JPS60145792A - Inter-frame encoding system - Google Patents

Abstract

PURPOSE:To simplify a forecasting circuit and to minimize the scale of the circuit by encoding a luminance signal by the two-dimensional forecast encoding method and a chrominance signal by the one-dimensional forecast encoding method. CONSTITUTION:A luminance signal and a chrominance signal which constitute a color picture information signal are encoded respectively. In an inter-frame encoding system which is digital-transmitted by multiplexing time sharing, the luminance signal is encoded by a two-dimensional forecast encoding method 8 and the chrominance signal is encoded by a one-dimensional forecast encoding method 9. In this case, only one-picture element delay element is enough for a chrominance-signal one dimensional forecasting circuit 9 if the picture element immediately before the element which shall be encoded is used. Therefore, the constitution of both transmitting and receiving is remarkably simplified. In addition, since the luminance signal is encoded by the two-dimensional forecast encoding method, the picture quality is not deteriorated.

Description

Detailed Description of the Invention (Technical Field) The present invention provides a color image I1 consisting of a luminance signal and a color signal.
1 report No. 44, for example, composite color television signal si j no child i1+11? Regarding the Q-encoding system, in particular, an intra-frame encoding system with good image quality that can reduce the size of the circuit configuration.
There is a molecular met coding method as an intra-frame coding method, which is one of the predictive coding methods for signals. Regarding this method, NT
SC color television signal (hereinafter referred to as ``NTS'')
To explain simply using the example "C signal",
Process the NTSO signal with the luminance signal Y.

Q is once separated into two color signals ClIC8, and time-compressed using the narrow frequency band of each color code C□, 02, and this time-compressed color signal C1°0.2 is converted into a luminance code Y time-division multiplexing in the horizontal blanking period of
In this way, the luminance signal Y and the color signal C□.

A device that performs intra-frame encoding processing on a time division multiplexed signal (hereinafter referred to as "TDM signal") in which OQ (hereinafter each of these two color signals is referred to as "G□ signal J + ra2 signal") is time division multiplexed. It is.

The signal format of the TDM signal in such a system is usually configured as shown in FIG.

That is, the C signal of the nth line is inserted into the horizontal blanking period of the nth line, the C8 signal of the nth line is inserted into the horizontal blanking period of the (n+x)th line, and the C signal of the nth line is inserted into the horizontal blanking period of the (n+z)th line. □, C2 signal is ignored. In addition, Q 24g of the nth line, No. (n+x)
Another possible method is to ignore the line C signal. th (n
+2) For lines after the line, the color signals of every other line are similarly ignored.

The receiving side reproduces the color signal of the ignored line by interpolating it using, for example, the color signals of the previous and subsequent lines. Note that the Y signal is multiplexed on all lines.

When performing an intraframe coding method for two-dimensional prediction that utilizes correlation in the horizontal and vertical directions for such a TDM signal, conventionally, the pixel arrangement in the frame shown in Figure 2 was When encoding X, when encoding a Y signal, the immediately preceding pixel A and each pixel B on the l line in the same field.

Or D is used to configure the predicted value
, a2 are arranged alternately in one line, so the pixels B' and C' on two lines in the same field.

Predicted value X using D' and the previous pixel. was constructed as shown in equation (2).

X,=Ta+,d+T(C-b) -----(1)?
. =-! -a'juku d'jucho (C'-b') -----
-(2) where a, b, c, d and a/, b/
, CI, d/ are the luminance information pixel values of pixels A, B, O, D and A/.

It represents the color information pixel values of B/, G/, and DI, respectively.

That is, for the pixel value of pixel
And for the Cg double signal, the predicted value X for each color signal obtained from the above equation (2). The difference value between the pixel value and each pixel value of the pixel X represented by each color signal is quantized and decoded.

In this way, in the conventional Yuzu method, the predicted values are X for the C signal and the C2 signal, respectively. In calculating l1iIT, as is clear from Figure 2, the O to be encoded is
2 from the current pixel X line for the R+ 02 signal
Since each of the 1lliJ elements Bl, CI, and DI on the line is used, two
This method requires a line memory, which increases the circuit size, and has the disadvantage that two-dimensional prediction circuits for color signals, which are large in circuit size, must be provided on both the transmitting and receiving sides of the transmission system.

(Object of the Invention) An object of the present invention is to eliminate the drawbacks of the conventional intra-frame encoding method as described above, and to improve the color signal prediction circuit by performing one-dimensional prediction and encoding for the color signal. The present invention aims to provide an intra-frame encoding method for color image information signals that is simplified and allows the circuit scale to be hand-carved.

(Structure and operation of the invention) In order to achieve the above object, the intraframe encoding method of the present invention encodes each of the luminance signal and color signal that constitute a color image information signal, time-division multiplexes the signals, and digitally transmits the signals. In the intra-frame encoding method, a luminance signal is encoded using a two-dimensional predictive encoding method, and a color signal is encoded using a one-dimensional predictive encoding method.

As in the method of the present invention, the luminance signal is encoded by a two-dimensional predictive code saving method, and the color signal does not require a one-dimensional predictive code, so the circuit scale is extremely simple and can be fully hand-engraved. For example, one-dimensional prediction flI! If the pixel immediately before the pixel to be encoded as I is used, the color signal one-dimensional prediction circuit can be a one-pixel delay element such as a D flip-flop, so the configuration of both the transmitter and receiver is as follows. Extremely simplified. Moreover, the luminance signal is different from the conventional 41
11 method, it is encoded using the two-dimensional predictive encoding method, so it can encode color television signals without any loss in image quality compared to the conventional intra-frame encoding method.
Color image 11'7 information signals such as color facsimile signals can be encoded and digitally transmitted.

(Embodiment) FIG. 8 is a block diagram showing an example of an embodiment of the method of the present invention. In the figure, l is a color image information signal, for example, NTS (3 signal input terminals, 2 and 24 are filters,
8 is an A/D conversion circuit, 4 is a color separation/time division multiplexing circuit, 5
is a subtracter, 6 is a quantization circuit, ? and 18 is an adder, 8
and 19 are two-dimensional luminance signal prediction circuits, 9 and 20 are one-dimensional color signal prediction circuits, lO is a clock generation circuit, and 11
17 is a code conversion circuit, 12 and 16 are digital interfaces, 18 is a data output terminal, 14 is a digital transmission line, 15 is a data input terminal, 21 is a clock regeneration circuit, 22 is a color synthesis/time division separation circuit, and 28 is a D/
A conversion circuit, 25 is an NTSO signal output terminal, and 100 and 101 are switches that are switched by respective switching signals from respective clock recovery circuits 10 and 21 for both transmission and reception.

In such a configuration, the NTSO signal input from the NTSO signal input terminal 7-1 is band-limited by the filter 2, and then guided to the A/D converter 3 and converted into a digital signal. Next, the color separation/time division multiplexing circuit 4 separates the luminance signal Y into the two color 1d signals C□ and 02 of color and Q, and the signal format is roughly shown in FIG. 1 in the same circuit 4. , color signals C, C2 corresponding to the luminance signals of every other line are converted into TDM signals that are sequentially inserted into the blanking period of each line. This TDM signal is subtracted from the subtracter 5 by each predicted value from the two-dimensional prediction circuit for luminance signal 8 and the one-dimensional prediction circuit for color signal 9, which are applied to the subtracter 5 in a time-divisional manner via a switch 100. , the difference value is quantized by the quantization circuit 6. The output of the quantization circuit 6 is time-divisionally added with each predicted value by a W adder 7, and becomes a locally decoded signal. The locally decoded signal is supplied to a two-dimensional luminance signal prediction circuit 8 and a one-dimensional color signal prediction circuit 9. The luminance signal two-dimensional prediction circuit 8 performs an operation according to a predetermined two-dimensional prediction function, for example, the operation of the child 111Il function XY shown in equation (1) above, and outputs the predetermined value of the operation result to the switch 100. . Further, the color signal prediction circuit 9 uses a predetermined one-dimensional prediction function, for example,
A predicted value according to the prediction is output to the switch 100. Note that the switch 100 is controlled by a switch switching signal from the clock generation circuit IO, and outputs the output of the luminance signal two-dimensional Yome Oki 1-8 during the luminance signal period, and outputs the output of the luminance signal 2-dimensional Yome Oki 1-8 during the horizontal blanking period when the color signal is superimposed. Color signal one-dimensional prediction circuit 9
is selected and guided to the n reducer 5. Note that the clock generation circuit 1O may be of a well-known configuration that is widely and generally used in the field of linear processing of television signals. is supplied to each unit that requires a clock, such as the predictive encoding unit. On the other hand, as part of this, a switch switching signal is generated to distinguish between the luminance signal period and the color signal superimposition period, and this signal is sent to the switch 1.
00 for switching operation.

In this way, for the luminance signal Y, the two-dimensional element N11
Using the color signal 01. For O, a one-dimensional predicted value, for example, the immediately preceding pixel value is used as the predicted value, and the difference values from the current value are respectively guided to the quantization circuit 6 in a time-sharing manner to obtain a quantized output. This quantized output is assigned a predetermined code by a code conversion circuit 11, and is converted into a signal format on a transmission path by a digital interface 12, for example, bipolar (AM I).
: alternatemark 1nversion
) The data is converted into code and sent to the digital transmission path 14 via the data output terminal 18.

In the receiving section, the data input from the data input terminal 15 is converted into a signal format that can be decoded by the digital interface 16, and then converted by the code conversion circuit 17 into a format that can perform four arithmetic operations, for example, a two's complement format signal. do. In addition, the digital interface 16 separates the sampling frequency information on the transmitting side from the received data, and
This is supplied to the clock regeneration circuit 21. The clock reproducing circuit 21 reproduces various clock signals necessary for video decoding based on the sampling frequency information signal from the digital interface 16, and supplies these to each section that requires clock signals. At the same time, as part of this, a switch 101 is installed to selectively guide each signal of the luminance signal period and the horizontal blanking period into which the color signals C□ and c2 are inserted to the adder 18, similar to the clock generation circuit IO on the transmitting side.
A switch switching signal is generated to control the switch 101, thereby operating the switch 101.

