JPH0564505B2 - - Google Patents

Description

TECHNICAL FIELD The present invention relates to a facsimile device, and more particularly to a facsimile device having one-dimensional data compression means and two-dimensional data compression means.

Prior Art When performing facsimile communication, test data is generally sent using a high-speed modem prior to sending image information. When a negative response is returned to this test data, the modem rate (transmission speed)
and send the test data again. If negative responses continue, the modem rate is sequentially reduced until a positive response is returned. In this way, transmission of image information is started at the modem rate at which the positive response was received.

On the other hand, there are two types of image information compression methods (encoding methods): a one-dimensional compression method and a two-dimensional compression method. The one-dimensional compression method compresses data based only on information from the currently scanned scan line, and the two-dimensional compression method compresses data by incorporating information from previous scan lines as well. Compared to two-dimensional compression methods, one-dimensional compression methods have disadvantages in that they have lower data compression rates and lower transmission efficiency, but they have the advantage that even when an error occurs on the receiving side, the error spread is small.

There are facsimile apparatuses that coexist with these two types of data compression methods. With this device, when test data is sent at a certain modem rate and a negative response is returned due to a high data transmission error rate on the line, conventionally the data compression method is simply converted to a lower modem rate. has not been converted. In other words, at the time of shipment, the bit switch gives priority to the two-dimensional compression method with better transmission efficiency, and only when there are many errors in the image information, the service person switches to the one-dimensional compression method, which causes less image distortion, and encodes using the one-dimensional compression method. The image information is being sent to the other station. In this way, when a facsimile device that has switched to the one-dimensional compression method transmits to another station, if the data transmission error rate of that line is low, there will be less image distortion, so the transmission efficiency will be higher than the image distortion. It is better to emphasize this and transmit using a two-dimensional compression method. However, in order to transmit using the two-dimensional pressure type method, it is necessary to ask a service person again.

Purpose The purpose of the present invention is to solve the problems of the prior art as described above, and to provide a facsimile device that can automatically select an appropriate data compression method according to the line condition, taking into consideration transmission efficiency and image disturbance. It is about providing.

Configuration The configuration of the present invention will be explained below using one example.

FIG. 1 is a block diagram showing a schematic configuration of a facsimile apparatus according to an embodiment of the present invention.

In FIG. 1, 1 is a control unit that controls protocol establishment, etc., 2 is a data compression unit that has one-dimensional compression means and two-dimensional compression means, 3 is a reading unit that reads image information, and 4 is a plurality of modem rates. 5 is a network control unit (NCU) that controls the communication line network.

Next, the operation of data compression method selection control by the facsimile apparatus shown in FIG. 1 will be explained with reference to the flowchart shown in FIG.

First, the operator calls the other station using a telephone (not shown), confirms that the called station is the desired called station using the CED signal from the called station, and then presses the send button to turn on the device. Switch from the telephone side to the facsimile device side (201, 202). The control unit 1 confirms based on the DI signal from the called station that the called station can also transmit using the two-dimensional compression method (203).

Next, since the line status of the first page is unknown, image quality is more important than transmission efficiency, and the data compression selection signal a sets the mode of the data compression unit 2 to a one-dimensional compression mode with less image distortion. In addition, the transmission speed selection signal b
Set modem 4 to a fast modem rate by
A mode setting command DCS signal is sent to the called station (204).

After that, test data is sent at the set modem rate, and if the data transmission error rate is lower than the specified value and the response signal from the called station is an acknowledgment,
The image information from the reading unit 3 is encoded by the one-dimensional compression means, and the encoded image information is sent out via the network control device 5 by the modem relay (205, 206,
207, 209). If the data transmission error rate is higher than the specified value and the response signal from the called station is a negative response,
The mode of the data compression unit 2 remains the one-dimensional compression mode, and the modem rate of the modem 4 is set to a lower modem rate than the previous modem rate, and this is communicated by the DCS signal (207, 208), and the test data is sent again (205). .

When the control unit 1 finishes sending out one page of image information,
It is determined whether or not there are multiple pages of image information to be transmitted, and if there are multiple pages, this is indicated and an MPS signal is transmitted (210, 215). If there are not multiple pages, send an EOP signal indicating the end of communication, and after receiving the response,
A DCN signal indicating call release is sent and the line is disconnected (211, 212, 213, 214).

If the data transmission error rate is high and the response signal to the MPS signal is a negative response, the process returns to step 204 (215 , 216, 217, 204). If the data transmission error rate is low and the response signal to the MPS signal is a positive response, transmission efficiency is more important than image quality for the next page, and the next page is transmitted using two-dimensional compression means with high transmission efficiency.
Therefore, the control unit 1 receives the data compression means selection signal a.
changes the mode of the data compression unit 2 to the two-dimensional compression mode, and further sets the modem 4 to a high modem rate using the transmission rate selection signal b, and sends a mode setting command DCS signal to the called station (217,
218). The subsequent operation returns to step 205 (218, 205).

In other words, from page 2 onwards, when the data transmission error rate of the line is good and there are few image disturbances, a two-dimensional compression method with good transmission efficiency is selected, and when the data transmission error rate of the line is poor and there are many image disturbances, the error spread is selected. Select a one-dimensional compression means with less.

FIG. 3 is a transmission control signal time chart when a negative response is received after sending the test data when transmitting two pages of image information.

First, the operator calls the other party's station by telephone. The receiving side R that receives the call sends a 2100Hz called station identification signal (CED signal) indicating that the called station (receiving side R) is a non-voice terminal, and also indicates its own functions.
Returns the DIS signal. The control unit 1 of the sending side S,
After confirming the DIS signal, the first page is transmitted using the one-dimensional compression means, so the mode is set to one-dimensional compression means mode.
A modem rate of 9600bps is set, and the receiving side R is commanded to set the transmission mode using the DCS signal. Then, the test data is transmitted through the 9600bps modem rate.
Send TRD. CFR indicating affirmation for it
When the signal is returned, the image information VD1 encoded by the one-dimensional compression means is transmitted.

When the message transmission for the first page is completed, the sending side S sends an MPS signal indicating that the next page is available. On the other hand, upon receiving an RTP signal indicating an acknowledgment,
It is checked whether the image information of the second page can be transmitted by the two-dimensional compression means. In other words, the data compression mode is set to two-dimensional compression mode, and the modem rate is set to
9600bps, and the receiving side R sends a DCS signal to that effect.
After informing the user, the test data TRD is transmitted at a modem rate of 9600bps. When a CFR signal indicating an affirmative response to the test data TRD is received, the image information VD2 encoded by the two-dimensional compression means is encoded at 9600bps.
Transmit at a transmission rate of When the transmission of the image information for the second page is completed, the sending side S sends an EOP indicating the end of communication.
Send a signal. In contrast, if an RTP signal indicating affirmation is returned after the message, it indicates that the call has been canceled.
Sends a DCN signal and a DISC signal indicating line disconnection.

FIG. 4 is a transmission control signal time chart when the response after the message is a negative response when transmitting two pages of image information.

If the response to the MPS signal after the message on the first page is a negative RTN signal, the data transmission error rate of the line is high and high image quality cannot be obtained. Therefore, the one-dimensional compression method with a small error spread is used for the second page as well. Send in the same mode. The modem rate is the same as for the first page, but if you expect higher image quality, you may lower the modem rate.

Effects As explained above, according to the facsimile apparatus of the present invention, it is possible to automatically select an appropriate data compression method according to the line condition, taking into consideration transmission efficiency and image disturbance.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram showing a facsimile apparatus according to an embodiment of the present invention, FIG. 2 is an operation flowchart of FIG. 1, and FIG. 3 is a transmission control signal time chart when the response after a message is an affirmative response.
FIG. 4 is a transmission control signal time chart when the post-message response is a negative response. 1: Control unit, 2: Data compression unit, 3: Reading unit,
4: Modem, 5: Network control device.

Claims (1)

[Claims] 1. In a facsimile device having one-dimensional data compression means and two-dimensional data compression means, 1
For the second page, the one-dimensional data compression means is selected, and from the second page onwards, if the response to the multi-page signal is a positive response, the two-dimensional data compression means is selected, and if the response is negative, the one-dimensional data compression method is selected. A facsimile device characterized in that it is provided with a means for selecting a means.