JPH10126746A - Signal format for image signal, format conversion method for image signal and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate image processing in a computer and data compression by selecting the number of lines for a valid scanning lines to 576 and to 1024 for a valid horizontal pixel. SOLUTION: As a sequential scanning system digital component coding adopted by the PAL/SECAM systems, the 2.4:2:2p (625) system and the 4:2:0p (625) system are considered. The valid scanning line number is 576 and the valid horizontal pixel number is 720, and the aspect ratio is 16:9. In order to obtain square pixel arrangement without changing the number, 576, the number of pixels is to satisfy 16/9×576=1024. Furthermore, since image data quantity is huge when non-compression is adopted in the case of recording/transmission of image data, data compression is required. In the case of the JPEG or the MPEG, one block for DCT transformation is 8×8 pixels and color difference information adopts a sample point a half of that of luminance, then a multiple of 16 is advantageous for number of pixels. Then 1024 is adopted for the number of horizontal valid pixels, each pixel is arranged as a square pixel form and the image processing by a computer is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a signal format and conversion technique for an image signal, and more particularly to a signal format and conversion technique for a television signal.

[0002]

2. Description of the Related Art As is well known, there are roughly three types of television systems in the world. That is, the NTSC system used in Japan and the United States, and the PAL and SECAM systems used in Europe and the like. NTS mentioned above
In each of the C system, PAL, and SECAM system, a luminance signal component and a chrominance signal component obtained by modulating a carrier are frequency-multiplexed. The method of collectively converting these signals into digital signals is called composite coding.

However, NTSC, PAL, SECA
Since each of the M systems employs a different signal modulation system, there is no compatibility between these signals. Therefore, the composite encoded digital image signal cannot be used in different television systems. By the way, a method of independently converting a luminance signal and a color difference signal obtained by linear conversion of R, G, and B signals constituting a television signal into digital codes is called component coding. By using this component coding, at least there is no need to be bothered by the difference in the modulation method of the color signal.

[0004] In order to reduce the cost of digital video equipment, the ITU-R, which is an advisory body of the ITU, has proposed "encoding parameters for digital television for studios" as a unified standard. This is shown in FIG. On the other hand, in recent years, the scanning method is shifting from the interlace method to the sequential scanning method due to a demand for high image quality. In the NTSC area, 525-line sequential scanning (hereinafter referred to as 525p) is performed by sampling a luminance signal of an analog signal at a frequency of 27 MHz and sampling a color difference signal at a frequency of 13.5 MHz as a typical digital component coding of a progressive scanning method. 4: 2: 2p method, a luminance signal of a 525 progressive scanning analog signal is sampled at a frequency of 27 MHz, and a color difference signal is sampled at 6.75 MHz.
Method is known). These 4: 2: 2p
The system and the 4: 2: 0p system have an effective scanning line number of 480.
In this case, the number of effective horizontal images is 720 pixels, and the aspect ratio is 16: 9.

As described above, it is considered that the scanning method will shift from the interlace method to the sequential scanning method, and there is a great possibility that the scanning method will naturally shift to the PAL and SECAM zones. As the digital component coding of the progressive scanning system adopted in the PAL and SECAM spheres, the above-mentioned “coding parameter of digital TV for studio” is used.
From the background, a method of sequentially sampling 625 lines (hereinafter referred to as 625p, a method of sampling a luminance signal of an analog signal at a frequency of 27 MHz and sampling a color difference signal at 13.5 MHz (hereinafter referred to as 4: 2: 2p (625)). .)
And the luminance signal of the 625p analog signal at a frequency of 27 MHz.
z, and a color difference signal is sampled at 6.75 MHz (hereinafter, referred to as 4: 2: 0p (625)). The number of effective scanning lines is 576, and the number of effective horizontal images is 720 pixels. And its aspect ratio is 1
6: 9.

On the other hand, with the recent rise of computers,
Images are also often processed by computers.
By the way, since the image data has a huge data amount, when the image is digitized and transmitted or recorded on a recording medium such as a CD-ROM or a hard disk, it is usually compression-coded. Among the compression coding methods, a coding method based on DCT, which performs compression using the property that the spatial frequency of an image is concentrated at a low frequency, is used relatively frequently. This is JPEG (Joint Photographic Experts
Group) and MPEG (Moving Picture Experts Group).