A predicted value regarding the luminance signal is sent from the luminance signal two-dimensional prediction circuit 19 to the luminance signal period signal via the switch 101.
In addition, predicted values are added to the color signal in the horizontal blanking period from the color signal one-dimensional prediction circuit 20 to form a decoded signal, which is then processed by the luminance signal two-dimensional prediction circuit 19, the color signal one-dimensional prediction circuit 20, and the color synthesis/time signal. The signal is supplied to each of the division/separation circuits 22. The two-dimensional luminance signal prediction circuit 19 has the same configuration as the luminance signal prediction circuit 8 of the transmitting section, and the one-dimensional color signal prediction circuit 20 has the same configuration as the one-dimensional color signal predicting circuit 9 of the transmitting section. be. Furthermore, the same prediction function is used for both transmission and reception.

The TDM signal decoded in this manner is processed as a luminance signal by the color synthesis/time division separation circuit 22.

Time-division separation is performed into color signals C1, C, and color signals Y, I, and Q, respectively, and each color signal 01. After time extension for O, NTSo
The luminance signal Y is combined with the luminance signal Y so as to have a signal format.

This digitized NTSO signal is converted into an analog signal by the D/A conversion circuit 28, band-limited by the filter 24, and sent to the NTSO signal output terminal 25.

In the above embodiment, the predicted value of the luminance signal is based on the equation (1) above, and the color signal C□.

Regarding C2, an example of previous value prediction has been described, but the method of the present invention is not limited to using these predicted values. Furthermore, as for the transmission code, either a fixed length code or a variable length code can be applied. When variable length codes are used, speed smoothing buffer memories are used in each of the digital interfaces 12 and 16.

In the above embodiment, a case was described in which an NTSO signal was encoded, but the method of the present invention is applicable to the PAL method, SEO
Of course, it can also be applied to a composite color television No. 18 in which a luminance signal and two color information No. 18 are frequency-multiplexed, such as an AM system, and a color facsimile signal having the same structure as that color television signal. Not only such a composite color image information signal but also a luminance signal Y and a color signal C□.

It is also applicable when C8 is input separately,
Such embodiments are also included in the present invention. In this case, the color separation/time division multiplexing circuit 4 and the color synthesis/time division separation circuit 22 in the configuration of the embodiment shown in FIG. 8 become unnecessary.

In addition, in the method of the present invention, the color signal refers to a form determined by the configuration of the color image information signal, such as I and Q color signals in the NTSO signal, color difference signals such as (RY) #(B-Y), and primary color signals. shall mean various color information signals.

(Effects of the Invention) As explained in detail above, the system of the present invention time-division multiplexes the luminance signal and chrominance signal of a color image information signal consisting of a luminance signal and a chrominance signal, such as a composite color television signal. In the intra-frame encoding method for digitally transmitted color image h7 report signals, the luminance signal is encoded using the conventional two-dimensional predictive encoding method, and the color signal is encoded using the simplest prediction circuit for predicting the previous value. Encoding is performed using a one-dimensional predictive encoding method that suffices by using a one-pixel storage element such as a D flip-flop. Therefore, according to the method of the present invention, in the conventional intra-frame encoding method in which both luminance signal and chrominance signal are two-dimensionally predictively encoded, a two-line memory is required as a component of the prediction circuit for the chrominance signal. can be omitted, making it possible to downsize the circuit scale of both the transmitting and receiving color signal prediction circuits.However, since the luminance signal is subjected to two-dimensional predictive coding as before, the image quality is reduced. The method can encode and digitally transmit color image information signals with no inferiority compared to conventional methods.

[Brief explanation of drawings]

Figure 1 is a diagram to explain the 7-ohm mat of the TDK signal, which is time-division multiplexed with the luminance signal of the color television signal and two color signals. Figure 2 is the diagram of conventional two-dimensional predictive coding. FIG. 8, which is a diagram for explaining the pixel arrangement used in the two-dimensional prediction of the method, is a block diagram showing the configuration of one embodiment of the method of the present invention. ■...NTSC signal input terminal 2.24...Filter 3...A/p conversion circuit 4...Color separation/time division multiplexing circuit 5...Subtractor 6...-fftft assimilation circuit 78...・
Adder 8, 19... Two-dimensional prediction circuit for luminance signal 9.20... One-dimensional prediction circuit for color signal l1111 circuit IO.
... Clock generation circuit 11.1... Code conversion circuit 12.16... Digital interface 18...
Data output terminal TODO...Digital transmission line 15...Data input terminal zl...Clock regeneration circuit 22...Color synthesis/time division separation circuit 28...D/A conversion circuit 25...NTSO signal Output terminal 100.101...Switch. Patent applicant Nippon Telegraph and Telephone Corporation

Claims (1)

[Claims] l. Luminance signal and color 6S that constitute the color image information signal
In the intra-frame coding method in which each i is coded, time-division multiplexed, and digitally transmitted, the luminance signal is coded using the two-dimensional predictive coding method G, and the chrominance signal is coded using the first-order iQ predictive coding method. This is an intra-frame encoding method that is characterized by the following: