JPH06292164A - Video signal processor - Google Patents

Abstract

PURPOSE:To reduce required memory and circuit scale hardly deteriorating picture quality by processing by compressing the number of quantize bits of a high-pass video signal in a video signal. CONSTITUTION:A digital video signal of wide-band is separated to a low-pass video signal and the high-pass video signal, and the high-pass video signal is inputted to a bit compression means 2, and after the number of quantize bits of the high-pass video signal is decreased to the one in which no deterioration of the picture quality occurs, it is transmitted to a signal processing means 20. The signal processing means 20 processes data changed to the one of short bit, and the number of quantize bits is returned to original bit length by a bit extension means 3 after the above processing is completed. A high-pass luminance signal returned to the one of original bits is converted to an analog signal by a D/A conversion part 10, and it is synchronized with the high-pass luminance signal by a delay device 9, and it is added on a low-pass luminance signal converted to the analog signal by the D/A conversion part 10, then, it is outputted as an analog wide-band luminance signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a receiver for receiving a broadcast in which the transmission band of the video signal is compressed by frequency-multiplexing the video signal by sub-sampling, as represented by HDTV. The present invention relates to a video signal processing device that restores high frequency components from a signal.

[0002]

2. Description of the Related Art A conventional video signal processing apparatus is a Multi used in a high definition television receiver (HDTV).
apple Sub-Nyquist Sampling
It is used by being incorporated in an Encoding type decoder (MUSE decoder).

Before describing a conventional MUSE decoder,
A video signal of MUSE will be described (omitted in the case of color signal, sync signal, and moving image). M for still images
The USE video signal is obtained by sampling an image signal having a video frequency bandwidth of about 20 MHz at a sampling frequency of 48.6 MHz, and using the obtained digital data as an original signal.
Sampling frequency conversion from 3MHz to 32.4MHz, and further by inter-frame offset subsampling, after converting to sampling frequency data of 16.2MHz, D / A conversion,
A frequency multiplexed signal (MUSE signal) with a bandwidth of 8.1 MHz is obtained. The MUSE signal is 8.1M as well known by the above-mentioned two times sub-sampling and sampling frequency conversion.
High frequency luminance signal of Hz to 20MHz is about 4MHz to 8.1MHz
It has been folded back to.

A conventional MUSE decoder is shown in FIG.
The portion surrounded by the alternate long and short dash line corresponds to the conventional video signal processing device. The MUSE signal applied to the input (MUSE IN) of the MUSE decoder is passed through a low pass filter (not shown) in the input converter (13) so that aliasing distortion does not occur, and then the A / D converter ( (Not shown) converts analog data into digital data, and the correction unit (14) performs non-linearity, de-emphasis, and gamma correction (not shown), and a video signal processing device as a digital video signal (digital luminance signal). Input to (1).

In the video signal processing device (1), the digital luminance signal is processed by the horizontal low-pass filter (horizontal LPF) (8).
The low frequency image signal (low frequency luminance signal) is separated, and the separated low frequency luminance signal is added to the subtraction inputs of the delay unit (9) and the subtractor (11). On the other hand, a digital luminance signal is added to the subtracted input of the subtractor (11), the preceding low frequency luminance signal is subtracted from the digital luminance signal, and the high frequency video signal is output to the subtractor (11). (High frequency luminance signal) is output. Horizontal LPF
The band of (8) is usually about 4 MHz.

In the case of a still image, the video signal processing device (1)
The high band luminance signal is interpolated by the frame interpolation filter (6) and the sample conversion / field interpolation filter (7) to restore the original high band luminance signal. The frame memory (4) (4) and the field memory (5) are required for this restoration process,
Normally, a first-in / first-out memory (FIFO memory) (41) (Fig. 6) is used for the frame memory (4) and field memory (5), and the number of quantization bits of each sampling data is 8 bits. To be FIG. 6 shows an example in which a 0.5-megabyte frame memory (4) is configured by using a 256Kx 4-bit FIFO memory (41). Two 256k x 4-bit FIFO memories (41) connected to the series to make 0.5 megabyte x 4 are allocated in each of the upper and lower 4 bits, and a total of 4 256k x 4-bit FIFO memories (41 ) Is used.

The restored high-frequency luminance signal is passed through the D / A conversion section.
At (10), it is converted to an analog signal. The high-frequency luminance signal converted into the analog signal is matched in phase with the high-frequency luminance signal by the delay unit (9), and the low-frequency luminance signal converted into the analog signal by the D / A conversion unit (10) and the adder. It is combined in (12) and output as a broadband luminance signal. The D / A converter (10) includes an 8-bit D / A converter (not shown),
Low-pass filter (not shown) that removes clock components
It is composed by.

[0008]

In the above-mentioned conventional video signal processing device (1), since the frame interpolation filter (6) process,
Also, for sample conversion / field interpolation filter (7) processing, a frame memory (4) and a field memory (5) of a few dozen megabits are required, which has a large influence on the circuit scale and the price.

Further, the frequency distribution of the level data (quantization bit number 8 bits) of each pixel of the high-frequency luminance signal of 4 MHz or more in the still life image in the standard picture of the Television Society is as shown in FIG. , Hexadecimal 80 (80H) is concentrated as the center of the peak and the distribution, and the probability of existence of data is low in the range outside 80H on average, and there was some room for consideration. .

The present invention discloses a video signal processing apparatus which solves the above problems by reducing the required memory and the circuit scale without substantially degrading the image quality.

[0011]

The device of the present invention divides a wide band digital video signal into a low band video signal and a high band video signal, adds the high band video signal to a bit compression means (2), and Signal processing means (2
In addition to 0), it is added to the bit expansion means (3) after signal processing.

[0012]

[Operation] The high-frequency video signal of the video signals is input to the bit compression means (2), and the number of quantization bits of the high-frequency video signal is reduced to such an extent that deterioration of image quality does not become a problem, and then signal processing is performed. Transfer to means (20). In the signal processing means (20), the data which has become short bits by compression is processed, and after the processing is completed, the number of quantized bits is returned to the original bit length by the bit expansion means (3).

[0013]

Since the number of quantization bits is compressed and sent to the signal processing means (20), the circuit of the signal processing means (20) can be reduced. Further, when a memory is required for signal processing, the required number of memory bits can be reduced because the number of quantization bits is shortened.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. An embodiment of the present invention is shown within a dashed line in FIG. The configuration and operation from the input of the MUSE signal to MUSE IN to the output of the D / A conversion unit (10) of the low-frequency luminance signal system and the output of the subtracter (11) are the same as the conventional one. .

The 8-bit high-frequency luminance signal output from the subtractor (11) is converted into 6-bit data by the bit compression means (2) having the characteristics shown in the conversion graph of FIG.
Compresses the number of bits of data. In FIG. 2, the horizontal axis represents 8-bit input data and has a range of 0H to FFH, and the bit compressing means (2) stepwise increases from 0H to 3FH for the input range of 6 bits. The data of is output. The conversion graph is based on the distribution of the pixel data of the standard pattern shown in FIG. 5, in which the input data has a high resolution in the vicinity of 80H and the resolution is reduced in other areas. In this embodiment, the conversion table is created in the ROM for implementation.

The input data of the signal processing means (20) is the compressed 6-bit data.
The data of the frame interpolation filter (6), the sample conversion / field interpolation filter (7), the frame memory (4) and the field memory (5), which are the constituent elements of (20), inevitably all have a quantization bit rate. It consists of 6 bits. The frame interpolation filter (6) and the sample conversion / field interpolation filter (7) restore the high frequency luminance signal whose sampling frequency is compressed to 16.2 megasamples to the original high frequency luminance signal of 48.8 megasamples.

Frame memory (4) and field memory
Since the number of quantization bits of the data in (5) is 6 bits,
The configuration shown in FIG. 3 is possible. Two FIs of upper 4 bits
The FO memory (41) is the same as the conventional one, but since the lower order may be 2 bits, one side of the 256k x 4 bit parallel memory 2
By connecting the bit output to the other 2-bit data input, 0.5 mega by 2 bit is realized. By the above method, 0.5 megaword x 6 bit memory (4) is converted into 6 bit 1 word, and 256k x 4 FIFO memory (41)
Can be realized with three. In other words, compared to the conventional one, FI
One FO memory (41) can be omitted.

The 6-bit data processed by the signal processing means (20) is expanded by the bit expansion means (3) from 6 bits to 8 bits in accordance with the conversion graph shown in FIG.
Return to the original luminance signal level. In FIG. 4, the horizontal axis is the 6-bit data after the compressed signal processing, and the vertical axis is the output data of the bit expansion means (3), which is expanded to the original data length of 8 bits. . In the present embodiment, the conversion table is created in the ROM and implemented as in the bit compression means (2).

The high band luminance signal converted to the 8 bits is
The D / A converter (10) converts it to an analog signal, and the delay device (9) synchronizes it with the high-frequency luminance signal, and the D / A converter
By (10), it is added with the low-frequency luminance signal converted into the analog signal and output as an analog wide-area luminance signal.
The D / A converter (10) is composed of an 8-bit D / A converter (not shown) and a low-pass filter (not shown) that removes a clock component.

As described above, according to the present invention, it is possible to reduce the circuit scale of the video signal processing apparatus and to reduce the number of required memory bits when a memory is required for processing without degrading the image quality. . In the above description, only the still image has been described, but the still image has a higher required resolution than the moving image.

The above description of the embodiments is for explaining the present invention and should not be construed as limiting the invention described in the claims or reducing the scope. The configuration of each part of the present invention is not limited to the above-mentioned embodiment, and it goes without saying that various modifications can be made within the technical scope described in the claims. In the present embodiment, the case where the present invention is applied to the MUSE decoder and the data length of the high-frequency luminance signal is converted from 8 bits to 6 bits has been described, but this is to facilitate understanding of the invention. It does not limit the invention. Further, although the conversion graphs shown in FIGS. 2 and 4 are used for compressing and expanding the data, it goes without saying that the conversion graphs can be variously modified.

[Brief description of drawings]

FIG. 1 is a block diagram of a video signal processing device (inside a broken line) of the present invention.

FIG. 2 is a data conversion graph of bit compression means.

FIG. 3 is a block diagram of a configuration example of a memory of 0.5 megawords × 6 bits.

FIG. 4 is a data conversion graph of bit expansion means.

FIG. 5 is a frequency distribution table of 8-bit data of a standard image (still life) image.

FIG. 6 is a block diagram of a configuration example of a 0.5 mega × 8 bit memory.

FIG. 7 is a block diagram of a conventional video signal processing device (inside a broken line).

[Explanation of code] (2) Bit compression means (3) Bit expansion means (20) Signal processing means

[Procedure amendment]

[Submission date] July 2, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

Before describing a conventional MUSE decoder,
A video signal of MUSE will be described (omitted in the case of color signal, sync signal, and moving image). M for still images
The USE video signal is an image signal with a video frequency bandwidth of about 20 MHz, sampled at a sampling frequency of 44.55 MHz, and the resulting digital data is time-compressed to 12/11 times and the 48.6 MHz rate signal is used as the original signal , The original signal is subjected to inter-field offset sub-sampling, then sampling frequency conversion from 48.6 MHz to 32.4 MHz, and further inter-frame offset sub-sampling to data having a sampling frequency of 16.2 MHz, D / A converted, A frequency multiplexed signal (MUSE signal) with a width of 8.1 MHz is obtained. The MUSE signal is 8.1 MHz as known by the above-mentioned two times of sub-sampling and sampling frequency conversion.
The high-frequency luminance signal of ~ 20MHz is folded back to about 4MHz ~ 8.1MHz.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

The input data of the signal processing means (20) is the compressed 6-bit data.
The data of the frame interpolation filter (6), the sample conversion / field interpolation filter (7), the frame memory (4) and the field memory (5), which are the constituent elements of (20), inevitably all have a quantization bit rate. It consists of 6 bits. The frame interpolation filter (6) and the sample conversion / field interpolation filter (7) restore the high frequency luminance signal whose sampling frequency is compressed to 16.2 megasamples to the original high frequency luminance signal of 48.6 megasamples.

Claims (1)

[Claims] 1. A video signal processing apparatus for dividing a wideband digital video signal into a low-frequency video signal and a high-frequency video signal, processing the signals separately, and synthesizing the processed video signals. A video signal processing device characterized in that, in addition to the bit compression means (2), a bit-compressed high-frequency video signal is added to the signal processing means (20) and, after signal processing, added to the bit expansion means (3).