JP2003158720A - Image recorder and image reproducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the image quality at the time of encoding/decoding in recording or reproducing a digital image. SOLUTION: The image recorder has a standard mode for inputting the digital image to be input as it is and encoding and a long time mode for inputting the digital image of thinned-out pixels and encoding in recording the digital image. In the case of decoding, the image recorder outputs the image data recorded in the standard mode as the decoded image data as it is, and outputs the image data recorded in the long time mode to interpolate the thinned-out pixels after decoding. This image recorder uses the two different recoding methods having the standard mode and the long time mode to provide the user's convenience, to enhance the compression, thereby recording and reproducing with little deterioration of the image quality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to compression encoding and decoding of moving images.

[0002]

2. Description of the Related Art M is a well-known compression encoding method for moving images.
PEG (ISO / IEC11172 (MPEG1), I
As represented by SO / IEC13818 (MPEG2), DCT (Discrete Cosine Tr)
compression coding is performed by using the (amplification) and the quantization.

By the way, human visual characteristics are insensitive to the high frequency side.

For this reason, for example, in MPEG1, the amount of data is efficiently reduced by halving the high frequency component of the input image data and greatly blurring the image quality, and then thinning out the pixels.

On the decoding side, the image data obtained by decoding is interpolated and interpolated to restore the image. In this method, the frequency component in the horizontal direction is attenuated by half, so the image quality deteriorates, but the degree of image quality deterioration is small relative to the compression efficiency.

[0006]

As described above, the compression efficiency and the image quality level conflict with each other.

The present invention has been made in view of such a problem in an image recording / reproducing apparatus for recording and reproducing a digital image, and improves the compression efficiency of the image by thinning processing and , Can be selectively set.

[0008]

SUMMARY OF THE INVENTION According to the present invention, thinning means for thinning input digital image data to reduce the number of pixels to be transmitted, and pixels which are the output of the input digital image data and the thinning means. A selection means for selecting any one of a small number of image data; an encoding means for encoding an output of the selection means; and a mode information encoding means for encoding information on a selection mode of the selection means. Is characterized by.

The present invention, in an image recording apparatus for recording input digital image data on a recording medium according to the standard mode or the long time mode, thins out the input digital image data to reduce the number of transmission pixels. Means, selecting means for selecting either the input digital image data or the image data with a small number of pixels which is the output of the thinning means, an encoding means for encoding the output of the selecting means, and the selection mode. Standard information encoding means for encoding information about the information, and a recording means for recording the code string output from the encoding means and the mode information output from the mode information encoding means on a recording medium. In the mode, the selecting means is controlled so that the input digital image data is inputted to the encoding means without passing through the thinning means, and the input is performed for a long time. At the time of reading, the selection means is controlled so that the image data having a small number of pixels, which is obtained by thinning the input digital image data by the thinning means, is input to the encoding means, It is characterized in that the code string which is the output and the mode information which is the output of the mode information encoding means are recorded on the recording medium by the recording means.

The present invention is characterized by comprising mode information adding means for inserting the output of the mode information encoding means into a predetermined position of the code string which is the output of the encoding means.

According to the present invention, the encoding means performs encoding for managing a plurality of image data as a set with motion compensation, and the mode information adding means is for each management image data cycle. The information about the selection mode is inserted at least once.

The present invention is characterized in that the thinning means is thinning processing by subsampling.

The present invention is characterized in that the thinning means is a thinning process by dropping frames in the time direction.

According to the present invention, a decoding means for recovering image data from a code string in an image reproducing apparatus for reproducing a moving image by inputting a code string corresponding to at least two different modes and information about the mode of the code string. And an interpolating unit that performs an interpolating process by using the restored image data as an input, and a selecting unit that selects and outputs either the output of the decoding unit or the output of the interpolating unit according to information about the mode. Is characterized by.

According to the present invention, a code string of encoded digital image data and mode information indicating whether the digital image data is recorded in the standard mode or the long time mode are provided. In an image reproducing device for reproducing a recorded recording medium, a mode information extracting unit for extracting the mode information, a decoding unit for restoring image data from the code string, and an interpolation process using the restored image data as an input. It is characterized by further comprising: an interpolating means for performing, and a selecting means for selecting and outputting either the output of the decoding means or the output of the interpolating means according to the mode information extracted by the mode information extracting means. .

[Operation] The present invention has two recording modes, the standard mode and the long time mode, and controls the presence / absence of thinning processing at the time of encoding and the presence / absence of interpolation processing at the time of decoding according to this mode. .

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG.

FIG. 1 is a block diagram of a moving picture coding apparatus.

Reference numeral 11 is a thinning means. This thinning-out means 1
1 reduces the number of transmission pixels by the thinning process. It should be noted that a band limiting filter for removing interference such as aliasing due to thinning is provided as necessary.

Reference numeral 12 is a selection means. Selecting means 12
Selectively outputs the input image data or the transmission pixel data obtained by thinning the input image data. This selection means 12
Are switched and controlled according to the compression mode. When the compression mode is the normal mode, the input image data is output. When the compression mode is the high compression mode, the thinning means 11 outputs the image data in which the number of transmission pixels is reduced.

Reference numeral 13 is a compression encoding means. The compression encoding unit 13 receives the image data selected by the selection unit 12 as input, performs encoding, and outputs an encoded string.
The compression encoding means 13 compresses the digital moving image into a predetermined data amount to generate an encoded string. For example, MPEG, MPEG2, Motion JPEG,
A compression coding method by orthogonal transformation and quantization such as H261 or a quantization that reduces the code amount by directly changing the quantization step corresponding to the dynamic range of pixel values without using orthogonal transformation The encoding may be performed by a compression encoding means or the like to reduce the code amount after encoding to create a code string having a constant transmission rate.

That is, the compression encoding means 13 outputs a decodable code string for the input image data with a predetermined data amount smaller than the input data amount.

The compression coding means 13 forms a first compression coding means (13) for coding the input digital image data and generating a first code string.

Further, the thinning means 11 and the selecting means 13 carry out thinning processing on the input digital image data to reduce the number of transmission pixels and perform coding to generate a second code string. Of the code generation means (11, 13).

The selecting means 12 selects the generation of the first code string or the second code string.

First, regarding the thinning processing of the thinning means 11,
explain.

As described above, the thinning-out means 11 is a means for reducing the number of transmission pixels by the thinning-out processing, and is provided with a band limiting filter for removing the aliasing distortion caused by the thinning-out.

As the thinning-out processing, for example, there is a thinning-out method by intra-field sub-sampling as shown in FIG.

The fields F1, F2 and F3 are three fields which are temporally continuous and are composed of blocks B1, B2 and B3.
Is a region (3 × 3) cut out from the regions of the fields F1, F2, and F3 at the same spatial position, and “x” indicates a non-transmission pixel by thinning.

It is possible to reduce the number of transmission pixels to 1/2 by using the same pattern in the form of a grid of 5 for each field.
By performing interpolation during reproduction, a reproduced image having a relatively high resolution can be obtained.

FIG. 8 is an example of another thinning pattern.

In an interlaced image (current TV broadcast, NTSC, PAL, etc.), the vertical positions of two fields (odd field and even field) are different,
5 in the frame plane composed of 2 fields
This is an example of thinning out by sub-sampling in a grid pattern.

Fields G1, G2, G3, G4 represent four temporally consecutive fields.

The block C1 is composed of two consecutive fields G1 and G2, and the block C2 is composed of two consecutive fields G3 and G4. Is extracted, and the transmission pixel in the even field is shown as □. In addition, the transmission pixel in the odd field is shown as ◯. Further, non-transmission pixels are shown as x.

In this way, the number of transmission pixels is reduced to 1/2 with the same pattern in the form of a grid of 5 for each frame.

Further, in a system provided with a method of encoding an interlaced signal in frame units such as MPEG2, it is possible to perform encoding in the same thinned screen unit, and image quality deterioration due to thinning out occurs. Less is.

FIG. 9 shows an example of thinning out by sub-sampling in frame units.

By alternately setting the phases of the transmission pixels on a frame-by-frame basis, it is possible to transmit pixels at all positions in four fields.

If the reproduction is performed by interpolation using four fields, the resolution in the still region is excellent, but blurring occurs in the moving image region.

The thinning method by subsampling has been described above. It should be noted that the present application is not limited to any thinning-out means, and it is possible to reduce the number of transmission pixels by changing the sampling frequency in the horizontal or vertical direction, reduce the number of transmission pixels in the time direction such as frame dropping, and the like. It is possible to use any thinning means for the purpose of reducing the number.

In the above description, the thinning process
Although it is described that the number of transmission pixels is reduced to 1/2, the reduction ratio of pixels is not limited. That is, any ratio may be used as long as the number of transmission pixels is reduced by thinning.

The operation of FIG. 1 will be described.

The input image data is input to the thinning means 11 and the number of transmission pixels is reduced to, for example, 1/2 by thinning processing.

The selecting means 12 receives the input image data or the thinning means 1 according to the compression mode designated from the outside.
One of the image data having a small number of transmission pixels, which is the output of 1, is selectively output. That is, the selecting means 12 selectively outputs the input image data when the compression mode is the normal mode.
When the compression mode is the high compression mode, the selection unit 12 selects and outputs the image data in which the number of pixels transmitted by the thinning unit 11 is reduced.

The compression encoding means 13 receives the image data selected by the selection means 12 as input, controls the predetermined amount of data according to the compression mode, and outputs a code string. At this time, in the high compression mode, the amount of data is controlled to be as small as 1/2 or 1/3 of the normal mode.

By using a thinning means having a good reproduction image quality, a high compression mode with less deterioration becomes possible.

A second embodiment of the present invention will be described with reference to FIG.

FIG. 2 shows a moving picture coding apparatus.

In FIG. 2, the same parts as those in FIG.

The second embodiment is obtained by adding mode information coding means 14 and addition means 15 to the first embodiment of FIG.

The mode information coding means 14 generates a specific code string corresponding to the compression mode.

The adding means 15 inserts the code string from the mode information coding means 14 into a specific position of the output of the compression coding means 13.

For example, if the compression encoding means 13 is MPEG1 or MPEG2 encoding, the adding means 15 inserts the additional code indicating the compression mode into the user data area existing in various header information. ing. Also, a plurality of images such as MPEG2 can be combined into one group (G
In the compression encoding method for performing encoding as OP), the minimum unit for switching the compression mode is the GOP unit and at least 1 G since the reproduction in the GOP unit can be compensated.
An additional code indicating the compression mode is inserted once into OP.

The mode information coding means 14 and the addition means 15 code the selected mode of the selection means (12) and insert it at a predetermined position of the code string. Is formed.

As described above, in the second embodiment, the code string indicating the compression mode is added in the code string of the image data.

Since the code indicating the compressed mode in the normal mode does not matter whether it is inserted or not,
It is no exception to add a code indicating the high compression mode only in the high compression mode.

Although the compression mode switching unit is described above by taking MPEG2 as an example, the compression mode may be switched at any time as long as it is a reproducible unit.

Further, the position and the cycle at which the code string indicating the compression mode is inserted have been described above by taking MPEG2 as an example, but any position and cycle can be used as long as the position and the cycle are separable and do not hinder the reproduction. May be.

A third embodiment of the present invention will be described with reference to FIG.

FIG. 3 is a block diagram of the moving picture decoding apparatus.

The third embodiment is an apparatus for returning the data encoded in the first embodiment to the original moving picture.

Reference numeral 21 is a decoding means. The decoding means 21 generates transmission pixel data from the input code string.

Reference numeral 22 is an interpolating means. Interpolation means 22
If the compression mode is the high compression mode, the non-transmission pixel data is calculated by the interpolation process and arranged at a predetermined position.
As a result, the image data has the same screen size as the output of the decoding means 21 in the normal mode.

Reference numeral 23 is an output selecting means. The output selection means 23, according to the compression mode given at the same time,
In the normal mode, the output of the decoding means 21 is selected and output as reproduced image data. In the high compression mode, the output of the interpolation means 22 is selected and output as reproduced image data.

In the third embodiment, the output selection means 2
3 is provided after the interpolating means 22. However, for example, by using an interpolating unit that allows an input signal to pass through in the normal mode and interpolates in the high compression mode, the output selecting unit 23 and the interpolating unit 22 can be integrated.

The decoding means 21 of the third embodiment forms the first reproduction means (21) which restores the image data from the input code string and makes it the first reproduction image.

The decoding means 21 and the interpolating means 22 restore the image data from the input code string and perform the interpolation processing on the restored image data to make the second reproduced image the second generating means (21, 22). ) Is formed.

The output selecting means 23 forms a selecting means (23) for selecting and outputting either the first reproduced image or the second reproduced image according to the mode.

A fourth embodiment of the present invention will be described with reference to FIG.

FIG. 4 is a block diagram of the moving picture decoding apparatus.

The fourth embodiment is an apparatus for returning the data coded in the second embodiment to the original moving picture.

In the fourth embodiment, the code string in which the code string indicating the compression mode is added to the code string of the image data is decoded.

That is, in the fourth embodiment, the moving picture coding apparatus of the third embodiment is further provided with the code separating means 24.

The code separating means 24 separates the code string indicating the compression mode from the input code string and distributes the compression mode signal to all the blocks that require it.

A fifth embodiment of the present invention will be described with reference to FIG.

FIG. 5 is a block diagram of the moving image recording apparatus.

In the fifth embodiment, a moving picture recording apparatus is constructed by using the moving picture coding apparatus of the first embodiment.

Here, the compression mode is referred to as a recording mode because it relates to the recording time for recording a moving image.

That is, the normal mode corresponds to the standard mode. The high compression mode corresponds to the long time recording mode.

The code string output from the moving picture coding device 30 is multiplexed with the recording mode signal by the multiplexing means 31 and, at the same time, converted into a signal format suitable for the recording medium 33.

Then, the data is written in the recording medium 33 via the recording medium writing means 32.

The multiplexing with the recording mode signal in the multiplexing means 31 is not to be inserted at a specific position of the code string of the image data but to be multiplexed at a position designated according to the signal format recorded on the recording medium 33. is there.

If the recording medium has a data area for recording and managing the recording mode for each data in the recording medium, the mode information is recorded in the data area of the same recording medium. May be.

A sixth embodiment of the present invention will be described with reference to FIG.

FIG. 5 is a block diagram of the moving image recording apparatus.

In the sixth embodiment, a moving picture recording apparatus is constructed by using the moving picture coding apparatus of the second embodiment.

The recording mode signal is already coded and inserted in the code string output from the moving picture decoding apparatus 34.

Therefore, after the recording medium writing means 35 converts the code string into a signal format suitable for the recording medium,
Write to the recording medium 33.

[0089]

According to the present invention, the thinning process can be selectively performed according to the mode at the time of encoding, so that the compression rate can be increased and the convenience of encoding with less deterioration of image quality can be achieved. Will increase. Further, the code string encoded in this way can be accurately decoded.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a moving picture coding apparatus according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a moving image encoding device according to a second embodiment.

FIG. 3 is a configuration diagram of a moving picture decoding apparatus according to a third embodiment.

FIG. 4 is a configuration diagram of a moving picture decoding apparatus according to a fourth embodiment.

FIG. 5 is a diagram showing a fifth embodiment.

FIG. 6 is a diagram showing a sixth embodiment.

FIG. 7 is a diagram for explaining thinning means.

FIG. 8 is a diagram for explaining thinning means.

FIG. 9 is a diagram for explaining thinning means.

[Explanation of symbols]

11 thinning means 12 Selection means 13 compression encoding means (encoding means) 14 Mode information coding means (mode information addition means) 15 Addition means (mode information addition means) 21 Decoding means 22 Interpolation means 23 Output selection means (selection means) 24 Code Separating Means (Mode Information Separating Means) 30 Video coding device 31 Multiple means 32 recording medium writing means 33 recording media 34 Moving picture coding device 35 recording medium writing means

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Minaki Taoka             2-5-3 Keihan Hondori, Moriguchi City, Osaka Prefecture             Yo Denki Co., Ltd. F-term (reference) 5C053 FA02 FA03 GA11 GB17 GB19                       GB21 HA40 JA22                 5C059 LB05 LB07 LB15 LB18 MA00                       MA23 MC11 PP04 RC24 SS11                       TA06 TA07 TA08 TB01 TC18                       TC39 UA02 UA05                 5D044 AB07 DE12 GK08

Claims (8)

[Claims] 1. A thinning means for thinning the input digital image data to reduce the number of transmission pixels, and either the input digital image data or the image data with a small number of pixels which is the output of the thinning means. An image recording apparatus comprising: a selection unit that selects a selection unit, a coding unit that codes an output of the selection unit, and a mode information coding unit that codes information regarding a selection mode of the selection unit. 2. An image recording device for recording input digital image data on a recording medium according to a standard mode or a long time mode, and a thinning means for thinning the input digital image data to reduce the number of transmission pixels. Selection means for selecting either the input digital image data or the image data with a small number of pixels output from the thinning means, an encoding means for encoding the output of the selection means, and information on the selection mode Mode information encoding means for encoding, and a recording means for recording the code string output from the encoding means and the mode information output from the mode information encoding means on a recording medium. In this case, the selecting means is controlled so that the input digital image data is inputted to the encoding means without passing through the thinning means, and the long time mode is set. In this case, the selecting means is controlled so that the image data having a small number of pixels, which is obtained by thinning the input digital image data by the thinning means, is input to the encoding means, and the output of the encoding means is used. An image recording apparatus, wherein a certain code string and mode information output from the mode information encoding means are recorded on a recording medium by a recording means. 3. The image recording according to claim 2, further comprising: mode information adding means for inserting an output of the mode information encoding means into a predetermined position of a code string which is an output of the encoding means. apparatus. 4. The encoding means according to claim 3,
Encoding for managing a plurality of image data as a set with motion compensation, wherein the mode information adding means inserts information on the selected mode at least once for each management image data cycle. An image recording device characterized by. 5. The image recording apparatus according to claim 2, wherein the thinning means is thinning processing by subsampling. 6. The image recording apparatus according to claim 2, wherein the thinning means is thinning processing by dropping frames in a time direction. 7. An image reproducing device for reproducing a moving image by inputting a code string corresponding to at least two different modes and information about a mode of the code string, and a decoding means for restoring image data from the code string, It is provided with an interpolating unit that performs an interpolating process using the restored image data as an input, and a selecting unit that selects and outputs either the output of the decoding unit or the output of the interpolating unit according to the information about the mode. Image reproduction device. 8. A code string of encoded digital image data and mode information indicating whether the digital image data is recorded in a standard mode or a long time mode are recorded. In an image reproducing apparatus for reproducing a recording medium, a mode information extracting unit for extracting the mode information, a decoding unit for restoring image data from the code string, and an interpolation process for receiving the restored image data as an input. Image reproduction, characterized in that it comprises: means and selection means for selecting and outputting either the output of the decoding means or the output of the interpolation means in accordance with the mode information extracted by the mode information extraction means. apparatus.