^ O, at the exit

ο 3

of the comparator 18 is obtained, which - with the operational

circuit 9 is connected, with X = -, the operational

^X 3

circuit 9 is set to the value ε = 1 and the output of switch 16 is connected to ground.

For the straight line that goes through the center of the image

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go through it, for example y = px, with ρ positive, one has to

but either a comparator that Y = - and X = χ receives, use or, in order to avoid this additional comparator, of the equivalent equation y + 1 - px = 1 go out and

Y = y + 1

^{x =} öTör ^make '

using the operational circuits 9 and 12, with the circuit 12 set to ε '= 1, and the circuit 9 to ε. = -1 is set and the signal at the output of the comparator 18 is removed.

For some lines it can be advantageous if a second comparator 19 is present, which has the same structure as the comparator 18 and whose first input is connected directly to the output of the switch 16 alone, while its second input receives a variable signal kU , where 0 <k <1 applies. The output of the comparator 19 supplies the first input of an AND circuit 20, the second input of which is connected to the output of the comparator 18. The output of the AND circuit 20 forms a second output of the switching signal generator.

An application example of these additional circuit elements is given in FIG. 4, in which again in a larger Scale the diamond ABCD of Fig. 3 is shown. By

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Cutting the sides AB and BC of the rhombus with a horizontal EF and the sides CD and DA with a horizontal • GH you get a hexagonal line AEFCGH. The comparator 18, which is fed as before, · supplies a signal with the Digital value 1 for all points inside the diamond. Let 2m be the distance between the horizontals GH and EF. One uses the comparator 19 to a signal with the digital value 1 for I y - y I <m, that is for IYI <m / h (BD = 2h) and by adding the signal to the second input of the comparator 19 kU is applied, with k = m / h. The AND circuit 20 then supplies a switching signal which corresponds to a hexagonal outline. . "

It can be seen that a variable reference signal for the first degree variables χ and y does not have the disadvantage that it does for powers of χ and y.

Obviously, it is possible to add further analog circuit elements, further comparators and, to the switching signal generator Upstream comparators to add further digital circuit elements.

All circuit elements of the switching signal generator can be controlled either automatically or manually.

Parting lines which allow a gradual merging of the image A with the image B can be obtained by

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the conventional comparators with a sudden transition are replaced by devices whose output signal progressively changes from 0 to 1 (where the Output signal of the switching signal generator controlled switching device is then adapted to this case). The digital Circuit elements of the system are then replaced by analog multiplier circuits.

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Claims (7)

Patent claims: Switching signal generator for television special effects, with two Input circuits, the signals U (x - x) or U (y - y) C C supply, where U is a unit signal and where χ and y are numbers which correspond to the two axes of symmetry of the Represent the coordinates of the image point scanned by a camera, and where χ and y are a O O are adjustable parameters, and, for the generation of switching signals, which allow the generation of a contour that consists entirely or partially of a curve of the second degree, with a generator circuit that supplies horizontal frequency signals, the amplitude of which is a function of the second degree of the variable χ, and vertical frequency signals , the amplitude of which is a function of the second degree of the variable y, with an analog adding circuit which adds the horizontal frequency signals and the vertical frequency signals, and with a comparison circuit, the first input of which receives the output signal of the analog adding circuit and a reference signal, characterized in that the Gener at or circuit contains a first and a second analog multiplier circuit, which are supplied by one or the other of the two input circuits and deliver ^{the signals U · X − X} "* ^c or U. Y = U ^y " ^{y c} , where a and b are adjustable parameters, and two operational circuits ngen, which are supplied by one or the other of the two multiplier circuits and the signals U ♦ > C or U. Y can output, and that the reference signal is the standard signal U. 809884/0891 2. Switching signal generator according to claim 1, characterized in that that the operational circuit supplied by the first multiplier circuit optionally emits the signals Ux or -UX ^ can that the output of the second multiplying circuit 2! Operation circuit provided either the signals UY or -UY can output that the first multipHz circuit supplies two further operational circuits, one of which optionally - UX and the other - U IXI can output that the second multiplier circuit also supplies two further operational circuits which optionally output - UY and - I UY I can that each of the different from the first multiplier circuit provided operational circuits through a switch optionally with the first input of the algebraic adder circuit can be connected and that each of the operation circuits supplied by the second multiplying circuit through a further switch can be connected to the second input of the algebraic adding circuit. 3. Switching signal generator according to claim 2, characterized in that the output of one of the switches with the first input a further comparison circuit is connected, the two comparison circuits supplying a circuit element, which supplies a non-zero signal only when each of the comparison circuits has a non-zero signal Signal delivers. 4. Switching signal generator according to one of claims 1 to 3, characterized in that each of the comparison circuits is a comparator with a sudden transition. 609884/0891 5. Switching signal generator according to one of claims 1 to 3, characterized in that each of the comparison connections is a slow transition comparator. 6. switching signal generator according to claims 3 and 4, characterized in that that the circuit element is an AND circuit. 7. switching signal generator according to claims 3 and 5, characterized characterized in that the circuit element is an analog multiplier circuit. 609884/0891 Blank page