FIGS. 5 to 10 show the hierarchy of the code format conforming to MPEG. MPEG codes have several hierarchical structures as shown in FIG. The top layer is the video sequence shown in FIG.
It is composed of OP (Group Of Picture). The GOP is composed of a plurality of pictures as shown in FIG. One picture indicates one image. There are three types of pictures: an I-picture which is an intra-frame code, a P-picture which is an inter-frame code only in the forward direction, and a B-picture which is an inter-frame code both before and after.

A picture is composed of a plurality of slices divided into an arbitrary area as shown in FIGS. A slice is composed of a plurality of macroblocks arranged in left-to-right or top-to-bottom order. As shown in FIGS. 9 and 10, the macro block is obtained by further dividing the block of 16 × 16 dots into blocks of 8 × 8 dots and dividing the luminance component (Y
1, Y2, Y3, Y4) and 8
It consists of six blocks of color difference components (Cb, Cr) of a block of × 8 dots.

Therefore, it is assumed that a picture is divided into blocks of 16 × 16 dots.

[0010]

The above-mentioned 4: 2: 2p (625) system and 4: 2: 0 which are expected in the future.
The p (625) method has 576 effective scanning lines, 720 effective horizontal images, and an aspect ratio of 1 pixel.
6: 9. Therefore, the shape of each pixel is not a square (square) but a 4: 2: 2p (625) method and a 4: 2: 2p (625) method.
Image signals of the 2: 0p (625) system cannot be easily processed by a computer. This is because, when an image is processed by a computer, for example, when an image is rotated on a screen, if the shape of each pixel is not square, the rotated image has a different shape from the original image.

It is an object of the present invention to provide an image signal which can be easily processed by a computer and which can easily perform data compression, particularly a signal format of a television signal, and a technique for converting a conventional image signal into the image signal. Is to provide.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to provide a signal format of an image signal, wherein the number of effective scanning lines is 576.
This is achieved by a signal format of an image signal characterized in that the number of effective horizontal pixels is 1024.
Another object of the present invention is a signal format of an image signal, wherein the aspect ratio is 16: 9, the number of effective scanning lines is 576, and the number of effective horizontal pixels is 1024. Is achieved by the following signal format.

In this signal format, the shape of each pixel is square, and the number of pixels in the vertical and horizontal directions is a multiple of 16, so that the JPEG or MPEG compression encoding method can be used as it is. An object of the present invention is a signal format of an image signal, wherein the sampling rate of luminance data in a progressively scanned image signal in which the number of effective scanning lines per field is 576 and the number of horizontal effective pixels is 720 is 64 /. Converted to 45 times and the number of effective horizontal pixels is 1
This is achieved by an image signal format conversion method characterized in that the image signal is converted into a progressive scanning image signal of 024 pixels.

The number of effective scanning lines per field is 57
In the case of a progressively scanned image signal having six lines and 720 horizontal effective pixels, the luminance data sampling rate is set to six.
The number of effective horizontal pixels is 1024 just by converting to 4/45 times
Can be changed to pixels. Although the number of effective horizontal pixels and the number of horizontal sampling of luminance data usually match,
It does not match the horizontal sampling number of the color difference data. Therefore, in the present invention, it is sufficient that the horizontal sampling number of the luminance data is 1024 at minimum, and the horizontal sampling number of the color difference data is generally set to 1024 / integer. The most common value is 1024/2.

An object of the present invention is to provide an apparatus for converting a signal format of an image signal, wherein the number of effective scanning lines per field is 576 and the number of horizontal effective pixels is 720. And a means for converting the sampling rate of the luminance data into 64/45 times and converting it into a progressively scanned image signal having an effective horizontal pixel number of 1024 pixels.

It is another object of the present invention to provide an image processing apparatus in which the number of effective scanning lines per field is 576 and the number of horizontal effective pixels is 72.
An apparatus for converting a format of zero progressively scanned image signals, wherein said means generates a first clock signal having a frequency 64 times a sampling frequency of luminance data in said progressively scanned image signals; Means for inserting zero data into the luminance data of the progressively scanned image signal based on the clock signal, and applying a low-pass filter;
First frequency dividing means for dividing the first clock signal by 45, and means for thinning out luminance data into which zero data has been inserted based on the clock signal divided by the first frequency dividing means. Means for generating a second clock signal having a frequency which is 64 times the sampling frequency of the color difference data in the progressive scan image signal; and inserting a zero data into the color difference data based on the second clock signal; Means for multiplying the second clock signal by 45
A conversion comprising: second frequency dividing means for frequency dividing; and means for thinning out color difference data into which zero data is inserted, based on the clock signal divided by the second frequency dividing means. Achieved by the device.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the signal format of the present invention will be described. The signal format of the present invention is shown in FIG.
As shown in the figure, on a screen with an aspect ratio of 16: 9,
The number of effective scanning lines is 576, and the number of effective horizontal pixels is 1024.

