JPS60122992A - Digital color encoder - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides direct color information from digital color information signals.
The present invention relates to a digital color encoder that forms a composite color video signal such as a TSC signal.

Generally, an NTSC composite color video signal is given by the following equation.

E (t)=Y+ 0.493'(B-Y) sin ω
t +0.877 (R-Y) cos ωt ・ ・ ・ +11 Here, Y is a luminance signal, B-Y is a blue color difference signal, R-Y
is a red color difference signal. These are given by the following equations from the color information signals R, G, and B, respectively.

Y= 0.299R+ 0.587G+ 0.114B
...(2) B −Y = −0,299R−0,587G + 0
．． 886B・・・(3) RY=0.701R-0,587G-0,114B
...(4) In formula (1), ω(=2πf)−2πX 3.57
9545M1lz, and f is the frequency of the color subcarrier (=3.579545MHz).

In a conventional digital color encoder, the digitized color information signals R and GSB are a luminance signal Y and a color difference signal I corresponding to R-Y and B-Y.

After converting the signal into a Q signal, a composite color video signal is formed using an analog balanced modulator or the like.

This method requires individual signal sources, has a low degree of freedom in color image processing regarding digitization processing and its arithmetic processing, has a complicated circuit configuration, and is difficult to implement due to cost considerations.

An object of the present invention is to directly form a composite color video signal from coefficients obtained in advance through predetermined sampling and digitized color information signals consisting of three primary colors or other primary colors.

In this invention, a color video signal is sampled at a sampling frequency that is an integral multiple of the color subcarrier, and a coefficient obtained for each phase that is equal to this integral multiple and a digitized color information signal are sampled at a predetermined sampling frequency. A color video signal for each phase is formed by multiplication based on , and a composite color video signal is formed by arithmetic processing of this color video signal.

That is, in the above formula +11, the sampling frequency is 10.738635 which is an integer multiple of the color subcarrier, for example, 3 times
A color video signal is sampled at MHz, and the formula (
By substituting 2), (3), and (4), the following color video signals for each phase are obtained.

E(0π/3ω) = 0.91378R+ 0.07
220G +0.01402B...(5) E(2π/3ω) =-0,13605R+ 0.59
378G+ 0.54227B...(6) E(4π/3ω) = 0.11927R+ 1.09
502G-〇, 21429B...(7) In this invention, a color video signal is sampled at a sampling frequency that is an integral multiple of the color subcarrier, and the coefficients obtained for each phase that are equal to this integral multiple and the digitized The obtained information signals R, G, and B are multiplied by the multiplication means, and these equations (5)
, (6) and (7), R, G, and B for each phase and their coefficients are sampled by sampling the color video signal at a sampling frequency that is an integral multiple of the color subcarrier, and for each phase that is equal to this integral multiple. The obtained coefficients are multiplied to form a color video signal for each phase, and this color video signal is processed to form a composite color video signal for obtaining a real image.

In this case, the color information signal is not limited to the three primary color signals R, G, and B that have been digitized in advance, and color information such as cyan, magenta, yellow, etc. can be used.

The present invention will be described below with reference to embodiments shown in the drawings.

FIG. 1 shows an embodiment of the digital color encoder of the present invention, and this embodiment shows a case where a desired color image is formed using a computer in a television receiver for broadcast reception (hereinafter referred to as a TV receiver). ing.

In FIG. 1, the main storage device 2 is a continuous memory (
RO'M) and rewriteable memory (RAM)
It consists of A color video display program is written in the ROM, and calculation data is stored in the RAM.

This main storage device 2 includes a central processing unit (hereinafter referred to as cp).
The CPU 4 reads out an arithmetic processing program and desired data from the main storage device 2 in response to instructions, and executes arithmetic processing.

This CPU 4 is connected to a video memory (hereinafter referred to as V-RAM) 10 via a data bus 6 and an address bus 8.
．． 12.14 are connected, each V-RAMIO112,1
4 is a sea fence control circuit (Sequential
An addressing signal is applied from the controller 16.

In the V-RAMIOs 112 and 14, color information consisting of digitized R, G, and H signals is individually stored for each hue, and the contents of these stored data are as follows:
It is formed by the PU4 or updated by the CPU4.

The Sea Fence control circuit 16 generates the NTSC synchronization signal and the color burst generation timing, and also generates the addressing signal of V-RAMI 0112.14, so that R, G, Each signal of B is not read out.

R1GSB read from V-RAMIO112, 14
The signals are individually applied to multipliers 18, 20, 22 installed corresponding to V-RAMIO 112, 14, and each multiplier 18, 20, 22 has a coefficient memory (hereinafter referred to as coefficient ROM).
) 24.26, and is multiplied by a predetermined coefficient read from the wing.

Each coefficient ROM 24, 26, 28 stores the coefficients of each phase silver related to R, G, and B in equations (5), (6), and (7), and the phase signals S+ (0', ), 32 (120'
), 33 (240°), a predetermined coefficient is generated. Each coefficient converts the color video signal into a color subcarrier (
f: 3.57'9545M)Iz) (7) Integer multiple (7) 1 line (This is a numerical value obtained for each phase (angular period) and color information equal to this integer multiple by sampling at IJ1 wave number. This coefficient value is calculated in advance and stored in the coefficient ROM24.26.
．． 28 shall be stored in memory.

Further, the coefficient ROM 30 stores color burst signals, and the phase signals SL (0''), 32 (120
°) and S3 (240''), a color burst signal is generated by a timing signal from the sea fence control circuit 16.

Color burst signals generated in these coefficient ROM 30,
The multiplication outputs of each multiplier 18.2o, 22 and the synchronization signal from the Sea Fence control circuit 16 are added to an adder 32 as an arithmetic means. This adder 32 converts the multiplication output of the multipliers 18.2o and 22 into the equation (5),
R and G in (6) and (7).

For each term of B, an addition process is performed to form a composite color video signal for obtaining a real image, and a color burst signal and a synchronization signal are added to the addition result.

This addition output constitutes an NTSC digital composite color video signal, which is applied to a digital/analog signal converter (hereinafter referred to as DAC) 34 to be converted into an analog signal, and then amplified by an amplifier 36 to be used for TV reception. ta3
added to B.

According to such a configuration, the predetermined color information signals R, G, and B calculated by the CPU 4 are sent to the V-RAMI O.

12.14, and the color information signal is read out in accordance with the display timing of the TV reception vIA 38 by an address signal generated by the sea fence control circuit 16.

This color information signal is expressed by the above equations (5), (6) and (7).
This corresponds to each of R, , G, and H.

On the other hand, the coefficient ROM24.26.28 contains the phase signal S1.
(0°), 5t (120°), and 5i (240°) are added, and the coefficients corresponding to each phase signal, that is, the coefficients of each phase silver are read out.

The coefficients of each phase silver and the color information signals R, G, and B are as follows:
Based on the predetermined sampling frequency, the multiplier 18.20.22
is calculated for each phase silver, thereby forming a color video signal for each phase silver.

FIG. 2A shows the sampled frequency signal and FIGS. 2B, C and D show the phase signals S+%32 and S3. Each phase signal 31% 32 and S3 is a three-phase signal with the same frequency as the color subcarrier and whose phases are shifted from each other by 120°, and whose high level interval is set equal to three times the sampling period. ing. Therefore, this phase signal 5
When the coefficients read out at ISS2 and S3 are multiplied by the color information signal in sequence, the arithmetic processing is synchronized with the sampling frequency.

The coefficient R
The color burst signal and synchronization signal read from OM 30 are added in adder 32 to form a digital composite color video signal. In this case, the synchronization signal is
Then, the color burst signal has the timing shown in FIG. 3B, and is actually the result of inserting 8 to 10 Hz of the color subcarrier into the back porch of the synchronization signal.

This digital composite color video signal is converted into N
After being converted into a TSC composite color video signal and amplified by an amplifier 36, it can be output to a TV receiver 38 as an actual image.

In this example, the sampling frequency is 3 of the color subcarriers.
I set it to double (= 10.738635MFIz), but
It can be set to any integer multiple of the color subcarrier.

A specific example of color image formation will be described below. Set the sampling frequency to 3 times the color subcarrier (=10.74M1l
z), dividing 10.74MHz by the horizontal scanning frequency of the TV receiver 38, 15.73426 K11z, yields 10.74Mh/15.73426 MHz =
682.5...(81, and the result is not an integer. Therefore, with a clock signal of 3 times the sampling frequency of the color subcarrier, that is, 10.74 MIIz, it forms the length of the horizontal synchronization period IH. However, in order to form accurate NTSC color images, the phase of the color burst signal also changes for each horizontal scanning line. must not.

Color subcarrier 3.58 MHz horizontal scanning frequency 15
．． Divide by 73426 K11z, 3.58 MIIZ/ 15.73426 KHz =
227.5 (91), the length of the IH is not an integral multiple of the wavelength of the color burst signal, and a remainder of half a wavelength occurs.

Therefore, the normal color burst signal shown in FIG. 4A becomes a color burst signal as shown in FIG. 4B, and this color burst has a phase shift of 180° for each IH.

According to formulas (7) and (8), 10.738635 MI
Equation (1) is sampled at Iz, and the length of IH is set to 63.
6 (=1/15.73426 K11z), it becomes impossible to form an NTSC color image.

Therefore, if we change the phase of equation (1) by 180°, E(t)
=Y+ 0.493(B-Y) sin (ωt-
π) + 0.877(RY) cos (act-
π) That is, E (t) = Y O, 493 (BY) sin a
ct −π) −0,877(RY) cos ωt
...It becomes an alpha groan.

From this, it can be seen that in order to form an accurate NTSC color video signal, sampling calculations should be performed alternately every l line scans using the formula +l) and the formula (Im).

In FIG. 5, A is the composite color video signal in this case,
B is a composite color video signal, C is a 10.74 MHz clock signal, and A+ and Az are horizontal synchronization signals. The clock signal C is operated so as to be extended by the amount that does not result in an integer ratio as a result of the above calculation, as shown in Go.

Such an operation is necessary when the sampling frequency is set to three times the color subcarrier, but is unnecessary when the sampling frequency is set to four times the color subcarrier.

As explained above, according to the present invention, a color video signal is sampled at a sampling frequency that is an integer multiple of the color subcarrier, and the coefficients obtained for each phase that are equal to this integer multiple and digitized color information are obtained. A color video signal for each phase is formed by multiplying the signal based on a predetermined sampling frequency, and a composite color video signal for obtaining a real image is formed by processing this color video signal. , compared to the conventional method in which a color video signal is formed after converting to a color difference signal, the circuit configuration is improved because a real image is obtained from the digitized color information signal and predetermined coefficients to form a composite color video signal. Along with the simplification of color images, the degree of freedom of color images will be expanded, and realization will become easier in terms of cost.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the digital color encoder of the present invention, Fig. 2 is an explanatory diagram showing a sampling frequency signal and a phase signal, and Fig. 3 shows the generation timing of a color burst signal with respect to a horizontal synchronization signal. An explanatory diagram, FIG. 4 is an explanatory diagram showing a phase shift of a color burst signal,
FIG. 5 is an explanatory diagram showing a composite color video signal, a composite color video signal, and a clock signal according to the present invention. 10.12.14...-V-RAM, 18.20°22
... Multiplier, 24.26.2B, 30... Coefficient RO
M, 32...Adder as calculation means. Procedural amendment 1. Indication of the case 1982 Patent Application No. 231017 2, Name of the invention Digital Color Encoder 3, Person making the amendment Relationship to the case Patent Applicant Address 10-1 Nakazawa-cho, Hamamatsu City, Shizuoka Prefecture Name (40)
7) Nippon Gakki Mfg. Co., Ltd. Representative: Hiroshi Kawakami 4, Agent address: 2nd floor, Ogikubo Kangyo Building, 3-2-2 Amanuma, Suginami-ku, Tokyo (167) 6. Scope of claims of the specification subject to amendment Column 7, Contents of the amendment (11 The claims column of the specification is amended as shown in the attached sheet. (2) r Hz J on page 10, line 3 of the specification is amended to "cycle". (3) rKHzJ on page 10, line 15 of the specification is rk
Correct to HzJ. (4) rKHzJ on page 11, line 6 of the specification to rkH
Correct to zJ. (5) rKHzJ on page 11, line 7 of the specification is r k
llz Correct to J. (6) "By formulas (7) and (8)" on page 11, line 14 of the specification is amended to "by formulas (8) and (9)." (7) Figure 1 of the drawings shall be amended as shown in the attached sheet. Above 2, the claimed color video signal is sampled at a sampling frequency that is an integral multiple of the color sub-transmission - L6? a multiplier for forming a color video signal for each phase by multiplying 6ht: equal to i'e by a digitized color information signal based on a predetermined sampling frequency; 1. A digital color encoder comprising a calculation means for forming a composite color video signal by performing calculation processing on the obtained color 7 video signals for each phase.

Claims (1)

[Claims] The color video signal is sampled at a sampling frequency that is an integer multiple of the color subcarrier, and the coefficient obtained for each phase that is equal to this integer multiple is multiplied by the digitized color information signal based on the predetermined sampling frequency. A multiplication means for forming a color video signal for each phase by doing this, and a calculation means for forming a composite color video signal by processing the color video signal for each phase obtained by the multiplication means. A digital color encoder characterized by: