JPS59211394A - Digital color encoder - Google Patents

Abstract

PURPOSE:To form a composite color video signal by processing digitally a component data such as three primary color video data. CONSTITUTION:Primary color data R, G, B are applied from input terminals 1, 2, 3 and taken as address inputs to ROMs 11, 12, 13. A data converting table representing the corresponding between the address input and the output data is stored to each ROM. A luminance data Y is applied to a delay circuit 21 for time matching and color difference data R-Y and B-Y are applied to low pass filters 22 and 23 of digital constitution. An output of delay circuits 21, 22, 23 is applied to an ROM30 as an address input. Four data converting tables 31, 32, 33 and 34 are stored in the ROM30. The digital composite color video data is read at the output of the ROM30. The data is D/A-converted and applied to an adder 38 to which a burst signal and a synchronizing signal are applied, then the result is outputted via a low pass filter 41.

Description

Detailed Description of the Invention [Industrial Application Field J] The present invention relates to a digital color encoder that forms a composite color video signal by digitally processing component data such as video data of three primary colors. I'm concerned.

"Background technology and its problems" Video camera capture and image output signals and display data output from microcomputers are R and G.

B (three primary color signals). R,G.

In order to display the above color signal on an NTSC monitor receiver that does not have a B input terminal, it is necessary to convert it to an NTSC system composite signal (composite color video signal). Conventional analog color encoders use matrix circuits to encode R, G, and R.G.

A luminance signal Y and color difference signals U and V are formed from the B signal, the subcarrier is orthogonally two-phase modulated by this color difference signal to form a carrier color signal, and the carrier color signal is added to the luminance signal Y. It was designed to generate a composite signal.

However, analog color encoders have problems such as unstable operation due to changes in temperature and aging, a large circuit size, and unsuitability for IC implementation. This also applies when a composite signal formed by an analog color encoder is digitized.

Therefore, a digital color encoder has been proposed that can form a composite signal from digitized three primary color data using only digital calculations. B's digital color encoder converts each R, G, and B signal into digital data, multiplies these by a predetermined coefficient, and adds them to form luminance data Y, and combines this luminance data Y with the three primary colors. The color difference data U and V are formed by calculating the data, and the color difference data U and V are digitally modulated and added to the luminance data Y. When the sampling frequency is 4 fSC, the digital modulation is 41 1 as shown in FIG.
One orthogonal component is (-U→-
-■→-2''-+22 ■) at the sampling period in the order of 0' and 90° of the sampling phase.

These four components correspond to each of 180° and 270°.

However, the luminance data 272 color difference data U.

Forming (2) requires a multiplication circuit, which has the disadvantage of increasing the circuit scale. In particular, in cases such as the R, G, and B outputs of a microcomputer, each component data is about 1 or 2 bits, and many arithmetic circuits are required to process such data. It is not a good idea to do so.

``Object of the Invention'' The object of the present invention is to provide a digital color encoder that has a simple circuit configuration and can be mounted at high density when integrated into an IC.

``Summary of the Invention'' The present invention includes a memory storing a data conversion table for converting component data based on sampling phase information and weighting information corresponding to a modulation phase.
This is a digital color encoder in which component data of color video data is input as an address to this memory, and composite data is read from the memory.

EMBODIMENT OF THE INVENTION An embodiment of the present invention will be described with reference to FIG. In FIG. 2, reference numerals 1, 2, and 3 are input terminals to which primary color data R, G, and B are supplied, respectively. The color data R, G, and B are each sampled at a sampling frequency of 4f, and each C1 sample is converted into, for example, 3 bits and 7 bits.

This color data is generated from a source such as a color imaging device or a microcomputer.

The color data of this primary color is ROM 11, 12.

13 address inputs. ROM 11 contains address input (R, G, B) and output data (luminance data Y).
A data conversion table is stored that shows the correspondence with
Similarly, each of the ROM 12 and ROM 13 stores a data conversion table showing the correspondence between address inputs (R, G, B) and output data (RY data and BY data). Luminance data Y1 Color difference data R, -Y
and B-Y are obtained by multiplying each of the color data R, G, and B by a predetermined coefficient and adding them.

The luminance data Y read out from the ROM 11 is supplied to a delay circuit 21 for time adjustment, and the color difference data R-Y and B-Y read out from the ROMs 12 and 13 are supplied to the low/(screen filter 22) of the digital filter configuration. and 23
supplied to The low filters 2 and 23 limit the band of the color difference signal to, for example, 0.5 MHz, and the delay circuit 21 has the amount of delay caused by the low filters 22 and 23.

This delay circuit 21', low filters 22 and 23
Luminance data Y and color difference data RY and B appearing in the output of
-Y is provided to ROM 30 as an address input. This ROM 30 has four sampling phases and four corresponding data conversion tables 31, 32, 33.
34 is stored. The data conversion table 31 has a sampling phase of 08, the data conversion table 32 has a sampling phase of 08, and the data conversion table 33 has output data (Y-40) when the sampling phase is 180°.
'), and the data conversion table 34 generates V). These data conversion tables 31 to 34 generate output data by multiplying the color data RG and B by weight coefficients corresponding to the modulation phase and the sampling phase.

