JPH0228949B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of transmitting image information such as still images to a remote location.
It can be used in video information systems such as telemetering and surveillance systems.

Configuration of Conventional Example and Its Problems FIG. 1 shows an example of the configuration of a device embodying a conventional method for encoding and transmitting image information such as still images. 1 is an input/output unit for image information, A/D, D/
It consists of A converter etc. Reference numeral 2 denotes an image memory section, which is composed of memory such as RAM for one screen. Reference numeral 3 denotes an encoding unit, which is composed of a circuit that realizes encoding and decoding that removes redundancy included in image information and reduces the amount of information to be transmitted. Reference numeral 4 denotes a transmission section, which is composed of a transmitting and receiving circuit for transmitting encoded image information to a remote location. Reference numeral 5 denotes a control section which controls input and output of each section, and is composed of a logic circuit such as a microcomputer.

Input image information includes still image signals from cameras, color (R, G, B) from tablets, etc.
There are traffic lights etc. As an example, a case will be described in which a color still image signal from a camera is input as red (R), green (G), and blue (B) component signals, encoded, and transmitted. The R, G, and B component signals inputted from the input/output section 1 are stored in the memory section 2 for one screen. FIG. 2 shows the configuration of the screen memory. R.G.
Each B frame memory has 1 line and P dot pixels for each of the R, G, and B components, and each pixel is composed of m bits.

As the encoding method of the encoding unit 3, a predictive coding (DPCM) method is often used. The DPCM encoding circuit is shown in FIG. 3, and the decoding circuit is shown in FIG. 4. 11 is a quantizer, 12 is a predictor, 13 is a subtracter, and 14 is an adder. In the encoding circuit shown in FIG. 3, a predictor 1 predicts an input m-bit image signal x _i based on the previous input signals.
The subtracter 13 subtracts the two values x _i ^ to obtain a difference signal component, which is quantized by the quantizer 11 and converted to an n-bit signal t _i (n<m) to reduce redundancy and improve transmission efficiency. is increasing. t _i and x _i ^ are the adder 14
and used to predict the next image signal x _j (j>i). Prediction is performed using the signal values of a plurality of dots a plurality of lines before. An example of a prediction formula is shown in FIG. Here, in order to predict x _i , the prediction is performed using the signal A from one line before and the signal B from one dot before, which are the closest. In the decoding, as shown in FIG. 4, x _{i ^} is obtained and decoded using the same predictor 12 as the encoding circuit based on the input signal ti.

The signal encoded by the encoder 3 is sent to the transmitter 4 as a simple code sequence shown in FIG. 6 under the timing control of the controller 5, and the transmitter blocks it for transmission and performs error protection. , the encoded data is constructed in units of one frame, and a frame header pattern is attached to the beginning of the encoded data for transmission.

Generally, the information amounts of the R, G, and B components of a still image signal from a camera are not the same, and the G component is the largest and the other components are small. Therefore, when predictive coding is performed, transmission efficiency can be improved by maximizing the number of quantized bits n _G of the G component and decreasing the number of bits n _R and n _B of the other components. On the other hand, when performing predictive encoding on input signals from tablets, etc.,
Since the R, G, and B components have the same amount of information, the same number of quantization bits is sufficient, but the prediction formula and quantizer may be different from those for still image signals. In order to change the type of signal to be transmitted or to improve transmission efficiency as described above, it is necessary to include information on various encoding parameters in the encoded sequence.

On the other hand, in the predictive coding method, as shown in FIG. 5, the values of the previous line and previous dot are used to predict one point. Therefore, when the image signal having the configuration shown in FIG. 2 is encoded, the prediction accuracy of the first line and the first dot becomes poor.

Purpose of the Invention The present invention provides an encoding method that can change encoding parameters such as the number of lines constituting a screen, the number of dots constituting each line, and the number of quantization bits for encoding for multiple types of input signal sources. The present invention provides a transmission method and also provides a method for increasing the prediction accuracy of the first line or dot of an image in a predictive coding method.

Structure of the Invention The present invention adds frame configuration information and line configuration information between the conventional frame header pattern and the encoded data as a code sequence for transmitting encoded information, thereby indicating the frame type. It consists of frame identification, line information representing information such as the number of lines composing the frame, dot information representing information such as the number of dots composing each line, encoding information representing parameters of the predictive encoding method, etc. information is added before the encoded data of each image line, and a line identification code for line identification,
It consists of a line count, etc. that represents the count value of the number of lines.

DESCRIPTION OF THE EMBODIMENTS The structure of the transmission code sequence is shown in FIG. As shown in FIG. 7a, the code sequence is composed of a conventional frame header pattern, frame structure information of the present invention, line structure information, and encoded data. When the information is composed of R, G, and B color components like still image information, each frame of R, G, and B is composed. The structure of the frame structure information is shown in FIG. 7b. The frame identification information is used to identify the frame and indicate the frame type such as R, G, B, etc. Line information represents information such as the number of lines that make up a frame. The dot information represents information on dot numbers forming the line. The encoding information represents information such as the number n of quantization bits of the predictive encoding method. The structure of the line configuration information is shown in FIG. 7c. The first line identification code is a specific pattern for each line identification. Line count is used to represent the line information number. In the conventional configuration shown in FIG. 1, the control unit 5 handles the frame configuration information, line configuration information, etc. of these encoded transmission systems.

When encoding the R, G, and B components of a still image signal by changing the number of quantization bits for each component,
The values of each quantization bit number n _R , n _G , n _B are R, G,
It is expressed as a value of encoded information of frame configuration information of each frame of B.

In addition, when transmitting still images with different resolutions, that is, still images with different numbers of lines constituting the frame and different numbers of dots on each line, line information of frame configuration information of each R, G, and B frame of the still image, The dot information is set to different values and transmitted. Therefore, by using this frame configuration information, it is possible to easily transmit a still image with a certain specific encoding parameter, and then transmit a still image with a different encoding parameter.

Next, a method of increasing the prediction accuracy of the first dot on the first line of an image in a predictive coding method using the coding transmission method of the present invention will be described. In the prediction formula in Figure ₅ , if we consider the case where we predict the first line by setting The closer they get, the worse the prediction accuracy becomes. The same applies to the prediction for the first dot. This prediction error becomes smaller after several lines or dots have passed.
Therefore, in order to improve the prediction accuracy of these first regions, redundant lines and dots having the same value as the first line or first dot are added. That is, although the image data input to the encoding unit 3 is in the format shown in FIG. 2, this is hypothetically considered as the data shown in FIG. 8. In other words, the original information has l〓 line, P〓
It is assumed that the dot information is added before the first line and dot, and its value is the same as that of each first line and first dot. The number of additions may be approximately several times the positions of the reference dots A, B, and x in the prediction formula shown in FIG. 5, and in the case of FIG. 5, it is approximately α=β=3. FIG. 9 shows the structure of frame configuration information and line configuration information in this case. In Figure 9,
The line information is composed of the previous value line length l〓 and the line length l, and the dot information is composed of the previous value dot length P〓 and the dot length P. The encoded information is the number of quantization bits n. The information on the previous value line l〓 and the previous value dot P〓 is added when the control unit 5 transfers the same line and the same dot to the α line and β dot, respectively, when controlling the transfer of data from the memory unit 2 to the encoding unit. This can be achieved with

Encoding still image information from the camera in R, G, and B
When doing this for each component, the transmission efficiency can be increased by changing the number n of quantization bits for each component. When such encoding is performed, control can be performed by defining the number of quantization bits in the encoding information section of the frame and header.

The line count in the line configuration information is used as a count value of the number of lines of encoded data, and is used to separate information for each line and confirm the receiving line number, and to detect data loss due to transmission errors. .

Effects of the Invention According to the encoding transmission method of the present invention, information on the number of lines and dots of the image to be encoded is transmitted as frame configuration information, so that the number of lines and dots of the image can be adjusted according to the type of input image. It is possible to vary the configuration of encoding parameters such as the number of dots and the number of quantization bits. Further, by adding information on the first line of the image and information on the first dot to the information on the original image signal and transmitting the information, it is possible to improve the accuracy of encoding. In addition, the number of quantization bits and even the prediction formula can be changed depending on the type of image signal, making it possible to use a flexible encoding method depending on the image signal, and improving the overall transmission efficiency. You can measure your improvement.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a transmission device embodying a conventional image information encoding method, Fig. 2 is a block diagram of a screen memory, Fig. 3 is a block diagram of the DPCM encoding circuit in Fig. 1, and Fig. 4 is a block diagram of the same DPCM decoding circuit, Fig. 5 is an explanatory diagram of an example of the prediction formula, and Fig. 6
The figure is a block diagram of image encoding in a conventional embodiment.
8 is a configuration diagram of a transmission code sequence in an embodiment of the present invention, FIG. 8 is a configuration diagram of encoded image data, and FIG. 9 is a configuration diagram of frame configuration information and line configuration information in FIG. 7.

Claims (1)

[Claims] 1. In a method of encoding an image signal in units of frames, adding a frame header pattern, and transmitting encoded information, a code sequence to be transmitted is divided into frame configuration information, line configuration information, and code. The frame configuration information includes a frame identification representing the frame type, line information representing line information composing the frame, dot information representing information on the dots composing the line, and representing the type and parameters of the encoding method. 1. An image encoding and transmitting method comprising encoded information, the line configuration information comprising a line identification code and a line count indicating a count value of the number of lines. 2. As an image signal, the image signal consisting of R, G, and B components is predictively encoded, and the number n of quantization bits, which is a parameter of the predictive encoding, is set to the R,
2. The image encoding and transmitting method according to claim 1, wherein the number of quantization bits n is set in the encoding information section of the frame structure information section by changing each of the G and B components. 3 Targeting an image signal consisting of l lines and P dots as an input signal, add the first l line and the first P dot of each line as transmission encoded data to the original image signal, and convert these values into It consists of encoded data of the first line and first dot of the original input image signal, and the line information of the frame configuration information,
2. The image encoding and transmitting method according to claim 1, wherein the values of previous value line length l and previous value bit length P are set in the dot information section, respectively.