[0018]

As described above, the progressive scanning digital component coding adopted by the PAL and SECAM systems includes 4: 2: 2p (625) system and 4: 2: 0.
The p (625) method is considered, and the number of effective scanning lines is 576.
In this case, the number of effective horizontal images is 720 pixels, and the aspect ratio is 16: 9. In order to obtain a square pixel without changing the number of effective scanning lines, it is sufficient that the number of pixels satisfies the following expression.

The number of pixels = 16/9 × 576 = 1024 In recording and transmitting image data, the amount of image data is enormous in an uncompressed state, and data compression is indispensable. In the case of using MPEG, one block of the discrete cosine transform (DCT) is 8 pixels × 8 pixels, and since the color difference information is generally a sample point of half the luminance, the number of pixels is a multiple of 16 1024 is a multiple of 16.

Therefore, if the number of horizontal effective pixels is set to 1024, each pixel becomes a square pixel, image processing by a computer can be easily performed, and image compression techniques such as JPEG and MPEG can be used. Then 4:
An apparatus for converting a signal of the 2: 2p (625) format into the signal format of the present invention will be described.

The 4: 2: 2p (625) system is a digital interface, and the luminance signal of the 625p analog signal has a sampling frequency of 27M as in the 525p system.
Hz, the color difference signal is sampled at 13.5 MHz, and video data of the 8: 4: 4 system is extracted in an interlaced manner for each line to form a set of interlace data, which is complementary to the extracted line. After dividing the related line as another interlace data, the line is extended twice on the time axis, and each of the lines is 13.5 MHz sampling 62 bits.
It interfaces with two bit streams having the same data structure as the 5-interlaced digital component signal.

Accordingly, the sampling frequency of the luminance data Y in the 4: 2: 2p (625) system is 27 MHz,
Color difference data C _B, the sampling frequency of the C _R 13.5
MHz. Therefore, the luminance data Y and the color difference data C
_B, and change the sampling rate of C _R to 64/45 times, it converts the number of effective horizontal pixels to 1024.

Hereinafter, an apparatus for converting a signal of the 4: 2: 2p (625) system into the signal format of the present invention will be described.
This will be described with reference to FIG. FIG. 2 is a block diagram of the present conversion device. 21 is a separation circuit. This separation circuit 2
1 4: 2: Data of 2p (625) system, is separated into luminance data Y, color difference data C _B, and color difference data C _R.

Reference numeral 22 denotes a first PLL circuit, which generates a clock signal of 1.728 GHz of a 64 times frequency synchronized with 27 MHz which is a sampling frequency of the luminance data Y. 23 ₁ is a second PLL circuit to generate a 64-fold frequency clock signal of 864MHz, which is synchronized with the 13.5MHz is the sampling frequency of color difference data C _B.

[0025] 23 ₂ is the third PLL circuit to generate a 864MHz clock signal of 64 times the frequency synchronized with the 13.5MHz is the sampling frequency of the color difference data C _R. 24 is a first interpolation / filter circuit.
The interpolation / filter circuit 24 inserts 63 0 data between the luminance data Y of each pixel based on the clock signal of 1.728 GHz from the PLL circuit 22. Then, harmonic components generated by the insertion are removed.
Further, the level of the interpolation / filter circuit 24 is lowered by inserting 0, so that a gain of 64 times is given.

Reference numeral 25 ₁ denotes a second interpolation / filter circuit. This interpolation / filter circuit 25 ₁
Based on the 864MHz clock signal from the inserts 63 zero data between the color difference data C _B of each pixel. Then, harmonic components generated by the insertion are removed. Furthermore, the level of the interpolation / filter circuit 25 ₁ is reduced by inserting 0, and therefore, a gain of 64 times is given.

