JPS60100875A - Transmitter of still picture - Google Patents

Abstract

PURPOSE:To eliminate buffer memory and to shorten time transmitting data by decoding a variable length DPCM code together with data transmission. CONSTITUTION:A video signal from a camera is stored in a picture memroy 2 through an A/D convertor 1. A controller 10 activates a transmitting circuit 9 and a variable length DPCM encoding circuit 3 at the same time. Due to the activation an address control 5 outputs a scanning address to the memory 2, and supplies contents of the memory 2 to an encoder 4. An output of the encoder 4 is sent to the transmitting circuit 9 through a variable length/fixed length conversion circuit 6. On the other hand, when a final decision circuit 11 detects the final scanning of the memory 2, the circuit 11 transmits a transmitting termination signal to the transmitting circuit 9. As a result, a variable length DPCM code is encoded together with data transmission. Thus buffer memory can be eliminated and time for data transmission can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION ■Technical field of the invention The present invention relates to a still image transmitting device, particularly a still image transmitting device using a variable length DPC.
When M-encoded and digitally transmitted, send @? with the data final flag generated from the encoding circuit. The present invention relates to a still image transmitting apparatus that performs variable length DPCM encoding simultaneously with data transmission.

■Prior art and problems FIG. 1 shows an example of a conventional still image transmitting device. In the figure, 1 is an analog/digital converter, 2 is an image memory, 3 is a variable length DPCM encoding circuit, 4 is an encoding section, 5 is an address control section, 6 is a variable length/fixed length conversion circuit, and 1 is a buffer. Memory, 8 is an address counter, 9 is a transmitting circuit,
10 represents a control section.

When the control unit 10 activates the variable length DPCM encoding circuit 3 in order to transmit still image data stored in the nine-image memory 2 via the analog/digital converter l, the address control unit 5 Image data is sequentially read from the image memory 2 at the indicated address, and is variable-length DPCM encoded (differential encoded) by the encoder 4. The encoded data is processed by a variable length/fixed length conversion circuit 6.

For example, it is compiled into fixed length data in units of 8 pits.

The data is stored in the buffer memory 7. The number of fixed length data to be stored is counted by the address counter 8, and the control unit 1o starts the transmitting circuit 9 after DPCM encoding is completed, and also starts the transmitting circuit 9 at the time of starting the address counter 8.
The value of is notified as the transmission data length. The transmission circuit 9 counts each byte of data transmitted, and ends the transmission when the rrt value reaches the above-mentioned transmission data length.
Generally, in digital transmission of still images, etc., there are two types of band compression methods: fixed length DPCM and variable length DPCM. Variable length DPC using the device as shown in Figure 1
The M system has the advantage of short average transmission bit length and high image quality. However, the variable length DPCM method has the disadvantage that the transmission bit length cannot be known in advance when starting up the transmission circuit, since the transmission bit length changes depending on the image quality. That is, unless the DPCM conversion is completed.

I don't know how many bits to send.

Therefore, the conventional method is as shown in FIG. 1, for example.

The converted data is once stored in the buffer memory 7.

Transmission is started after all data for one screen has been converted, but this has disadvantages such as requiring a large amount of buffer memory. There is a problem in that variable length DPCM encoding takes time in addition to transmission time. This is particularly a problem during high-speed transmission, such as at 5KBPS.

(QObject and Structure of the Invention The present invention solves the above problems by performing variable length DPCM encoding in accordance with data transmission, thereby making it possible to eliminate the buffer memory.

It also aims to shorten the time required for data transmission. Therefore, the still image transmitting device of the present invention includes an image memory in which digital image information is stored, and a DP that encodes information read out from the image memory using variable length DPCM encoding.
DP by the CM encoding circuit and the DPCM encoding circuit.
In a still image transmitting device equipped with a transmitting circuit that transmits CM-encoded image information to a communication line, the DPCM
The encoding circuit detects the end of the scan of the image memory and sends a signal indicating the final transmission data to the transmission circuit, and the transmission circuit terminates data transmission by the signal indicating the final transmission data. configured,
It is characterized by parallel processing of variable length DPCM encoding and data transmission. Embodiments will be described below with reference to the drawings.

0 Examples of the invention FIG. 2 shows the configuration of an embodiment of the present invention. In the figure.

Symbols 6, 9, and 10 correspond to FIG.

11 represents a final judgment circuit, and 12 represents a circuit.

A video signal from a camera is converted into a digital signal by an analog/digital converter 1 and stored in an image memory 2 only outside the vertical synchronization interval, for example. variable length DI)
The CM encoding circuit 3 performs high-efficiency compression encoding of the still image data stored in the two-image memory 2. In the case of the present invention, the control unit 10.

When encoding and transmitting still image data, the transmitting circuit 9
and variable length DPCM encoding are simultaneously activated. By this activation, the address control section 5 outputs an address for scanning the 9-image memory 2, and the contents of the image memory 2 at the address position are read.

The data is supplied to the encoding unit 4. The encoding unit 4 encodes the supplied data while referring to the data that has already been read out. As is well known, frequently appearing patterns are given short bit lengths, and rarely appearing patterns are given relatively long bit lengths.

Since encoding is performed, the encoded result has a variable length.

The variable length/fixed length conversion circuit 6 has nine shift registers, for example, and collects the variable length bit data output from the encoder 4 in units of 8 bits.

It is immediately sent to the transmitting circuit 9. That is, variable length DPC
When the M-encoded data has a fixed length of 1 byte, it is sent to the transmitting circuit 9 one by one.

The transmitting circuit 9 transfers the data to a receiving device (not shown) through an audio line.

The final determination circuit 11 refers to the scan address for the image memory 2 generated by the address control unit 5, and
This detects the final data to be converted by the encoding unit 4. When the final data is detected, the final data bit is output. The final data bit passes through the 'r'-to-12 and is converted by the strobe signal of the variable length/fixed length conversion circuit 6.
At the timing when the variable length/fixed length conversion circuit 6 sends out the last fixed length 1-byte data, the transmission circuit 9 is notified as a transmission end signal. In addition, if the last converted data does not fill 1 byte, a dummy code is filled in and
Fixed length of 1 byte. When the transmission circuit 9 receives the transmission end signal, it transmits the data at that time, and then
Finish sending. That is, by sending a signal indicating the final data generated by the variable length DPCM encoding circuit 3 to the transmitting circuit 9, the transmitting circuit 9 can obtain the timing to end the transmission, and transfer the data to the buffer memory. Variable length DPCM encoding can be performed in conjunction with data transmission without storing encoded data.

[F] As described in detail, according to the present invention, since variable length nPCM encoding and data transmission are performed simultaneously, a buffer memory of about 1, 40 bytes, for example, is not required at all. Furthermore, the time required to encode and transmit the original still image data can be significantly reduced.

[Brief explanation of the drawing]

FIG. 1 shows an example of a conventional still image transmitting device, and FIG. 2 shows the configuration of an embodiment of the present invention. In the figure, 2 is an image memory, 3 is a variable length DPCM encoding circuit, 5 is an address control section, 6 is a variable length/fixed length conversion circuit, 9 is a transmission circuit, and 11 is a final determination circuit. Patent applicant Fujitsu Limited

Claims (1)

[Claims] An image memory in which digital image information is stored. Still image transmission comprising: a DPCM encoding circuit for variable length DPCM encoding of information read from the image memory; and a transmission circuit for transmitting the image information DPCM encoded by the DPCM encoding circuit to a communication line. In the device,
The above DPCM encoding circuit is as follows. The transmission circuit is configured to detect the end of the scan of the image memory and send a signal indicating the final transmission data to the transmission circuit, and the transmission circuit is configured to terminate the data transmission by the signal indicating the final transmission data. DPCM
A still image transmitting device characterized by processing encoding and data transmission in parallel.