JPS5851667A - Automatic line density switching system for facsmile device - Google Patents

Abstract

PURPOSE:To determine a suitable scanning line density per scanning line with a simple circuit constitution, by forecasting amount of information of the next line according to the amount of coding information of one line, and controlling the system so as to switch the scanning line density. CONSTITUTION:An encoder 1 performs a coding processing for a facsimile picture signal 12 and transmits a coding data 14 with a coding sampling pulse 15. An information amount discriminating circuit 2 counts a pulse 15, and when the count value, i.e., the number of pre-scanning line coding bit is a prescribed value or over, the generation of codes is instructed to a special code generating circuit 7, which receives the output 51 of the circuit 2 and applies a special code to the encoder 1. The encoder 1 outputs the special code to a data 14. Further, a decoder receives a coding data and a coding sampling pulse from a line section, decodes the data and outputs a picture signal to the picture output together with a line synchronizing code. When a special code detection circuit detects the special code, the detection circuit outputs the instruction of one line skip to a recording section, to switch line density.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises 7 actors 113 devices O automatic linear density switching system;
A facsimile machine that scans a tKJI image horizontally along a scanning line, encodes and transmits the resulting image signal, and predicts the amount of information in the next line according to the amount of encoded information in one line, and then prints it out. *1 This is related to the automatic second grade changeover method.

In general, in a 7-digit printing device, an original image is scanned horizontally along IsK, and the resulting signal is binarized, sampled into extra-layer pixels, and used as a facsimile image signal.

In the facsimile image signal obtained in the ζO manner, there is a strong correlation between pixels in the horizontal scanning line direction, and at the same time, there is also a strong correlation between pixels on adjacent scanning lines.

This kind of correlation between pixels is called the redundancy of a factor-only signal, and it is known that this redundancy ft can be suppressed and efficiently transmitted by encoding the image signal.

In such encoding, a method is usually used in which the amount of information contained in one facsimile image signal is left as is so that the original facsimile image signal is reproduced when it is decoded. Therefore, if the facsimile image signal is simple, the number of encoded bits will decrease, just as the number of encoded bits will increase if the image code becomes complex. ) There is a strong correlation between the number of encoded bits and the amount of information in the 7-axis binary image signal.

In addition, as a means for improving transmission efficiency, there is a method of transmitting images by appropriately switching the Ill1 density of scan a (depending on the level of image information density of the original image) like the original image.

In this method, when the original image is a single image, the image information can be transmitted by reducing the scanning line density, so that the image information transmission time can be shortened.

However, this method has the disadvantage that it is not possible to reduce the linear density when a single original image contains both complex and simple images.

In order to improve this drawback, the amount of image information is determined for each scanning line, and in one OJK image, more scanning lines are used for complex image parts, and rough scanning is used for simple image OS parts. A method has been proposed.

This method has the advantage that when transmitting one original image, the scanning line density can be changed as appropriate depending on the image.

Conventionally, the method of determining the switching of the scanning line density was to monitor the changing state of the facsimile image signal and determine the amount of information. However, it has the disadvantage that it requires a lot of dedicated hardware to judge.

SUMMARY OF THE INVENTION An object of the present invention is to overcome these drawbacks and to provide a facsimile machine which can determine an appropriate scan for each scanning line with a simple circuit configuration.

According to the book *lj1, there is a means for encoding an image signal obtained by scanning an original image in the horizontal direction, a counting circuit for counting the amount of encoded information of one line, and a means for encoding an image signal obtained by scanning an original image in the horizontal direction, and a counting circuit for counting the amount of encoded information for one line. There is also an information amount determination circuit for determining the amount of information that is present in the code form when encoding an image signal, and a specified number of bits for determining the amount of encoded information for one line. The circuit includes a circuit that generates a constructed special code according to the judgment value, and a circuit that detects the special code, predicts the amount of information of the next line according to the amount of encoded information of one line, and switches the scanning SSt variation. An automatic line density switching method for a factor 2 device is obtained, which is characterized by such control.

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

tJIt1 and FIG. 3 are block diagrams showing an embodiment of the present invention. FIG. 1 is a block diagram of the configuration of the transmitting side of the factor 2 device, and FIG. 3 is a block diagram of the configuration of the receiving side. First, in FIG. 111 on the transmitting side, 1 is an encoder, 2 is an information amount judgment circuit, and 3 in the information amount judgment circuit 2 is a counter;
4 is a register, 5 is a comparator, and 6 is a register for storing the comparison specified value bit number.

Further, 7 is a special code generating circuit, 8 in the special code generating circuit 7 is a register storing a special code, 9 is a data selector, and 1G is a register.

Using the time chart in Figure 2, the operation K''
To simplify the explanation, we will assume that the specified number of bits is 5 bits and the number of special code bits is 3 bits. Now that the encoder 1 is ready for operation, Image signal transfer request signal 11 (Fig. 2a) I to the image signal section
ON (level jo) c, the image signal section sends out the encoder IK facsimile image signal 12 and the synchronization signal 13 (FIG. 2b) indicating the separation of the scanning lines of the 1 line. At this time, the encoder 1 encodes the interval facsimile image signal 12 with the synchronization signal 13 at level %lI, and generates the code data $14 together with the code sampling pulse 1s (IIE!I!!1e).
Send 1. The information amount determination circuit 20 counter 3 is reset when the synchronization signal 13 changes from level 0 to level l, counts the number of sampling pulses 15 that are manually applied when the synchronization signal 13 reaches level l', and calculates the counting result. It is output as a counter output 31 (Fig. 112d).

Register 4 shows that synchronization signal 13 changes from level l to level OK'
& Wait, the counter output 311 is stored and its contents are held until the next synchronization signal 13 changes from level 1 to level OK or the image signal transfer request 11 turns OFF (level 1). Further, the contents stored in the register 4 are output as a register value 41 (Fig. t2 e), which indicates the number of code bits of the previous scanning line. Register 6 is a register for storing the comparison specified value code bit number.
The specified value is output as a register output 61 (FIG. 2f).

Comparator 5 changes the values of register output 41 and register output 61 from level %II to level %0# of line synchronization signal 13.
If the number of encoded bits of the previous scanning line≦the specified value is satisfied, the comparison result output 51 (Fig. 2g) is output, and 1 twin skip km is indicated for the image signal portion, and # instructs the special code generation circuit 7 to generate a code;
Simultaneously, image signal transfer request 11 7 level 1 to encoder 1
and start transferring the special code.

In Figure IIK2, when the level of the second line of the Hiro synchronization signal (Figure F82B) reaches 11# or %QI, the above conditions are satisfied and the comparison result output 51t- is output.

The special code generation path 1' is connected to the register 8 storing the special code, the data selector 9, and the counter 1° to '&
), the counter 10 is initialized upon receiving the output sl of the comparison @S, and the special code transfer request pulse 18 (II
2 h) IIc Therefore, the collar 7110 is operated, and the input of the data selector 90 is sequentially switched by its output 101, and the special code bit output 81 stored in the register 8 is output.
1) is supplied from the IK data selector output 91.

Encoder 1 outputs Oq# special code t as code data 14 (
1) in FIG. 2, and when the special code is sent out, the image signal transfer request 1it-level OKt is activated, and the encoding process of the next image signal starts.

Similarly, the number of code bits of the previous line is compared with the specified value, and if the result is equal or smaller, the current line is not coded and the Kl line is skipped, the K special code is sent, and the next line It encodes and then repeats the process for comparison.

Next, the receiving side will be explained. In FIG. 3, 21 is a decoder, 22 is a special code detection circuit, 23 is a shift register, 24 is a comparator, and 25 is a register storing the special code. To explain using the time chart in FIG. The detection circuit 22 starts operating at the same time.

The decoder 21 is made to have a processing speed sufficiently faster than the code sending speed of the normal line section, and the code sampling pulse 27
Accordingly, the encoded data is decoded as it is received, and a K facsimile image signal is outputted along with a line synchronization code 29 (FIG. 4f) for identifying one line and a single signal output 28 (FIG. 4e). .

The special code detection circuit 22 similarly takes in data 261 to the shift register 23 in accordance with the code sampling link pulse 27. The output of the shift register 23 is supplied to the comparator 24 as a shift register output 231.
is compared with the output 251 of the special code storage register 25,
It operates to output the result as a comparison output 241. Therefore, the special code detection circuit 22 operates simultaneously with the decoder 21 and waits until the shift register 22 detects the special code.
Drawn to 3 1#t-) Day! Discard sequentially.

When a special code is detected, the comparator output 241f Nirepel O
The level IK is performed from then on, and the recording unit is instructed to skip one line, and since the decoder 21 also performs decoding at the same time, the decoder 21 is also instructed to abort the decoding operation and is initialized.

After initialization, the decoder 21 starts decoding the next code, and at the same time the special code detection tB circuit 22 also operates to detect the next special code.

Similarly, each time a special code is detected, the linear density can be automatically switched by instructing the recording unit to skip one line. Also, at this time, if the decoder 21 or the expansion sickle unit has a memory for storing the factor ξ image signal, the l line ski 7
Alternatively, you can instruct the facsimile image signal of the previous line to be written twice (instead of skipping one line, write the previous line again), and it is also possible to control the facsimile image signal to obtain good image quality. be.

As explained above, according to the present invention, by making use of the functions of an encoder and a decoder, the circuit configuration is simple, and an accurate amount of information can be determined for each scanning line.

[Brief explanation of drawings]

111 and 3 are block diagrams of the transmitting side and the receiving side showing an embodiment of the present invention, and FIGS. 2 and 4 are waveform diagrams showing the operation of each part in the gi diagram and FIG. 3. l...Encoder, 2...-information amount determination circuit,
3, 10...Counter, 4.6.8---Register, 5---Comparator, 5---Selector, F---Special code generation circuit, 21...Decoder, 22---411 special code detection circuit, 23...
...Shift register, 24...-Comparator, 25.
−・・−・1st episode 5 Figure

Claims (1)

[Claims] A means for encoding an image signal obtained by scanning an original image along a scanning line in the horizontal direction, a counting circuit for counting the amount of encoded information per line, and a means for determining whether a specified value has been exceeded. It consists of a circuit for determining the amount of information, and a number of bits that do not exist in the O code format when encoding both signals and are smaller than the specified number of bits for determining the amount of encoded information for one line. a circuit for generating a special code according to the judgment value, and a circuit for detecting the special code, predicts the amount of information of the next line according to the amount of encoded information of the l line, and switches the scanning line to the other. An automatic line density switching method for facsimile machines that controls the te characteristic.