[0027] 25 ₂ a third interpolation / filter circuit. The interpolation / filter circuit 25 _2, PLL circuit 22
63 data are inserted between the color difference data C _R of each pixel based on the 864 MHz clock signal from. Then, harmonic components generated by the insertion are removed. Furthermore, the interpolation / filter circuit 25 _2, the level is reduced by inserting the 0, giving a gain of 64 times.

Reference numeral 26 denotes a first frequency dividing circuit. The frequency dividing circuit 26 receives the 1.728 GHz clock signal from the PLL circuit 22 and divides the 1.728 GHz clock signal by 45 to generate a 38.4 MHz clock signal. 27 ₁ is a second frequency dividing circuit. The divider circuit 27 receives the clock signal of 864 MHz from the PLL circuit 23 _1, a clock signal of 864 MHz 4
The frequency is divided by 5 to generate a 19.2 MHz clock signal.

[0029] 27 ₂ is the second frequency divider. The divider circuit 27 receives the clock signal of 864MHz from the PLL circuit 23 ₂ generates a clock signal of 19.2MHz clock signal of 864MHz and circumferential 45 minutes. 28 is a first thinning circuit. This thinning circuit 2
8 thins out the interpolated luminance data Y based on the 38.4 MHz clock signal from the frequency dividing circuit 26.
Then, data having 1024 horizontal effective pixels is output.

Reference numeral 29 ₁ denotes a second thinning circuit. The thinning circuit 29 ₁ is configured to output 19.2 MHz from the frequency dividing circuit 27.
Color difference data C _B based on the clock signal of
Thin out. And the number of horizontal effective pixels is 1024/2
Output data. 29 ₂ is the third decimating circuit. This thinning circuit 29 ₂ is provided by the 1
Based on a clock signal of 9.2 MHz, it decimates the interpolated color difference data C _R. Then, data having 1024/2 horizontal effective pixels is output.

[0031] 30 is a digital compression encoder, horizontal effective pixels is 1024 luminance data Y and the number of horizontal effective pixels is 1024/2 pieces of color difference data C _B, and the horizontal effective pixel number 1024/2 pieces of color difference data Input C _R and digitally compress. Next, an apparatus for converting a 4: 2: 0p (625) signal into the signal format of the present invention will be described.

In the 4: 2: 0p (625) system, only the color difference signal of the video data of the 8: 4: 4 system described above is passed through a vertical low-pass filter, and then interlaced one by one in the vertical direction. This is a data method thinned out. Therefore, the luminance signal has 27 MHz sampling sequential scanning data, and the color difference signal has 6.75 MHz sampling data.

[0033] Thus, the above-described 4: 2: 0p (625) PLL circuit of converter in scheme 23 ₁ and the PLL circuit 23 ₂ is the sampling frequency of the color difference data 6.
A 432 MHz clock signal synchronized with 75 MHz may be generated. Hereinafter, the operation will be described with reference to FIG. 4: 2: 0p (625) data is input to the separation circuit 21, and the luminance data Y and the chrominance data C
It is separated into _B and the color difference data C _R.

The luminance data Y is supplied to the PLL circuit 22.
Is interpolated by the interpolation / filter circuit 24 on the basis of the 1.728 GHz clock signal generated in step (1) to remove a harmonic component. That is, the luminance data Y has 64 pixels.
This means that it has been converted to double the data. Also, the color difference data C
_B is based on the clock signal of 432MHz generated by the PLL circuit 23 _1, the interpolated by the interpolation / filter circuit 25 _1, the harmonic component is removed. That is,
Color difference data C _B would pixel number is converted to 64 times the data. Similarly, the color difference data C _R, based on the clock signal of 432MHz generated by the PLL circuit 23 _2, interpolated by the interpolation / filter circuit 25 _2,
Harmonic components are removed. That is, the color difference data C
_R means that the number of pixels has been converted to data of 64 times.

On the other hand, the 1.7 generated by the PLL circuit 22
The 28 GHz clock signal is divided by the frequency divider 26 into 45
Divided. Then, a clock signal of 38.4 MHz is generated. Further, the PLL circuit 23 ₁ and the PLL circuit 23
_The 432 MHz clock signal generated in ₂ is frequency-divided by the frequency dividing circuit 27 ₁ and the frequency dividing circuit 27 ₂ by 45. Then, a 9.6 MHz clock signal is generated.

