JPH02181595A - Expansion circuit - 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] [Object of the Invention] (Industrial Application Field) This invention compresses a video signal including a luminance signal and a color signal at a first compression rate, and compresses the color signal out of the compressed output. Further, the luminance signal is compressed at a second compression rate, and the luminance signal obtained by multiplexing the color signal compressed at the first degree compression rate onto the horizontal blanking period of the luminance signal compressed at the first compression rate. The present invention relates to an expansion circuit that expands a chromaticity time-division multiplexed signal to obtain an original video signal.

(Prior Art) In recent years, in television broadcasting, due to the development of digital technology, the method of transmitting television signals is to compress the color signal on the time axis, convert it into a line-sequential signal, and then
A luminance/chromaticity time-division multiplexing method has been developed that multiplexes luminance signals in a time-division manner during the horizontal retrace period.

On the other hand, in recent television broadcasting, the aspect ratio of the screen has been changed from the current 4:3 to 5 to increase the sense of realism.
A wide aspect ratio that expands to 3 or 16:9 is being considered.

However, when wide aspect ratio is performed, the horizontal retrace period of the luminance signal is shortened, so it may become impossible to time-division multiplex the color signal whose time axis is compressed.

Therefore, in such a wide aspect method,
When adopting the luminance/chromaticity time division multiplexing method, first, the portion of the video signal including the luminance signal and chrominance signal other than the horizontal blanking period is compressed by about 10%, and the chrominance signal included in this compressed output is compressed by about 10%. A method is adopted in which the compressed signal is further compressed and the compressed output is multiplexed into the horizontal retrace period.

FIG. 2 is a circuit diagram showing the configuration of a conventional decompression circuit that decompresses the luminance/chromaticity time-division multiplexed signal compatible with the wide aspect ratio described above to obtain the original video signal.

In this FIG. 2, the luminance signal supplied to the input terminal 11
The chromaticity time-division multiplexed signal is supplied to an inverse matrix circuit 12 and a chrominance signal expansion circuit 13.

The color signal expansion circuit 13 expands the color signal of the input signal at a rate corresponding to the compression ratio of the luminance signal and the color signal. This decompression process is performed, for example, by using a line memory and changing its writing speed and reading speed.

The output of the color signal expansion circuit 13 is vertically interpolated by a vertical interpolation circuit 14 and then supplied to the inverse matrix circuit 12 via sample rate conversion circuits 15 and 16. The inverse matrix circuit 12 reproduces primary color signals R, G, and B from the luminance signal supplied from the input terminal 11 and the color signals supplied from the sample rate conversion circuits 15 and 16.

These primary color signals R, G, and B are each supplied to a primary color signal expansion circuit 1.
At No. 7, 18, and 19, the signals are expanded at an expansion ratio corresponding to the compression ratio of 10%, thereby converting them into primary color signals R, G, and B having the original time lengths.

This time expansion is also performed using, for example, a line memory. These primary color signals R, G, and B are transmitted through digital/analog conversion circuits (hereinafter referred to as D/A conversion circuits) 20,
After being converted into analog signals by 21.22, unnecessary components are removed by low-pass filters (hereinafter referred to as LPF) 23, 24.25, and the signals are supplied to output terminals 26, 27.28.

These primary color signals R, G, and B are supplied to a monitor (not shown) and used for image display.

As mentioned above, the conventional decompression circuit first decompresses only the color signal to equalize the compression ratio of the color signal and luminance signal, and then
By using this luminance signal and color signal to obtain primary color signals R, G, and B, and finally expanding these primary color signals R1G and B, primary color signals R, G, and B having the original time length are obtained. It has become.

However, in such a configuration, an independent line memory is required for each of the primary color signals R1G and R1B, so there is a problem that the number of line memories increases and the hardware becomes large.

Furthermore, since the output signal of the inverse matrix circuit 12 is 9 bits or more even if the input signal is 8 bits, a line memory with a large capacity is required, resulting in the problem of increased hardware size.

Furthermore, in high-frequency enhancement of video signals and recent video signal processing, the video signal is processed while returning it to a linear signal, so it is necessary to apply monitoring characteristics to the output signal of the inverse matrix circuit 12. However, there was a problem in that the line memory capacity increased.

(Problems to be Solved by the Invention) As described above, in the conventional expansion circuit that expands the luminance/chromaticity time-division multiplexed signal to obtain the original video signal, the primary color signals R, G, which are the final output, Since decompression processing is performed on B, there is a problem in that the number and capacity of line memories increases, and the hardware becomes larger.

Therefore, an object of the present invention is to provide an expansion circuit that can reduce the number and capacity of line memories and can be realized with small hardware.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides an expansion ratio for a luminance signal included in a luminance/chromaticity time-division multiplexed signal that corresponds to a compression ratio of a video signal. and means for expanding the color signal by the product of the expansion ratio corresponding to the compression ratio of the color signal and the expansion ratio corresponding to the compression ratio of the video signal.

(Example of operation) As described above, according to the configuration in which decompression processing is performed before converting the luminance/chromaticity time-division multiplexed signal into a primary color signal, two memories are provided as line memories, one for luminance signals and one for chrominance signals. Therefore, the number of line memories can be reduced.

Furthermore, since the number of bits of the signal does not increase in the stage before conversion to the primary color signal, the capacity of the line memory can also be reduced.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In the following explanation, the compression ratio of the video signal is 11/12.
, a case where the color signal compression ratio is 1/4 will be explained as a representative case.

FIG. 1 is a circuit diagram showing the configuration of an embodiment of the present invention.

In FIG. 1, the luminance signal supplied to the input terminal 31
The chromaticity time-division multiplexed signal is supplied to a luminance signal expansion circuit 32 and a chrominance signal expansion circuit 33. The luminance signal expansion circuit 32 expands the luminance signal included in the luminance/chromaticity time-division multiplexed signal at an expansion ratio of 12/11 corresponding to the compression ratio of the video signal of 11/12. The color signal expansion circuit 33 converts the color signal included in the luminance/chromaticity time-division multiplexed signal into a video signal at a compression ratio of 11/1.
2 corresponds to an expansion ratio of 12/11 and a color signal compression ratio of 1/4.
It is expanded at an expansion ratio of 48/11, which is the product of the expansion ratio 4 corresponding to .

Note that the decompression processing of these decompression circuits 32 and 33 can be realized by using a line memory and making the write speed and read speed different.

In this case, a RAM can be used as the line memory, but in addition to this, for example, a FIFO (first-in-first-out memory) may also be used.

The luminance signal expanded by the luminance signal expansion circuit 32 is supplied to an inverse matrix circuit 34. The one color signal expanded by the color signal expansion circuit 33 is vertically interpolated by the vertical interpolation circuit 35 and then supplied to the inverse matrix circuit 34 via sample rate conversion circuits 36 and 37. This inverse matrix circuit 34 generates primary color signals R and G from the time-expanded luminance signal and color signal.

Play B. These primary color signals R, G, and B are each D/
After being converted into analog signals by A conversion circuits 38, 39.40, unnecessary components are removed by LPFs 41, 42.43, and the signals are supplied to output terminals 44, 45.46. These primary color signals R, G, and B are supplied to a monitor (not shown) and used for image display.

As described above, in this embodiment, the decompression process is completed before converting the luminance/chromaticity time-division multiplexed signal into the primary color signals R, G, and B.

According to such a configuration, it is only necessary to have two line memories for decompression, one for luminance signals and one for color signals, and as in the past, one for color signals and one for each primary color signal R, Compared to the case where four memories, including those for G and B, are required, the number of line memories can be reduced to half.

Furthermore, in this embodiment, the decompression process is performed before the number of signal bits increases, so not only can the number of line memories be reduced, but the capacity of each line memory can also be significantly reduced compared to conventional methods. can.

In addition, the conventional expansion circuit 17.1 for primary color signals R, G, and B
8.19 is deleted, a luminance signal expansion circuit 32 is provided in its place, and the conventional chrominance signal expansion circuit 13 can be used as the chrominance signal expansion circuit 33 by simply changing the readout clock frequency. is also easy.

Although one embodiment of the present invention has been described in detail above, this invention is not limited to the previous embodiment, and it goes without saying that various modifications can be made without departing from the gist of the invention. be.

[Effects of the Invention] As described above, according to the present invention, the expansion processing is performed at the stage of the luminance signal and chrominance signal before converting the luminance/chromaticity time-division multiplexed signal into the primary color signal. The number of memory ohms and capacity can be reduced, and the hardware can be downsized.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of an embodiment of the present invention, and FIG.
The figure is a circuit diagram showing the configuration of a conventional expansion circuit. 31... Input terminal, 32... Luminance signal expansion circuit, 3
3... Color signal expansion circuit, 34... Inverse matrix circuit, 35... Vertical interpolation circuit... 36.37... Sample rate conversion circuit, 38, 39.40... D/A conversion Circuit, 41.42.43...LPF, 44,45.
46...Output terminal.

Claims (1)

[Claims] A video signal including a luminance signal and a color signal is compressed at a first compression rate, and the color signal of this compressed output is further compressed at a second compression rate. Expanding the luminance/chromaticity time-division multiplexed signal obtained by multiplexing the color signal compressed at the compression rate into the horizontal retrace period of the luminance signal compressed at the first compression rate to obtain the original video signal. In the circuit, the above luminance and
The first step expands the luminance signal included in the chromaticity time-division multiplexed signal.
and a third expansion rate corresponding to the product of a second expansion rate corresponding to the second compression rate and the first expansion rate, and included in the luminance/chromaticity time division multiplexed signal. An expansion circuit comprising: second expansion means for expanding a color signal.