JPS61245763A - Line-density automatic changeover facsimile equipment - Google Patents

Abstract

PURPOSE:To obtain a reproduced picture plane with proper resolution without intervention of subjective judgment of the operator by deciding the complication of a sent picture plane depending on the number of black runs in one line to be sent and a change quantity from the preceding line and selecting the line density in the scanning direction. CONSTITUTION:A facsimile picture signal is inputted to a line memory section 1 and a black run counter 6. When a 1-line transfer signal C is turned off, the black run counter 6 stores a count N in a register 7, and the count N is compared with the 1st specified value 1 by the 1st comparator 8. When the count N is smaller than the 1st specified value, the main scanning line density information M is brought into logical 1 and outputted to a line memory write control section 2 from the 1st comparator 8. The line memory write control section 2 controls the write on the line memory section 1 in response to the main scanning line-density information M.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a facsimile machine, in particular, a facsimile machine that automatically switches the line density of a transmitted image signal depending on the complexity and precision of the original screen to be transmitted. The present invention relates to a facsimile device with automatic linear density switching.

Summary of the Invention The present invention provides a facsimile device that determines the complexity of an original image signal based on the number of black runs in one line and the amount of change in the number of black runs between lines, and provides an image with a line density that is adapted to the complexity of the original. The signal is encoded and transmitted, and the receiving side decodes and reproduces the original image signal.

The complexity of the document screen can be automatically determined without involving the operator's subjectivity, and the document can be transmitted at an appropriate linear density that is suited to the complexity of the document, reducing image quality deterioration and improving transmission efficiency. It has the effect of being able to

BACKGROUND TECHNOLOGY Currently, facsimile machines in general use quantize image information obtained by scanning an original in the main scanning direction into black and white binary values to produce a facsimile image signal, and encode the facsimile image signal. A configuration is used in which the encoded data is decoded on the receiving side, and the original facsimile image signal is reproduced to restore the original image on the recording paper.

The above encoding method uses 1 International Telegraph Consultative Committee (CCI)
TT) One-dimensional MH (Modified Huffman) encoding method and two-dimensional MR (Modified Huffman) encoding method shown in Recommendation T4
read) encoding methods, etc.

The former is a method in which the facsimile image signal is converted into a variable length code called an MH code according to the run length of black and white pixels generated in the facsimile image signal and then transmitted. The above variable-length code statistically calculates the black and white run lengths that occur in a document, assigns short code bits to run lengths that occur frequently, and assigns long code bits to run lengths that occur less frequently. It is configured by assigning bits.

The latter uses the correlation of image signals in the sub-scanning direction, and the MR
In this method, a facsimile image signal is encoded and transmitted using a code called a mode code indicating the distance between pixel change points between two lines.

Through the various encoding processes described above, the redundancy of the facsimile image signal can be suppressed and the transmission time can be shortened. However, all of these encode the information in the facsimile image signal as is, so if the facsimile image signal is complex, the number of encoded bits will increase, and if the original image is simple, the number of encoded bits will decrease. . Therefore, simple documents can be transmitted in a short time.

Furthermore, in order to improve transmission efficiency, some systems transmit data by switching the density of scanning lines depending on the image information density of the original image. That is, when the original screen is simple, the transmission time is shortened by reducing the scanning line density and transmitting. However, there is a drawback that the scanning line density cannot be reduced when a single transmitted document contains both complex and simple images. This is because if the scanning line density is reduced, image information of the original image will be lost and the image quality of complex screen parts will deteriorate.

On the other hand, facsimile machines with further improved image quality and high-resolution functions are also required and are now commercially available. When a document is transmitted using such a high resolution function, it is possible to obtain a much more precise and better image quality than when transmitting in a conventional fine mode, but the transmission time is increased accordingly. Furthermore, facsimile machines with such high-resolution functions generally have the function of transmitting at a resolution called fine/standard, similar to conventional facsimile machines, in addition to the high-definition resolution function. Whether or not to transmit the manuscript can be selected based on the subjective judgment of one sender. Therefore, if the sender makes a mistake in selection, there is a drawback that the transmission time may take longer than necessary or the image quality may deteriorate. In addition, there is a precise screen part in one manuscript.

When simple screen parts are mixed, it is difficult to judge which resolution is appropriate to use.

Problems to be Solved by the Invention The present invention solves the various drawbacks of the conventional technology described above, and enables the transmission of images in the middle of one document without intervening the subjective judgment of one sender according to the image information density of the transmitted image. This also attempts to improve transmission efficiency while minimizing deterioration in image quality by changing resolution selection.

Means for Solving the Problems The automatic line density switching facsimile apparatus of the present invention includes a line memory section for temporarily storing black and white binary image signals, and a black run section for counting the number of black runs in the main scanning direction in one line. Count-and.

a first comparing the output value of the black run counter with a first specified value;
a second comparator that compares the difference between the output value of the black run counter and the number of black runs one line before with a second specified value; a line memory write control section that controls writing in the line memory section according to an output signal;

an encoding unit that reads image signals line by line from the line memory unit in accordance with the output of the line memory write control unit, performs encoding processing, adds tag bits indicating scanning line density to encoded data, and sends the coded data; , a transmission buffer memory for speed matching inserted between the encoding unit and the line, a reception buffer memory for temporarily storing the encoded data received from the line, and a binary image signal of black and white for the encoded data. and a decoding unit that decodes the original image signal by enlarging the decoded image signal in the main scanning direction according to the tag bit.

and a recording control section that records the reproduced image signal for one life output from the decoding section on the recording paper the number of times indicated by the tag bit.

The complexity of the original image signal is judged by the number of black runs in one line and the amount of change in the number of black runs between lines, and the image signal is encoded and transmitted with a line density that is adapted to the complexity of the original, and the receiving side The original image signal is decoded and reproduced.

Embodiments of the Invention Next, the present invention will be described in detail with reference to the drawings.

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

In other words, black and white 2 that always reads the original with high precision resolution.
A few facsimile image signals are input to the line memory section 1 and the black run counter 6.

The line memory section 1 stores the input facsimile image signal for a plurality of lines in units of 1 line, and the black run counter 6 counts the number of black runs in the facsimile image signal for 1 line, When signal C turns off, black run counter 6
The count value of is written to register 7.

When writing is possible in the line memory section 1, the line memory write control section 2 turns on the l-line transfer request signal B and requests the image signal reading section (not shown) to transfer one line of facsimile image signals. . As a result, an image signal A, a transfer lock D, and a one line transfer in progress signal C are sent from the image signal reading section. When the 1-line transfer raw signal C is input, the 1-line transfer request signal B is turned off. When one line of image signals has been transferred, the one line transfer in progress signal C is turned off, and the line memory write control section 2 turns on the one line transfer request signal B to request transfer of the next one line.

By repeating such operations, image signals are received from the image signal reading section and stored in the line memory section 1.

On the other hand, when the l-line transfer raw signal C is turned off, the count value N of the black run counter 6 is stored in the register 7, and the count value N
is compared with the first specified value 1 by the first comparator 8. If the count value N is smaller than the first specified value, the first comparator 8 outputs the main scanning line density information M as "1" to the line memory write control unit 2. “0” in the main scanning line density information M indicates the main scanning line density in high definition (16 dots/lIm)
'1' means fineness (8 dots/+1
1) Indicates that the sub-scanning line density should be fine (
7,7 lines/layer m) to standard (3,85 lines/ff
Switching to (i) is performed only when the main scanning line density becomes fine. In addition, the sub-scanning line density in the case of high definition is 1
5.4 lines/layer m.

Line memory write control section 2 controls writing to line memory section 1 according to main scanning line density information M. That is, when the main scanning line density information M is "0", the writing line memory of the line memory section 1 is switched by the memory switching signal H to start writing the image signal of the next line, and the main scanning line density information M is "1". ”, writing of the next line is prohibited by the write inhibit signal U', and only the image signal transfer control is performed between the image signal reading unit and the image signal reading unit. Although the signal is input, it is not written to the line memory section l. Then, at the third line, the line memory of the line memory section 1 is switched and writing of the image signal is started. In addition, while the second line is being discarded,
A state holding signal U is supplied to the linear density determining circuit 5 to maintain the state of the linear density determining circuit 5 as it is.

The linear density determining circuit 5 includes a black run counter 6. Register 7.9
．． First comparator8. It incorporates a subtracter lO1, a second comparator 11, etc., and maintains these current conditions as long as the status holding signal U is on. If the state holding signal U is off, the contents of the register 7 are latched into the register 9 at the same time as the l-line transfer raw signal C is turned on, and the black run counter 6 starts counting the number of black runs. Then, by turning off the 1-line transfer signal C, the count value of the black run counter 6 is latched in the register 7, and the output value 0 of the register 7 is compared with the first specified value by the first comparator 8, When it is smaller than the first specified value, main scanning line density information M is turned on. On the other hand, the subtracter 10 calculates the difference between the output of the register 7 and the output value P of the register 9, and the second comparator 11 performs sub-scanning when the output value of the subtracter 1O is smaller than the second specified value 2. The fact that the main scanning line density information M and the sub-scanning line density information -L are both "1", where the line density information -L is "1", means that the resolution is switched from precision to standard. but,
If the main scanning line density information M is "0", it means that the image is high definition even if the sub scanning line density information M is "1".

Therefore, if the main scanning line density information M is "0", the line memory write control section 2 switches the line memory of the line memory section l as described above (regardless of the sub-scanning line density information). At the same time as writing of the next line of signals is started, the one line read enable signal H to the encoder 3 is set to "L".

Main scanning line density information M is “1” and sub-scanning line density information is “1”.
0'', the write line is switched to the line memory unit 1 by the memory switching signal R, and at the same time the write line is switched to the line memory unit 1 by the memory switching signal
Set the 1 line read enable signal H to “1” for
For the linear density determination circuit 5, the state holding signal U is set to "1" to hold the state. In this case, write inhibit signal U
Accordingly, the image signal for the next line is discarded and the image signal for the next line is written on the write line, that is, the sub-scanning line density is thinned out to 1/2.

Main scanning line density information M and sub-scanning line density information are both "1"
When this is the case, without switching the write line of the line memory section 1, the state holding signal U is set to "I11" for the line density determination circuit 5, and the next one is set by the write inhibit signal U.
The line image signal is discarded. Then, the next line of image signals is written to the previous writing line (the first written image signal disappears), and the state holding signal U is turned off to count the number of black runs. Then, at the same time as writing is completed, the write line of the line memory section l is switched, and at the same time, the line read enable signal H to the encoding section 3 is set to "1", and the next line is discarded by the write inhibit signal U'. do. That is, in this case, the sub-scanning lines are thinned out to 1/4.

By repeating the above operations, the scanning line density is automatically determined. Then, in order to notify the receiver side of the main scanning line density information M and the sub scanning line density information, the line memory write control unit 2 temporarily stores the main scanning line density information M and the sub scanning line density information. , when the encoding unit 3 reads one line worth of signals from the line memory unit 1, it is notified to the encoding unit 3 as main scanning line density information S and sub-scanning line density information T.

When encoding one line of signals output from the line memory section l, the encoding section 3 turns on the line encoding request G to the line memory write control section 2, and turns on the line read enable signal H. When the 1-line read enable signal H is turned on, it outputs an EOL code indicating the beginning of 1 line, and then outputs tag bits according to the main scanning line density information S and the sub-scanning line density information T, Thereafter, the image signal E is read from the line memory unit 1 using the encoding clock F and encoded, and the encoded data J is sent to the transmission buffer memory 4 in synchronization with the transfer lock I. Then, when the 1-line read enable signal H is turned off, the 1-line encoding request G is turned off to complete the encoding process for one line, and the above-described operation is repeated to sequentially encode and transmit each line.

Note that the encoding unit 3 also performs thinning processing of image signals in the main scanning direction during the above-mentioned encoding processing.

That is, when the main scanning line density information S indicates high definition, all the image signals read from the line memory section 1 are encoded, but when the main scanning line density information S indicates fine, the image signals are encoded. Encoding processing is performed by discarding E every other pixel and equivalently reducing the main scanning line density to 1/2.

An example of the structure of encoded data is shown in FIG. In other words, the EOL code (00000000000
After 1), a tag bit indicating whether it is an MH encoded line or an MR encoded line is sent out, and the first step is the density in the main scanning direction (8 dots/Ill+ or 16 dots/m11) and the sub-scanning line density (3 , 85 lines/layer height, 7.7 lines/mm,
After transmitting 2 tag bits to indicate 15.4 lines/all), Ml code or MR encoded data (for one line) is transmitted.

The transmission buffer memory 4 is used to match the speed of the line with the encoding unit 3, and performs a transmission operation by outputting encoded data J in accordance with a read clock from the line.

Note that the above-mentioned first and second specified values are, for example, appropriate values determined experimentally.

FIG. 3 is a block diagram showing an example of the configuration of the receiving section of this embodiment. In other words, encoded data a received from one line
is received buffer memory 1 in synchronization with code transfer lock b.
00, is temporarily stored here, and is sent to the decoding unit 101.
Speed matching is performed between the Then, the decoding unit 10
The encoded data C read out from the reception buffer memory 100 by the read clock d from 1 is sent to the decoding unit 101.
decrypted by When the image signal transfer request e from the recording control unit 102 is turned on, the decoding unit 101 starts decoding processing for one line, first detects the EOL code, analyzes the tag bit, and extracts the tag bit indicating the scanning line density. If the first bit of is “1”, the decoded image signal bit number is transferred as it is as the reproduced image signal f, and the recording control unit 10 along with the lock g
Transfer to 2. Further, a recording count instruction signal informs that this reproduced image signal is written once. If the first bit of the tag bit indicating the scanning line density is "O", the number of bits of the decoded reproduced image signal is expanded to twice the number per pixel and transferred to the recording control unit 102.
If the second bit is "OIT", the recording number instruction signal instructs writing twice, and if the second bit is "°1", the recording number instruction signal instructs writing four times.

When the recording control unit 102 receives the reproduced image signal for one line, it turns off the image signal transfer request e and starts the recording operation. At this time, if it is possible to receive the reproduced image signal of the next line,
The image signal transfer request e is then turned on. Then, the reproduced image signal f is recorded on the recording paper 1@, 2 times, or 4 times in accordance with the instruction of the recording number instruction signal. That is,
When a recordable signal j is turned on to a recording section (not shown), an image signal i is outputted at the same time, and when 1947 worth of image signals have been outputted, the recordable signal j is turned off. When 1947 minutes of recording is completed, feed pulse k is output to feed the recording paper by a predetermined line interval (1/15.4 m), and the above operation is repeated the number of times instructed by the recording number instruction signal. After recording the same line signal for the designated number of times, the image signal transfer request e is turned on again to request transfer of the image signal for one primary line, and the same operation as described above is repeated.

In this embodiment, two types of line densities in the main scanning direction and three types in the sub-scanning direction are automatically selected according to the complexity of the transmission screen, and reproduction is performed at an appropriate resolution without intervening the sender's subjective judgment. This has the effect that the image quality can be obtained with less deterioration of the image quality and the transmission efficiency can be improved.

Effects of the Invention As described above, in the present invention, the complexity of the transmission screen is determined based on the number of black runs in the l line to be transmitted and the amount of change from the previous line, and the system is adapted to the complexity of the transmission screen. Since the linear densities in the main scanning direction and the sub-scanning direction are automatically selected in this manner, a reproduced screen with an appropriate resolution can be obtained without intervening subjective judgment by the operator.

Therefore, there is an effect that image quality is less degraded and transmission efficiency can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is a diagram showing an example of the structure of encoded data used in the above embodiment, and FIG. 3 is a block diagram showing an example of the structure of the receiving section of the above embodiment. In the figure, 1: 2-line memory section, 2: 2-line memory write control section, 3: encoding section, 4: transmission buffer memory,
5: Linear density determination circuit, 6: Black run counter, 7: Register, 8: First comparator, 9: Register, 10: Subtractor, 1
1: second comparator, 100: reception buffer memory, 1
01: Decoding section, 102: Recording control section, A: Image signal, B
: 1-line transfer request signal, C: 19-in transfer signal, D
: Image signal transfer lock, E: Image signal, F: Encoding clock, G: 1 line encoding request, H: 1 line read enable signal, I: Transfer lock, J: Encoding data, K: Reading clock , L: Sub-scanning line density information, M: Main-scanning line density information, N: Black run count value, O, P: Register output value, Q: Black run number change amount, R: Memory switching signal, S: Main scanning Line density information, T: Sub-scanning line density information, U: State holding signal u/
': write inhibit signal, a: encoded data, b: code transfer lock, C: encoded data, d: read clock,
e: Image signal transfer request, f: Playback image signal 1g: Transfer lock, h: Recording number instruction signal, l: Image signal, j: Recordable signal, ni: Feed pulse.

Claims (1)

[Scope of Claims] A line memory unit that temporarily stores black and white binary image signals, a black run counter that counts the number of black runs in the main scanning direction in one line, and an output value of the black run counter. The first value to be compared with the first specified value.
a second comparator that compares the difference between the output value of the black run counter and the number of black runs one line before with a second specified value; a line memory write control section that controls writing in the line memory section according to an output signal; and a line memory write control section that reads image signals line by line from the line memory section and performs encoding processing according to the output of the line memory write control section. , an encoding unit that adds tag bits indicating scanning line density to encoded data and sends it; a transmission buffer memory for rate matching inserted between the encoding unit and the line; and a code received from the line. a reception buffer memory that temporarily stores encoded data; and a reception buffer memory that decodes the encoded data into a black and white binary image signal, and expands the decoded image signal in the main scanning direction according to the tag bit to reproduce the original image signal. A facsimile device with automatic linear density switching, comprising: a decoding section; and a recording control section that records one line of reproduced image signal output from the decoding section on recording paper the number of times indicated by the tag bit. .