The ROM 30 is supplied with clock pulses as address inputs from terminals 35 and 36 in addition to luminance data Y1 and color difference data RY and BY. The clock pulse from terminal 35 has a frequency 2f shown in FIG. 3A, and the clock pulse from terminal 36 has a frequency fsc shown in FIG. 3B.

These clock pulses have a frequency of 4f. It is synchronized with the sampling clock of As shown in Figure 3, these clock pulses are both low level 4/
4 If the fsc period is T1, the next period is T2, the next period is T3, and the next period is T4,
The data conversion table 31 is selected during the period T1, and the data conversion table 31 is selected during the period T1.
The data conversion table 32 is selected in period T2, the data conversion table 33 is selected in period T3, and the data conversion table 34 is selected in period T4. By repeating this action.

Digital composite color video data is read out from the ROM 30.

This Rolv! 30 output data is supplied to a D/A converter 37, converted into an analog composite video signal, and supplied to an adder 38. This adder 38 is supplied with a burst signal and a synchronization signal from terminals 39 and 40, and the output of the adder 38 is taken out to an output terminal 42 via a low-pass filter 41. This low-pass filter 41 is a Nyquist filter. For example, a video input terminal of a color monitor is connected to the output terminal 42.

If color data R, G, B is 3 bits each, ROM
11, 12, and 13 are the addresses of (29=512). Assuming that the luminance data Y is 4 bits and the color difference data is 2 bits, the address of the ROM 30 will be 10 bits. If the number of bits of the luminance data Y is 4 bits, sufficient image expression can be achieved.

Another embodiment of the invention will be described with reference to FIG. Another example is a video game.

Color data is stored only once, such as in microcomputers.
This invention is applied to the case where the bandwidth is 1 bit or 2 bits and no band limitation is required.

The R2G and B color data supplied from the input terminals 1, 2, and 3 are input to the address of the ROM 50.

ROM 50 has a sampling phase of 00°90°,
Each output data of 180' and 270'(Y'+1
1 1 -U) (Y--V) (Y--U) (Y→-1v > 2
2 2 2 Data conversion tables 51, 52, 53, and 54 generated based on R, G, and B color data have been expanded, and finally, data conversion tables for generating synchronization signals and burst signals. 55 and 56 have also been expanded.

As address inputs to the ROM 50, in addition to color data, clock pulses of 2 fsc and fsc are supplied from terminals 57 and 58, respectively, and a synchronization signal and a burst flag are supplied from terminals 59 and 60. During this synchronization signal period, the synchronization signal data conversion table 55
is selected, and during the burst flag period, the burst signal data conversion table 56 is selected. During these synchronization signal and burst signal periods, the data of the synchronization signal and burst signal of each sampling phase is sequentially read out from the R, OM 50 by two clock pulses.

Reading of composite color video data is performed in the same manner as in the previous embodiment.

Composite color video data including a synchronization signal and a burst signal read out from the ROM 50 is converted into an analog signal by a D/A converter 37, and outputted to an output terminal 42 via a low-pass filter 41. Supplied to a color monitor.

In another embodiment of the present invention, if R, G, and B color data are each 1 bit, the ROM 50 has 7 bits (
=128).

ROM using bipolar transistors has 40 to 60
It operates in [μs] and can sufficiently follow the Zanzo ring period (70 μs) in the case of the NTSC system.

"Application Example" The present invention is applicable not only to primary color signals but also to cases where a luminance signal and two primary color signals (R, B) are supplied.

However, the memory is not limited to a ROM, but a RAM may be used to write a table formed by calculation by a microprocessor into the RAM.

"Effects of the Invention" This invention can perform all the signal processing required in a color encoder by digital processing, so compared to a color encoder with an analog circuit configuration, the present invention has stable operation, miniaturization of two circuits, and IC. It has the advantage of being easy to adapt. Furthermore, compared to digital color encoders that use multiplication circuits, this invention has the advantage of being able to reduce the circuit size and cost, as well as enabling high-density packaging when integrated circuits are used. . In particular, the present invention is effective when used when the number of bits of component signals is small, such as output data of a microcomputer.

Fig. 1 is a route diagram used to explain the formation of a composite signal, Fig. 2 is a block diagram of an embodiment of the present invention, Fig. 3 is a time chart used to explain the operation of an embodiment of the invention, and Fig. 4 is a route diagram used to explain the formation of a composite signal. The figure is a block diagram of another embodiment of the invention.

1.2.3 --- Color data of three primary colors R, G.

■Input terminals to which 3 are respectively supplied, 11, 12, 13゜3
0.50...R ball.

Agent: Tomo Sugiura Figure 1, Figure 4, Figure 2, Figure 3', -T1. -+-■2 T3-+-T4-+:
:l : :+1111

Claims (1)

[Claims] The weighting information corresponding to the sampling phase information and the modulation phase is provided with a memory in which a data conversion table for converting component data is stored, and the component data of the color video data is input as an address to this memory, and A digital color encoder that reads composite data from memory.