The interpolated luminance data Y is supplied to a thinning circuit 2
8 decimates at 38.4 MHz samples. That is, 64 luminance data are thinned out to 45 luminance data, and 1024 samples of luminance data are output. Further, the interpolated color difference data C _B is the thinning circuit 29 _1, is thinned at 9.6MHz sample.
That is, the 64 pieces of color difference data are thinned out to 45 pieces of color difference data. Similarly, the interpolated color difference data C
_R is the decimation circuit 29 ₂ is thinned by 9.6MHz sample. That is, the 64 pieces of color difference data are thinned out to 45 pieces of color difference data. Then, 1024/2 sample data is output as the color difference data.

The digital compression encoder 30 digitally compresses 1024 samples of luminance data and 1024/2 samples of color difference data. In addition, FIG.
In the example of FIG. 3, Y, C _B and C
_A PLL circuit is provided for each _R.
2 in the example of FIG. 2 and 1 in the example of FIG.
It is possible to obtain clocks of 864 MHz and 432 MHz by dividing by / 4.

[0038]

According to the signal format of the image signal of the present invention, since each pixel is square at an aspect ratio of 16: 9, image processing by a computer can be easily performed.
Further, since the number of pixels in the vertical and horizontal directions is a multiple of 16, it is suitable for data compression such as JPEG and MPEG.

Further, it will be standardized in the future 4:
When converting a signal of the 2: 2p (625) system or 4: 2: 0p (625) system into the signal format of the present invention,
The conversion can be performed with a simple configuration without using a complicated rate converter.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a signal format of an image signal of the present invention.

FIG. 2 is a block diagram of a conversion device according to the present invention.

FIG. 3 is a block diagram of a conversion device according to the present invention.

FIG. 4 is a diagram for describing a standard of a component encoding method.

FIG. 5 is a diagram for explaining a video sequence.

FIG. 6 is a diagram for explaining a GOP.

FIG. 7 is a diagram for describing a picture.

FIG. 8 is a diagram for explaining a slice.

FIG. 9 is a diagram for explaining a macroblock.

FIG. 10 is a diagram for explaining blocks.

[Explanation of symbols]

Reference Signs List 21 separation circuit 22, 23 PLL circuit 24, 25 ₁ , 25 ₂ interpolation / filter circuit 26, 27 frequency dividing circuit 28, 29 ₁ , 29 ₂ thinning circuit 30 encoder

Claims (5)

[Claims] 1. A signal format of an image signal, wherein the number of effective scanning lines is 576 and the number of effective horizontal pixels is 1024. 2. A signal format of an image signal, wherein the aspect ratio is 16: 9 and the number of effective scanning lines is 576.
A signal format of an image signal, wherein the number of effective horizontal pixels is 1024. 3. A signal format of an image signal, wherein a sampling rate of luminance data in a progressively scanned image signal in which the number of effective scanning lines per field is 576 and the number of horizontal effective pixels is 720 is 64/45. A method of converting the format of an image signal, comprising converting the image data into a progressively scanned image signal having 1024 effective horizontal pixels. 4. An apparatus for converting a signal format of an image signal, comprising: a luminance data of a progressively scanned image signal having 576 effective scanning lines per field and 720 horizontal effective pixels. An image signal format converter comprising means for converting a sampling rate to 64/45 times and converting it into a progressively scanned image signal having 1024 effective horizontal pixels. 5. The number of effective scanning lines per field is five.
An apparatus for converting the format of a progressively scanned image signal having 76 lines and 720 horizontal effective pixels, comprising: a first clock signal having a frequency 64 times a sampling frequency of luminance data in the progressively scanned image signal. Means for inserting zero data into luminance data of the progressively scanned image signal based on the first clock signal, and applying a low-pass filter; and means for dividing the first clock signal by 45. 1 frequency dividing means; means for thinning out luminance data into which zero data has been inserted based on the clock signal divided by the first frequency dividing means; sampling frequency of color difference data in the progressively scanned image signal Means for generating a second clock signal having a frequency 64 times the frequency of the second clock signal; and zero data in the color difference data based on the second clock signal. Means for inserting and applying a low-pass filter; second frequency dividing means for dividing the second clock signal by 45; and zero data based on the clock signal divided by the second frequency dividing means. Means for thinning out the inserted color difference data.