JP2800270B2 - Image communication device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image communication apparatus for transmitting and receiving image data using a communication system of a charge system in which a charge increases stepwise with respect to communication time, and more particularly to a facsimile or stationary The present invention relates to an image communication device that performs communication by compressing an image signal via a communication line such as an image communication device.

2. Description of the Related Art Conventionally, when transmitting a large amount of data such as an image, the amount of transmitted data has been reduced by performing high-efficiency encoding of an image signal or reducing the resolution of an image in order to effectively use a line. Was. In a conventional image communication apparatus, for example, a facsimile apparatus, when a transmission mode (eg, standard mode: 3.85 lines / mm, fine mode: 7.7 lines / mm) is set, the data amount is determined by an image to be transmitted. In the facsimile image, in the fine mode, since the pixel is composed of 8 × 7.7 dots per 1 mm square, the total number of pixels of the JIS A4 document is about 4M dots. Therefore, the basic information amount of an A4 facsimile image is about 0.5 Mbytes. When this is coded by the Modified Read (MR) method, which is a G3 facsimile coding method, it is about 1/10
Compressed. Also, since the amount of information currently transmitted on the telephone line is 9600 bits per second, it takes only about 40 seconds in the fine mode to transmit one page of an A4-size facsimile image using the telephone line. Also, if you send in the standard mode of 3.85 lines / mm, you can send in about 20 seconds. Further, when this is transmitted using a G4 facsimile using a 64 kbps digital line, if it is coded by an MMR (Modified MR) method, which is a G4 facsimile coding method, it is about 1/15 to
Since it is compressed to 1/20, it can be transmitted in about 3 to 4 seconds.

Problems to be Solved by the Invention On the other hand, the setting of the call charge in the circuit switching of the telephone line or the ISDN line increases stepwise after a certain period of time irrespective of the contents of the call and the amount of information, When transmission can be performed at such a high speed, it is not uncommon for the transmission to be completed with a lot of time before the fee increases, depending on the number of sheets to be transmitted and the amount of information on the paper surface.

However, in a conventional facsimile machine or the like, this extra time during which transmission can be performed at the same fee has not been effectively used.

Means for Solving the Problems The present invention provides a communication fee system memory prepared for each line distance / communication time / weekday daytime / nighttime / holiday / midnight, an encoding unit for performing encoding based on encoding parameters, The object is achieved by providing a total data amount of the coded data and a control unit for controlling a coding parameter with reference to the communication fee system memory.

According to the present invention, after performing encoding based on encoding parameters specified in advance, the present invention calculates the time required for communication from the total amount of encoded data, Based on the time and the communication partner, the longest communication time that can be communicated at the same charge as that required from the contents of the communication fee system memory based on the time and the communication partner is obtained, the encoding parameter is controlled according to the value, and the encoding result is obtained. By determining the encoding parameters so that the total data amount becomes the closest without exceeding the data amount that can be sent within the longest communication time, it is possible to transmit a higher quality image at the same fee. .

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of an image communication apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 101 denotes a key input unit for inputting a dial or a transmission mode; 102, an inter-MA distance memory for registering a distance between line distance measuring stations in a unit area (MA: message area); 103 is a communication charge system memory for storing the relationship between communication areas, communication time, and charges for each day / night / holiday / midnight on weekdays,
104 is a central control unit for controlling the entire apparatus, 105 is an image input unit for digitizing and inputting image signals, 106 is a selector for selecting an input signal, and 107 is a pixel density for reducing the amount of information of an encoding target image. A converter 108, an encoder for reducing the number of transmission codes, 109, a memory for temporarily storing encoded data, 110, a communication for executing a communication procedure between the exchange and the partner terminal and transmitting the data. A control unit 111 is a line interface unit that performs electrical signal control of the line, 112 is a decoding unit that creates an original signal from encoded data, and 113 is a clock unit that manages the day of the week and the current time.

The operation of the above configuration will be described below.

In the case of transmitting an image, the key input unit 101 notifies the central control unit 104 via the line 120 of these information when the other party's dial information, transmission mode, and transmission start instruction are input.
The central control unit 104 issues a transmission request via the line 131 to the communication control unit 110 to set up a communication path with a transmission partner. The communication control unit 110 sets up a communication path by exchanging communication procedures with the exchange and the partner terminal via the lines 138 and 139, the line interface unit 111 and the subscriber lines 140 and 141. When the communication path is set, the communication control unit 11
At 0, the connection completion is notified to the central control unit 104 via the line 132.

The central control unit 104 instructs the image input unit 105 to start inputting via the line 125 prior to a transmission request to the communication control unit 110. The encoding is performed a plurality of times to adjust the code amount, and the first input is instructed to the selector 106 via the line 126 so as to be the input image signal. In the first encoding, encoding parameters are set so as to obtain the best image quality, and the encoding is notified to the encoding unit 108 via the line 128. This is because if the input image signal is stored in the memory as it is, the memory capacity becomes enormous, so that the data is encoded and the amount of data is passed through. This is for use in inputting the next encoding. The image input unit 105 inputs the image, digitizes the image, and transmits the digitized image to the selector 106 via the line 133. The selector 106 selects the image signal via the line 133 based on the control signal 126 and
Send to 4. The image density conversion unit 107 is composed of a shift register or a line memory for several lines,
Writing and reading are performed based on the control signal from 7. In the first encoding, the image signal is read out to the line 135 without thinning out pixels or lines. The encoding unit 108 performs encoding based on the control signal received via the line 128. FIG. 2 shows the configuration of the encoding unit in the case of the image communication apparatus for the other gradation image in the first embodiment.

Here, the encoding section 108 will be described in more detail with reference to FIG. 201 is an encoding control unit that controls the operation of the entire encoding unit, 202 is a subtractor, 203 is a quantizer, 204
Is a variable length encoder, 205 is a predictor, and 206 is an adder.
The coding control unit 201 selects quantization and a prediction function based on the coding control parameters received via the line 128, and the quantization unit 203, the prediction unit 205 and the variable length coding via the lines 212 and 213, respectively. Notify section 204. On the other hand, the subtractor 202
The difference between the above image signal and the predicted signal on line 216 is sent to line 214. The quantization unit 203 quantizes this difference signal by the quantizer 203 selected earlier, and outputs it to the line 215 as a prediction error signal. Further, the prediction signal on the line 216 and the prediction error signal on the line 215 are added by the adder 206 and output to the reproduction signal 217 as a reproduction signal. The prediction unit 205 predicts the value of the next image signal based on the reproduced signal and the selected prediction function, and outputs the predicted value to the line 216 as a prediction signal. The prediction error signal obtained in this way is subjected to variable-length coding by the variable-length coding unit 204, and the coding control information obtained via the lines 212 and 213 is also coded and transmitted to the line 136. At the same time, the encoding control unit 201 is notified of the code length of the transmitted code via the line 211. The coding control unit 201 calculates the total code length based on this, and sends the result to the line 129. In the case of an image communication device that targets a binary image like a facsimile, the MH
(Modified Huffmann) or MR, M
Coding using a method such as MR is used.

 Here, returning to FIG. 1, the description will be continued.

The memory 109 temporarily stores the encoded data from the encoding unit 108 based on the write control signal from the central control unit 104. When the encoding of the image to be transmitted is completed, the central control unit 104
Receives the total number of codes from encoder 108 via line 129,
An expected communication time is calculated from this and a preset line speed. Also, the current time and date are read out from the timing section 113 via lines 146 and 147, and the daytime / nighttime / holiday /
It determines whether it is midnight, and based on the address of its own device and the address (dial) of the communication partner device, the MA distance memory 102
The communication distance is read via lines 121 and 122 from. Further, based on the unit fee and unit communication time table for each communication distance prepared for daytime / nighttime / holiday / midnight on weekdays written in the communication fee system memory 103 via the lines 123 and 124, the date and time, the communication distance The unit communication time and the unit charge are read out, and the charge for the estimated communication time is calculated. If this fee is the minimum fee, the obtained encoded data is used for transmission, a transmission request is issued to the communication control unit 110 via the line 131, and a notification of connection completion is transmitted from the communication control unit 110 via the line 132. , And sends a read control signal to the memory 109 via the line 130 to transfer the encoded data in the memory to the line 13.
Transfer to the communication control unit 110 via 7. The communication control unit 110 transmits data on a communication path set via the lines 138 and 139, the line interface unit 111, and the subscriber lines 140 and 141.

If the charge for the expected communication time is not the lowest charge, the encoding is subsequently performed based on the transmission mode input from the key input unit 101. Therefore, the central control unit 104
Instructs the decoding unit 112 to start decoding via the line 143. In addition, the transmission mode instructed by the selector 106 to select a reproduced image signal via 126, and the key input to the pixel density conversion unit 107 and the encoding unit 108 via lines 127 and 128, respectively. Is transmitted according to the control parameter. The decoding unit 108 sends a read control signal to the memory 109.
144, and sequentially outputs the encoded data from the memory 109,
The readout image signal is read out to a line 145, and after decoding, the reproduced image signal is output to 142. The selector 106 selects a playback signal in the future,
The data is sent to the pixel density conversion unit 107 via a line 127. In the pixel density conversion unit 107, the image signal is thinned out for pixels and lines, and is read out to a line 135. The encoding unit 108 performs encoding based on the control signal received via the line 128. memory
At 109, the encoded data from the encoding unit 108 is temporarily stored based on the write control signal from the central control unit 104.

Here, at the same time as the first encoding, the key input unit 10
The expected communication time for the transmission mode specified in 1 is calculated, the unit communication time and the unit charge for the date and time, the communication distance, and the maximum communication time for the same charge as the communication charge for the expected communication time are obtained.

If the expected communication time in the encoding mode that initially obtains the highest image quality does not exceed the maximum time, data encoded in the encoding mode that provides the highest image quality is used for transmission.
If the maximum time has been exceeded, the difference between the maximum time at which communication can be performed at the same charge and the expected communication time when encoding in the key-input transmission mode is determined. If this difference is smaller than a preset threshold value, the encoded data obtained when encoding in the key-input transmission mode is used for transmission.

If the difference from the maximum communication time for the same fee is larger than the threshold, the encoding parameter is changed and encoding is performed again. For this reason, the central control unit 104 instructs the decoding unit 112 via a line 143 to start decoding. Selector 1
06 is instructed to select a reproduced image signal via a line 126, and the pixel density conversion unit 107 and the encoding unit 108 are transmitted from the key-input transmission mode via lines 127 and 128, respectively. Also transmits control parameters set to improve image quality. The decoding unit 108 outputs a read control signal 144 to the memory 109, sequentially reads out the data encoded in the encoding mode having the highest image quality from the memory onto the line 145, decodes the decoded image signal on the line 142, Output to The selector 106 again selects a reproduction signal and sends it to the pixel density conversion unit 107 via 134. In the pixel density conversion unit 107, the image signal is thinned out for pixels and lines, and is read out to a line 135. The encoding unit 108 performs encoding based on the control signal received via the line 128. The memory 109 temporarily stores the encoded data from the encoding unit 108 based on the write control signal from the central control unit 104.

The central control unit 104 calculates the expected communication time in the same manner as in the first encoding, and if the expected communication time does not exceed the maximum time, the last encoded data is used for transmission.
If the maximum time has been exceeded, encoded data obtained by encoding in the key-input transmission mode is used for transmission.

The coded data obtained in this way is transmitted to the partner device in the same procedure as described above, and when transmission of all coded data is completed, the communication control unit 110 establishes a communication path according to the procedure. Disconnect, release and notify central controller 104 via line 132.

What has been described above will be described with reference to FIG. 3 showing the relationship between the communication time and the communication fee. As shown in FIG. 3, the present invention takes, for example, 60 seconds when transmitting in the standard mode, and 120 seconds when transmitting in the higher quality fine mode.
When there is an image that takes 240 seconds to transmit in the super fine mode of the highest image quality, even if the standard mode is selected as the transmission mode, it is possible to transmit in the higher quality fine mode at the same charge.

Effect of the Invention As described above, the present invention provides the same communication fee by switching the encoding parameter in accordance with the fee system when using a communication size having a fixed fee system for the communication time. This makes it possible to transmit a higher-quality image, and the effect is great.

[Brief description of the drawings]

FIG. 1 is a block diagram of an image communication apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram of an encoding section which is a main part of the image communication apparatus, and FIG. 3 is a conceptual graph illustrating the concept of the present invention. 101: Key input unit, 102: MA distance memory, 103:
Communication charge system memory, 104 central control unit, 105 image input unit, 106 selector, 107 pixel density conversion unit, 10
8 ... encoding unit, 109 ... memory, 110 ... communication control unit, 1
11 ... line interface unit, 112 ... decoding unit.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04N 1/32-1/36 H04N 1/41-1/44

Claims (2)

(57) [Claims] 1. A distance memory for checking a line distance from a self address and a partner address, and a communication time section in which a charge or a charge is constant based on charge parameters such as a line distance, a communication time, and a discount time period of a night holiday. A communication charge system memory to be referred to calculate, an encoding unit that encodes image data based on the encoding parameter, and a control unit that controls the encoding parameter, wherein the control unit is set in advance to a value. Estimating the communication time from the data amount and the line speed at that time when the input image signal is encoded based on the encoding parameter, referring to the charge system memory from the estimated communication time and other charge parameters. The maximum amount of data that can be transmitted at a specific fee is determined, and the encoding parameters are set so that the total amount of data resulting from encoding is the closest without exceeding this maximum amount of data. Change the image communication apparatus which performs coding by applying feedback to the encoding unit. 2. The image communication apparatus according to claim 1, wherein lossless transform coding is used for coding, and a pixel density conversion rate is used as a coding parameter.