JPH02143694A - Picture signal conversion circuit - Google Patents

Abstract

PURPOSE:To attain the conversion of a video signal in the state of a digital signal and to hardly receive noise effect by using a conversion list in a memory so as to convert a luminance color difference video signal into an RGB video signal. CONSTITUTION:Inputted luminance color difference video signals Y,I,Q are converted into digital signals Y,I,Q by A/D converters 100,101,102 respectively and fed to address inputs A0 - A3, A4 - A7, A8 - A11 of a memory 103. RGB video signals R,G,B corresponding to the signals Y,I,Q being the result of digital coding are written in addresses Q,I,Y of the memory 103 in advance. Thus, the values R,G,B are read at outputs D0 - D3, D4 - D7, D8 - D11 of the memory 103. The signals are converted into video signals R,G,B by D/A converters 104,105,106.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an image signal conversion circuit, and particularly to a digitally encoded nine RGB video signal or a luminance/chrominance video signal into a luminance/color difference video signal or an RGB video signal, respectively. The present invention relates to an image signal conversion circuit that performs conversion.

[Conventional technology]

Generally, RGB video signals R, G, B and luminance/color difference signal Y
, I, and Q, the following equation holds true.

R=0.62Q+0.96 I-)-Y...
・・・・・・・・・(1) G=-0,64Q-0,28
I+Y ・・・・・・・・・・・・(2) B=1.
70Q-1, lQI+Y ・・・・・・・・・・・・
(3) Conventionally, as an image signal conversion circuit that converts a luminance/chrominance video signal into an RGB video signal according to the above formula, 1 is used, for example, "Elementary TV Textbook" 44 by Takuji Mashima, published by Ohmsha.
The IJ circuit described on page 9 is known.

FIG. 3 is a circuit block diagram showing a specific example of a matrix circuit according to the prior art.

According to FIG. 3, the matrix circuit in the conventional example includes amplification/phase inversion circuits 300 and 301 and resistors 302 and 31.
Contains 3.

In FIG. 3, resistor 302. The resistance values of ~313 are R1 and ~R12, respectively, and the amplification/phase inversion circuit 300
Let α and β be the positive and negative gains of , and let r and δ be the positive and negative gains of the amplification/phase inversion circuit.

In FIG. 3, the color difference signal Q is transmitted to the amplification/phase inversion circuit 300.
and output as color difference signals -αQ and +βQ. Similarly, the color difference signal engineer uses the amplification/phase inversion circuit 30.
1 and output as color difference signals -γI and +δ.

Color difference signals obtained in this way -αQ, +βQ, -γ
+δI is connected to the resistors 302 to 31 along with the brightness signal Y.
3 is added to the resistor network constituted by .

As a result, RGB video signals 几, G, B expressed by the following formula are obtained as outputs of this resistor network.

Therefore, in equations (4) to (6), the gains α, β, r, δ and the resistance value R1°~
If R12 is determined, equations (4) and (6) become (1) and (
The matrix circuit shown in FIG. 3 is the same as the formula 3), and the matrix circuit shown in FIG.

G, BIC conversion is possible.

[Problem to be solved by the invention]

The conventional image signal conversion circuit described above converts the luminance/color difference signals Y, 1. Since we are performing addition and subtraction of Q,
The disadvantage is that it is easily affected by noise.

[Means to solve the problem]

The image signal conversion circuit of the present invention converts first image information represented by a KGB video signal or a luminance/color difference video signal into second image information represented by a brightness/color difference video signal or an RGB video signal, respectively. The circuit is characterized by comprising a memory in which a value obtained by digitally encoding second image information corresponding to the first image information is written at an address indicated by the digitally encoded first image information. shall be.

〔Example〕

Next, the present invention will be explained with reference to FIGS. 1 and 2.

FIG. 1 is a block diagram showing an embodiment of the image signal conversion circuit of the present invention, in which luminance/color difference video signals Y and I are processed.

An example is shown in which Q and RGB video signals R, G, and B are each expressed as 4-bit digital codes.

According to FIG. 1, this embodiment has input luminance and color difference video signals Y, 1, . A-D converter with Q added (hereinafter referred to as A
-D) 100, 101, 102 and A-Dloo, 10
1,102 outputs are respectively addressed to A0 to A3.
Memory 103 added to A4~A, , A, ~AlH
and data output from memory 103.

~D3. DA converters (hereinafter referred to as DA) 104, 1 whose inputs are connected to D4 to D, , D, -D1□, respectively.
05°106.

FIG. 2 is a diagram showing the address space of the memory in FIG. 1.

According to FIG. 2, the brightness of the memory 103 shown in FIG.
Color difference video signal Y, 1. The addresses (Q), (I), and (Y) obtained by digitally encoding Q into 4 bits each contain RGB video signals (L, B, and G) corresponding to the luminance/color difference video signals Y, I, and Q, respectively. Values (R) and (B) obtained by 4-bit digital encoding.

(G) is written in advance.

In this embodiment, input luminance/color difference video signals Y, I,
Q is 4 by A-Dloo, 101, 102 respectively
Bit digital signals (Y), (I), (Q
) is converted to These digital signals (Y), (I).

(Q) is the address A0 to A of the memory 103.

They are added to A4~AT and A@~A1H, respectively. As mentioned above, the address (Q) (I
) α) are the values (R), (B), (G
) is written in advance, this is memory 1.
03 output Do~Ds, D4~Dr, 2)s
-Dll has this value (R) (B) (G)
is read out. Furthermore, this digitally encoded 9R,
GB video signal (R), (B).

(G) is converted into an analog RGB video signal, B, and GK by D-A 104, 105, and 106, respectively.

Note that in this embodiment, the luminance/color difference video signals are RGB
Although an example of converting to a video signal has been shown, converting an RGB video signal to a luminance/color difference video signal can be performed in exactly the same manner.

〔Effect of the invention〕

As explained above, the present invention provides luminance/color difference video signals Y,
By converting I and Q into RGB video signals R, G, and B by reading a conversion table written in memory in advance, it is possible to convert the video signal in the digital signal state, thereby reducing noise. This has the effect of making you less susceptible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the image signal conversion circuit of the present invention, FIG. 2 is a diagram showing the address space of the memory in FIG. 1, and FIG. 3 is a specific example of a matrix circuit according to the prior art. It is a circuit block diagram showing. 100, ~102...A-D converter (A-D), 10
3...Memory, 104. ~106...D-A converter (DA), 300, 301-...Amplification/phase inversion circuit, 302°313...Resistor. $1 Zuizumi ZN Agent Patent Attorney Susumu Uchihara

Claims (1)

[Claims] A circuit that converts first image information represented by an RGB video signal or a luminance/color difference video signal into second image information represented by a brightness/color difference video signal or an RGB video signal, and which is digitally encoded. An image signal conversion circuit comprising: a memory in which a value obtained by digitally encoding second image information corresponding to the first image information is written at an address indicated by the first image information.