JPH07203429A - Image processing method and its device - Google Patents

Abstract

PURPOSE:To generate plural codes whose code quantity differs with simple configuration by converting plural data having correlation into a 1st code quantity whose capacity is available of transmission to a medium and converting the 1st code into a 2nd code quantity with a smaller code quantity without decoding. CONSTITUTION:A dynamic image input section 10 digitizes a video image from a video camera or the like and gives the digitized image to a 1st coding section 11, in which 1st coding with high image quality for the recording to a digital tape or a digital disk is implemented while selecting a parameter at a comparatively low compression rate for irreversible coding. The resulting data are fed to a recording control section 17 and stored on a disk 18. On the other hand, a 2nd coding section 12 generates 2nd coding data with less data quantity by replacing part of the 1st coding data. The 2nd coding data are fed to a reception section 14 through a communication line from a transmission control section 13 and decoded by a decoding section 15 and displayed on a display section 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing method and apparatus, and more particularly to an encoding processing method and apparatus.

[0002]

2. Description of the Related Art For example, in a system for recording an image from a video camera on a digital video device or the like while monitoring it at a distance through a communication line, the video recording is
An encoding method with higher image quality, on the other hand, a monitor is desired to have an encoding method in which the amount of data to be communicated is small even if the image quality is sacrificed.

However, in the conventional moving picture coding system, since the purpose is to create one kind of code having a constant rate, coded data having a high compression rate enough to pass through a communication line is generated and used for communication / communications. The first method of accumulation was taken.

As a second method different from the first method, there is a method in which respective dedicated encoders are provided in parallel for communication and storage to generate different codes.

[0005]

However, in the above-mentioned conventional example, a communication line having a communication capacity equal to or higher than the transfer speed to the digital recording device is required, and the usable line is limited or the image quality is accumulated. There was a problem such as restricting communication.

In the second method, it is necessary to prepare two types of encoders having the same scale, which causes a problem that the device becomes complicated.

It is an object of the present invention to solve the problems of the present invention and to allow a plurality of codes having different code amounts to be generated by a simple method or configuration.

[0008]

In order to achieve such an object, the first invention of the present application converts a plurality of data having correlation with each other into a first code amount which can be transmitted to a medium by a first encoding method. An image processing method for converting the obtained code of the first code amount into a second code amount which is smaller than the first code amount and can be transmitted to a medium without decoding. A second invention is a first coding means for converting a plurality of data having a correlation with each other into a first code amount which can be transmitted to a medium by the first coding method, and the obtained code of the first code amount is The image processing apparatus has a second encoding unit that converts the second code amount to a second code amount that is smaller than the first code amount and can be transmitted to a medium without decoding.

[0009]

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

The moving image input section (10) digitizes the image from the video camera or the like and sends it to the first encoding section (11). Here, the first coded data of high image quality for recording on a digital tape or a disk, that is, a parameter having a relatively low compression rate in lossy coding is selected and coded. Examples of such encoding include the MPEG system and the like. This data is sent to the recording controller (17) and stored in the disc (18).

On the other hand, in the second encoding unit (12), a second encoded data having a small data amount is created by replacing a part of the first encoded data by a method described later. This data is sent from the transmission control unit (13) to the reception unit (14) through the communication line, and the decoding unit (1
It is decrypted in 5) and displayed on the display unit (16).

FIG. 3 is a block diagram of the first encoding unit 11.

The coding mode determiner (30) gives an instruction as to whether intra-frame coding or inter-frame coding will be performed as described later. In the difference generator (31), the difference between the encoded frame and the encoded image is taken in the interframe coding mode, and the original image data is output without taking the difference in the intraframe coding mode. Next, the output data is converted into a frequency component by the orthogonal transformer (32), and the quantizer (33)
Then, each frequency component is quantized by a predetermined quantization table. Next, this component data is sent to the variable length encoder (3
4) is encoded. The code amount monitor unit (35) determines the quantization step so that the code amount is constant rate, that is, the code amount per unit time is constant, based on the amount of codes output from the variable length encoder 34. Send to the quantizer (33). The decoder (37) decodes the exit of the encoder 34 to generate the image data obtained on the reproducing side, and records this in the frame memory (36). When determining the quantization step, the quantization step of the quantizer 33 for the frame following the previous frame is determined based on the code amount of the previous frame. Motion vector detector (3
In 7), when the difference between the pixel block of the reference frame and the pixel block of the coding frame is calculated, a vector to the pixel block of the coding frame with respect to the pixel block of the reference frame is detected. The position vector that minimizes is detected. The vector data is encoded by the variable length encoder.

FIG. 4 is an explanatory diagram of three types of coding modes used in one embodiment of the present invention.

The first coding mode is an intra-frame coding mode (described later as I).

The second coding mode is the forward prediction mode (described later as P). In this method, a previously encoded frame is referenced, a motion vector is detected, motion compensation is performed, a difference between frames is calculated, and this is encoded.

The third coding mode is the bidirectional prediction mode (described later as B). In this method, two encoded frames before and after are referred to, motion compensation is performed on each of the encoded frames, the difference is encoded, and one having a smaller code amount is selected.

By the way, in the P and B coding modes, when constructing a copy command that creates the same as the previous frame, the motion vector and the code indicating that the interframe difference is 0 are collected and output. It can be easily configured.

FIG. 5 is an explanatory diagram showing an example of the frame number, frame structure and coding order of the moving image data after being coded according to the structure of FIG. In this example, I is used for the images of frame numbers 1, 5, 9, ... And the images to be coded using P by referring to the images of the frame numbers are designated as frame numbers 3, 7 ,. Use B for frame numbers 2, 4, 6, 8 ...

FIG. 6 is an explanatory diagram of coded data (bit stream) obtained from the apparatus of one embodiment of the present invention.

(1) is the first encoded data obtained from the first encoding unit 11 in FIG. Following the sequence header in which the image size, the number of frames per second, etc. are described, the I, P, and B frame headers and the code data are continuously output as shown in the figure.

(2) is B by the second encoder of FIG.
6 (1) is replaced with a copy instruction.

The replacement process with such a copy code is a very simple process with few operations, and the code of the copy instruction is very short. Therefore, the second encoding unit 12 obtains the encoded data amount by a simple process. It can be greatly reduced. However, in the sequence header, the first encoding unit 11 describes that the data is N frames per second, but the frame encoded by the above B is a copy of the previous frame. As a result, the motion of the image is reproduced at a rate of N / 2 frames per second. This ratio becomes lower as the number of frames coded by B described above increases.

Further, by replacing both the images coded by either the P or B coding method by the second coding unit with the copy command, the code amount is further increased as shown in FIG.
It can be reduced as shown in (3). However, the motion of the image is reproduced at a rate of N / 4 frames per second.

According to such an embodiment of the present invention, FIG.
(2) In addition to reducing communication data as shown in (3),
For example, when the moving image coded data provided by the computer is decoded / displayed by software instead of decoding hardware, such processing is simplified.

That is, since the above-mentioned copy instruction has a short code, it can be detected by executing the code matching instruction when it is combined with the above-mentioned software. Based on such detection, the copy instruction detected without performing the actual image data copy processing operation can be replaced by the freeze instruction of the previous frame by software.

On the other hand, in the case of processing by hardware as described above, it is easier to directly execute the copy instruction without performing another processing such as detecting the copy instruction by code matching and replacing it with a freeze instruction. is there.

That is, the encoded data of the present embodiment has the effect of simplifying the decoding process in both the software decoding process and the hardware decoding process. Therefore, the coded data of this embodiment has the effect of requiring a minimum change when the data processed by software at the time of system introduction is updated to the processing by hardware at a later date.

[Second Embodiment] A communication line used for transmitting encoded data is not a fixed rate line such as a circuit switching system but a variable rate line such as a local area network. While monitoring the degree of network congestion, for example, (1) in FIG. 6 described above.
(2) It is also possible to control the code amount to be communicated by selecting any one of (3).

That is, if the network seems to be free, the frequency of the process of replacing with the copy instruction is reduced, and if it seems to be congested, the frequency of the replacement with the copy instruction is frequently performed.

[Third Embodiment] In the above-described embodiments, the sequence headers assigned to the codes output from the first encoding unit and the second encoding unit are common, but the first embodiment is common. Even if the encoded data of each fixed frame number is configured by using the sequence header in which the number of frames of each second is described separately for the encoded data output from the encoding unit and the second encoding unit, respectively. Good.

To this end, the code encoded with B is removed from the first encoded data without replacing the P and B frames with the copy instruction, and the data encoded with I and P described above is removed. A code that is composed only of data is generated, or a code that is composed only of data coded by I is generated.

[Third Embodiment] For example, as shown in FIG. 2, the present invention is applied to the case where one video source is sent through a plurality of data lines A, B, and C having different transfer rates, though the numbers are changed. can do.

That is, as shown in FIG. 7, the second encoding unit (7
0-1, 70-2, 70-3) is prepared for the line,
The control unit 700 is provided so that any one of those shown in FIGS. 6 (1), (2), and (3) can be independently selected, and the outlets of the second encoding units 70-1, 70-2, and 70-3 are provided. It transmits through the communication control part (71-1, 71-2, 71-3).

As described above, according to this embodiment,
For example, moving images from a video camera through a communication line,
In a system for recording on a video disc or the like while monitoring at a distance, video recording can be performed with high image quality, while the amount of data sent to the monitor can be reduced.

The present invention is not limited to the coding methods shown in I, P and B shown in FIG. 4, but can be applied to other methods, such as a coding method in which all screens are intra-frame coded. .

The present invention is not limited to moving image data, but can be applied to a plurality of data having correlation with each other, for example, data having a plurality of still image data having correlation with each other.

Further, the present invention is not limited to the communication line and the monitor as described above, but can be similarly applied as long as it is transmitted to various other media.

[0039]

According to the present invention, a plurality of codes having different code amounts can be generated with a simple method or configuration.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a block diagram of a second embodiment of the present invention, that is, an embodiment when transmitting through a plurality of lines.

FIG. 3 is a block diagram of an encoder.

FIG. 4 is an explanatory diagram of an encoding mode.

FIG. 5 is an explanatory diagram of a frame configuration.

FIG. 6 is an explanatory diagram of encoded data.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location H04B 1/66 9372-5K H04N 5/92 H04N 5/92 H

Claims (9)

[Claims] 1. A plurality of mutually correlated data are converted into a first code amount that can be transmitted to a medium by a first encoding method, and the obtained code having the first code amount is decoded without decoding. An image processing method characterized by converting to a second code amount which is smaller than the first code amount and can be transmitted to a medium. 2. The image processing method according to claim 1, wherein a specific code among the codes having the first code quantity is converted into the second code quantity by replacing with a copy code. 3. The image processing method according to claim 1, wherein only a predetermined code among the codes having the first code amount is selected to convert the code into the second code amount. 4. The image processing method according to claim 1, wherein the plurality of pieces of data having correlation with each other are adjacent frame images of moving image data. 5. The image processing method according to claim 1, wherein the medium is a communication line or a storage unit. 6. A first encoding means for converting a plurality of mutually correlated data into a first code amount that can be transmitted to a medium by a first encoding method, and decoding the obtained code of the first code amount. An image processing apparatus comprising: a second encoding unit that converts into a second code amount that is smaller than the first code amount and that can be transmitted to a medium without performing the above. 7. The second encoding means converts the code having the first code amount into the second code amount by replacing a specific code with a copy code. Item 6. The image processing device according to item 6. 8. The second encoding means converts to the second code amount by selecting only a predetermined code from the codes of the first code amount.
Image processing device. 9. The image processing apparatus according to claim 6, wherein the plurality of pieces of data correlated with each other are adjacent frame images of moving image data.