JPS6031420B2 - Image signal processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image signal processing method in a device such as a facsimile that transmits two-dimensional image information.

Image information transmission devices such as facsimiles are partly based on photographic technology, but most are based on so-called hard copy recording, in which images are reproduced on paper and received and recorded. Thermal recording method, electrostatic recording method, discharge recording method, electrolytic recording method, etc. are used.

One characteristic common to these recording methods is that a large portion of the energy required for recording is spent in recording the black information portion.

Therefore, the conventional facsimile apparatus has a disadvantage in that power consumption increases significantly when the image information to be transmitted has many black parts. In addition, thermal recording methods have the disadvantage that the increased power consumption causes the temperature of the entire recording head to rise, making it impossible to continue recording and shortening the life of the recording head. was occurring.

Furthermore, when using the electrostatic recording method, toner consumption increases in proportion to the increase in the black information area, and when a flash fixing method is used, the increase in fixing power cannot be ignored. Ta.

Furthermore, when the discharge recording method was used, there was a drawback in that the more 5-black information areas there were, the more paper waste was generated as a result of recording.

When the electrolytic recording method is adopted, the disadvantage is that increasing the black information portion causes the recorder to wear out more quickly, resulting in a shorter replacement period.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image signal processing method for facsimile machines, etc., which eliminates the drawbacks of the prior art described above and prevents the power consumption required for recording from increasing significantly even if the original image information contains a large amount of black information. It is on offer. In order to achieve this object, the present invention is characterized in that part of the black information is changed to white information without reducing the information recognition ability of the received and recorded screen.

First, prior to explaining the present invention, the general configuration of an image information transmission apparatus such as a facsimile machine to which the present invention is applied will be explained with reference to FIG. In the figure, 1 is a document, 2 is an optical system such as lenses, 3 is a photoelectric converter, 4 is an amplifier, 5 is a comparator, 6 is a comparison voltage generator, 7 is a transmission system, 8 is a recording drive device, 9 1 is a recording needle, and 10 is a recording paper. Next, to explain the operation using a facsimile machine as an example, the original 1 is scanned by mechanical scanning such as rotational scanning or plane scanning, or electrical main scanning by CCD or the like while feeding the original 1 in sub-scanning. A one-dimensional serial analog image signal is obtained from a photoelectric converter 3, amplified by an amplifier 4, and compared with a voltage from a comparison voltage generator 6 by a comparator 5, thereby obtaining a black and white 200 million digital image signal S.

This digital image signal S, for example, has a waveform as shown in FIG.

Then, this digital image signal S, is processed by a data compressor,
The signal is supplied to a recording drive device 8 on the receiving side through a transmission system 7 consisting of a modem, a transmission line, etc., and is received and recorded by a recording needle 9 scanning a recording sheet 10, thereby reproducing the image.

Note that the recorder 9 is used for discharge recording or electrolytic recording, but it goes without saying that for other recording methods, a thermal head or a multi-stylus electrode triode may be used depending on the recording method.

Next, an embodiment of the image signal processing method according to the present invention will be described. In the present invention, the image signal processing circuit may be provided on either the transmitting side or the receiving side 4 of an image information transmission device such as a facsimile machine.

For example, FIG. 3 shows an embodiment provided on the transmitting side, and FIG. 4 shows an embodiment provided on the receiving side, in which numeral 11 is the image signal processing circuit of the present invention, and the other parts are as shown in FIG. 1. It is.

Next, an embodiment of the image signal processing circuit 11 according to the present invention will be described with reference to FIG.

In the figure, 12 is a 24-bit shift register (hereinafter referred to as S/R), 13 is a 24-input NAND gate, and 14 is a 24-bit shift register (hereinafter referred to as S/R).
is a 12-bit S/R, and 15 is an AND gate.

The S/R 12 receives the box signal S, (FIGS. 1 to 4) as input, and shifts the image signal S, using the 0 clock CL generated corresponding to the pixel of the image signal S,.

Therefore, a signal S4, which is delayed by 24 clocks from the image signal S, appears at the output of the S/R 12. Nand Gate 13 is S/
Since the output from each bit of R12 is input, the black part of the image signal S is 24 bits, that is, the number of black pixels is 24.
After that, the signal S2 is inputted to the S/R 12 and becomes 0 only when all of its bits are 1.

Since the S/R 14 inputs the signal S2 and is shifted by the clock CL, a signal S3 which is the signal S2 delayed by 12 clocks is generated at its output. The AND gate 15 receives a signal S,' representing the AND of the signals S4 and S3.
occurs in the output.

Next, the operation will be explained using the time chart shown in FIG.

In FIG. 6, the respective waveforms CL, S, , S2, S
3, S4, S,' represent signals at each part in FIG.

Assume that the image signal S, becomes 1, that is, black, at a time.

Assume that the black signals S and a have consecutive pixels of 24 bits or more. Then, when the clock CL is generated in 24 bits from the timer and the time reaches 1, the S
All bits of /R12 become 1.

Then, since all the inputs of the NAND gate 13 become 1, its output signal S2 falls and becomes 0. Since this signal S2 is applied to the input of the S/R14, when 12 bits of clock CL are generated from time t2, S
The output signal S3 of /R14 falls to 0. On the other hand, S/R
Since the signal S4, which is obtained by delaying the image signal S by 24 bits, appears at the output of No. 12, the signal S4 becomes 1 at the time.

Therefore, the output signal S,' of the AND gate 15 also becomes 1 at the time.
It has become. However, the signal S3 becomes 0 at time t3.
Therefore, the signal S,' also becomes 01 at the time. Eventually, at time t4, when the black signal S, a changes to 0, that is, white, the first bits of S/R 12 become 0 one after another, so the output signal S2 of the NAND gate 13 returns to 1. Since this signal S2 is delayed by 12 bits by the S/R 14 to become the signal S3, the signal S3 returns to 1 at a time when 12 bits have elapsed from time t4. On the other hand, S/R12 is 2
Since it is 4 bits, the signal S4 remains 1 at the time. Therefore, the output of the AND gate 15 becomes 1 again at this point. Z, that is, the signal S,' becomes 1 at time t5. In this way, when the time corresponding to 12 bits further passes and reaches time T6, the output signal S4 of the S/R 12 also becomes 0, and the output signal S,' of the AND gate 15 also becomes 0. In this way, when a black signal having a length of 24 bits or more Z, for example S, a, appears consecutively in the image signal S, the signal S. As shown as S and a' in ', only the beginning part of the black signal, the part from time ratio 2 to t3, and the end part, the part from time t5 to t6 are left, and the central part and time ratio are From gadfly 3 to t5
The part is converted to 0, that is, a black signal which is converted into a white signal by pupil 2.

On the other hand, for a black signal whose continuous length does not reach 24 bits, such as the black signal S and b in the signal S, all bits of S/R12 may become 1. Therefore, the output signal S2 of the NAND gate 13 does not become 0,
Therefore, since 0 does not appear in the output signal S3 of the S/R 14, the output signal S4 of the S/R 12 appears as it is at the output of the AND gate 15, and the black signal S, remains in the signal S,'. Become.

As is clear from the above explanation, it is important to determine whether the operation according to the present invention is performed on only those black signals whose number of consecutive pixels exceeds the number of bits among the black signals contained in the image signal S. It can be seen that it is determined by the number of bits of /R12.

That is, in the above embodiment, the number of bits of S/R12 is set to 24.
Therefore, it operates only on black signals with a length of 24 bits or more, and the central part thereof is replaced with a white signal. Also, on the same machine, the number of bits of S/R14 is
It is necessary to select half the number of bits of R,2, so that only the first 12 bits and the last 12 bits of the black signal of 24 bits or more, for example, the black signal S,a', are selected.
In other words, it is possible to leave the same number of bits in the front and rear parts.

Of course, if necessary, change the number of bits of S/R14 to S/R1.
The number of bits may be increased or decreased from half of the number of bits of 2. In this case, if the number of bits is increased, the part before the black signal becomes longer and the part after it becomes shorter. And it goes without saying that reducing it will have the opposite effect.
In this embodiment, all output signals S,' are delayed by 24 bits, but those skilled in the art can easily understand that this does not cause any particular problem in recording processing.

．． Next, the effect when the image signal S, is converted into the image signal S,' and recorded by the processing circuit 11 will be explained.

In Figure 7, A is the original picture drawn on the manuscript,
B is an image received, recorded, and reproduced using the image signal S,' obtained by the image signal processing circuit 11 shown in FIG.

Note that C will be described later. As is clear from B, according to this embodiment, even if there is a portion filled in black on the original screen, that portion is recorded and reproduced in a white state with only the outline remaining.

Generally speaking, in facsimiles, most of the screen to be transmitted consists of characters and figures, and the image signal is a binary digital signal of 5 black and white, so the screen is filled with black. In many cases, the information provided by these parts is of little value. Therefore, it can be considered that there is almost no loss of information due to whitening out of the black portion of the original image as shown in FIG. 7B. In this manner, according to the embodiment of the present invention, most of the black information recorded on the recording paper surface can be removed with almost no effect on the amount of information contained in the document. Next, FIG. 8 shows another embodiment of the present invention, in which the same or equivalent parts as in the embodiment shown in FIG. 5 are given the same reference numerals. In the figure, 16 is a T-flip-flop (hereinafter referred to as TFF).
, 17 is the or gate.

Next, the operation will be explained using the time chart shown in FIG. The TFF 16 is driven by the clock CL, generates a signal S5 obtained by dividing the frequency of the clock CL, and outputs the signal S5 to the OR gate 17.
, and when there is no signal S3 from S/RI'4, a signal S6 containing the signal S5 is produced at the output of the OR gate 17.

Therefore, the inputs of the AND gate 15 are the signal S4 from the S/R 12 and the signal S6 from the OR gate 17, and the signal S,' appearing at its output is a white signal in the center of the bad signal, as in the case of FIG. instead of being replaced by T
It has a black pixel reduction section in the center, which is alternately and periodically replaced with a white signal by the signal from the FF 16.

As a result, the received screen recorded using the image signals S,' according to the embodiment of FIG. 8 looks like C in FIG. It will be played back as an image filled with dots.

Therefore, according to this embodiment, it is possible to perform recording by removing a considerable portion of the black signal while retaining the characteristics of the original screen.

In any of the above embodiments, it goes without saying that the thickness of the outline of the black image portion can be arbitrarily determined by the number of bits of S/R12.

As explained above, according to the present invention, the amount of energy required for recording can be effectively reduced without significantly reducing the information content of the original image to be transmitted. It is possible to provide an image signal processing method that has a small amount of noise and can eliminate various drawbacks of the various recording methods described above.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an example of the general configuration of an image information transmission device such as a facsimile machine, Fig. 2 is a waveform diagram showing an example of an image signal, and Figs. 3 and 4 are when the present invention is applied. 5 is a circuit diagram showing an embodiment of the signal processing circuit in the image signal processing method according to the present invention, FIG. 6 is a time chart for explaining its operation, and FIG. 7 is a diagram showing the effects of the present invention. FIG. 8 is a circuit diagram showing another embodiment of the present invention, and FIG. 9 is a time chart for explaining its operation. 1 1... Signal processing circuit, 12... Shift register, 13... NAND gate, 14... Shift register, 15... AND gate, 16... T-flip-flop, 17... OR gate. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 8 Figure 7 Figure 9

Claims (1)

[Claims] 1. A method for processing a one-dimensional serial image signal obtained by scanning two-dimensional image information, comprising: a first shift register that receives the one-dimensional serial image signal as data input; When a predetermined number of consecutive parallel bit outputs are input, a NAND gate is provided, a second shift register whose data input is the output of this NAND gate, and an AND gate whose inputs are the outputs of these first and second shift registers. From the output of the AND gate, for each piece of black information included in the one-dimensional serial image signal whose number of pixels exceeds a predetermined value, a predetermined image portion at the beginning and end of the black information is determined. 1. An image signal processing method characterized in that the image signal processing method is configured to obtain a one-dimensional serial image signal for hard copy recording in which at least a part of the intermediate portion excluding the white information is converted to white information. 2. The signal processing method according to claim 1, wherein the intermediate portion of the black information is continuously converted into white information. 3. The signal processing method according to claim 1, wherein the intermediate portion of the black information is periodically converted to white information.