JPS6258589B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for transmitting color image information, particularly,
For example, the present invention relates to a color facsimile signal transmission system in which document image information in three colors such as white, black, and red is converted into amplitude and phase information and then transmitted electronically.

Conventional facsimile transmission systems include one that transmits normal black and white binary document image information and one that transmits color information, but systems that transmit complete color information require complicated and expensive equipment.

On the other hand, when using facsimile, it is often desirable to electronically send black and white calligraphy and paintings with handwriting errors or stamps added as is.

For this purpose, the following method can be considered, for example, in accordance with the conventional AM-PM transmission facsimile (CCTTI G standard). In other words, the amplitude of white (ground color) information is zero, and the information of black, red,
This is a method (hereinafter referred to as black-red modulation method) in which the information is transmitted by phase modulating the carrier waves so that they are O-phase and π-phase, respectively.

However, in this facsimile transmission method (black-red modulation method), this is received by a normal receiver, that is, a receiver that receives and reproduces signals in which the white of the G standard is alternately changed in O phase and π phase. Then white,
The drawback is that the blacks are reversed, making it look like a negative photograph.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to realize a system for transmitting facsimile signals of three-color image information that can be received by a conventional G-standard receiver while still maintaining the band compression effect.

In order to achieve the above-mentioned object, the present invention provides a system for transmitting three-color document image signals of a ground color (e.g., white) and two other colors (e.g., black and red) by an AM-PM-VSB system. The ground color signal generated between the two colors is phase modulated, and the phase is controlled by the state of the other two colors.

The present invention will be explained in detail below using the drawings. Figures 1 and 2 show the calligraphy and drawings to be transmitted (Fig. 1) in order to explain the principle of the present invention, and a and , signal b in a method of transmitting a black-red color signal using a conventionally known black-red modulation method.
FIG. 3 is an explanatory diagram showing the relationship between the transmission signal c and the transmission signal c in the color image signal transmission system according to the embodiment of the present invention.

When scanning a paper surface 1 with 2 black and 3 red patterns on a white background as shown in Figure 1 with scanning line 4, the conventional G
The transmission signal according to the standard method is as shown in FIG. 2a. In other words, the white part is a carrier wave with a constant amplitude (the standard also allows the amplitude to be modulated according to the brightness), and the black and red parts are carrier waves with zero amplitude, and the white part is a carrier wave. The phases of are alternately O phase (positive phase) and π phase (negative phase). In this case, red and black cannot be distinguished during playback, but the narrowband characteristics are maintained as is the purpose of the standard determination.

In the conventional black-red modulation system shown in Fig. 2b, which allows the two colors of black and red to be distinguished, the phase of the carrier wave is O phase in the black part, π phase in the red part, and π phase in the white part. The amplitude is set to zero. Therefore, a receiver configured to receive a signal such as a has a drawback that when a signal such as b is received, the white (ground color) and black and red parts are reversed. Furthermore, if the same color occurs continuously, the phase of the carrier wave does not change alternately, resulting in a broadband signal.

In the embodiment of the transmission system of the present invention, as shown in FIG. 2c, the carrier wave is sent only for the white portion, and when only black or red is continuous, modulation is performed based on the same principle as in a.

In other words, the phase of the carrier wave in the white part is alternately O.
It is modulated so that the phase and π phase change. However, as shown in time domain 5, when the colors on both sides of the white part are different, the above rules are followed, namely O, π, O, π...
The regularity of alternating phases is intentionally disrupted, and the same phase continues. On the receiving side, the following color is identified as red or black based on the sequence of phases.

Next, the configuration of the circuit for obtaining the above signal will be described. Figure 3 shows the conventional AM-PM method (Figure 2a
This is an example of a configuration method for obtaining a signal. That is, the image data read by the sensor is once stored in the image memory 1 for one scanning line. Here, it is assumed that white = "0" and black or red = "1" are stored. This signal is applied to the low pass filter 2 via an inverter 9, ie with white=1.

On the other hand, this signal is also added to the change point detection section 3,
By delay flip-flop 4 and AND circuit 5,
The point of change from black 1 to white 0 is detected. At each detection, the flip-flop 6 is inverted from "0" to "1" or from "1" to "0". Based on this output, the output of the oscillator 7 is phase-modulated by a phase modulation circuit 8 and amplitude-modulated by an amplitude modulation circuit 9. and,
It is output through a filter 10. This output is shown in Figure 2a
become that way.

FIG. 4 shows an embodiment of a transmitting section that implements the color image signal transmission system according to the present invention.

First, the black and red signals B and R of one scanning line are detected by an optical system, and are detected by the memories 11 and 12, respectively.
is memorized. At this time, a red/black state memory 13 is placed at the same time, and each time black/red starts, it is memorized as whether it is red or black. However, 1 bit is allocated to the section where the red and black states continue. On the other hand, the OR output of the output of the black memory 11 and the output of the red memory 12 is added to the reduction filter 14.

Since the change point detection circuit 15 does not change the phase of the white signal when the next signal is black, the above-mentioned state memory 13
When the next output is red, that is, when the output of the state memory 13 is 0, the output of the AND gate 16 is prohibited and the inversion of the flip-flop T17 is prohibited. The outputs of the low-pass filter 14 and the change point detection circuit 15 are output to the amplitude modulation circuit 1 as shown in the figure.
8, filter 19, phase modulator 20 and oscillator 2
1 is added to the circuit consisting of 1. These circuit configurations are the amplitude modulator 9 and filter 1 shown in FIG.
0, the phase modulator 8 and the oscillator 7, and operate in the same way, so their explanation will be omitted.

As described above, according to this embodiment, when the same portion of black or red occurs successively, the white information in between is AM whose phase is alternately changed.
-PM signal, and if the color information on both sides of white is different, the signal shown in FIG. 2c is obtained without being changed. The configuration of the receiving section can be easily realized from a conventional device based on the above-mentioned principle. That is, when modulated waves corresponding to the ground color continue to have the same phase, it can be detected that the next color signal is different from the previous color signal.

Although the system of the present invention has been described above using one embodiment, the present invention is not limited to the above embodiment, and various embodiments as described below can be realized.

(1) Based on the phase signal, set the white signal before black to O
In phase, white signal before red in π phase (or vice versa)
Modulate.

(2) Based on the phase signal, the white signal after black is O
In phase, add the white signal after red in π phase (or the reversed output).

(3) In both black and red cases, following the conventional rules for sending only the black signal, the O-phase and π-phase are alternately modulated on the following white signals. However, only the first black color does not change its phase.

Note that when a black signal and a red signal are continuous without a white intervening signal, the color change between them cannot be transmitted, but in this case, a white signal is inserted figuratively between the black and red signals. This can be solved by

Note that in (1) and (2) above, when black or red is continuous, the phase does not change, so the excellent band compression characteristics of the AM-PM system are lost. On the other hand, in the basic method (the embodiment shown in Figure 2 c) and (3) above, the phase is reversed in the first signal when it changes from red to black or from black to red in between the white signal. Since there is no band compression, there is no band compression effect, but this effect appears after that. However, there is a problem that once a mistake is made, red and black will be reversed in that scanning line.

Although there are some advantages and disadvantages in each of the above methods, it is clear that they are much improved compared to the conventional method.

As described above, according to the present invention, facsimile information in three colors can be transmitted using an extremely simple method, which is extremely effective in practical use.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a part of a document image to be transmitted, FIG. 2 is an explanatory diagram of facsimile signals according to the conventional and embodiments of the present invention to explain the operation of the present invention, and FIG. 3 is a diagram showing a conventional facsimile signal. Fig. 4 is a diagram showing the main part of a facsimile machine according to an embodiment of the present invention. 11, 12, 13...Memory, 14...Low pass filter, 15...Change point detection circuit, 16...AND gate, 17...Flip-flop circuit, 18...
...amplitude modulator, 19...filter, 20...phase modulator, 21...oscillator.

Claims (1)

[Claims] 1. AM that electrically transmits calligraphy image signals in three colors including the background color
- A color image information transmission system characterized in that, in the PM transmission system, the document image signals of the three colors are transmitted by controlling the phase of one color according to the state of the other two colors. 2. A color image information transmission method according to item 1, wherein one color whose phase is controlled corresponds to the background color of a book image. 3 In the method described in item 1, if both sides of the above one color are the same as the other two colors, the phase of the carrier wave corresponding to one color is alternately reversed, and both sides of the above one color are the same as the other two colors. A color image information transmission system characterized in that when two colors are different, the phases of carrier waves corresponding to one color are controlled so that they are in the same phase. 4. In the transmission method described in item 1, the phase of the one color is controlled so that it becomes 0 phase after the other two colors, the first color, and π phase after the second color. A color image information transmission method characterized by: 5. A color characterized in that, in the transmission method according to item 1, when two colors other than the first color change, the phase of the first color following the changed color is controlled so that they are in phase. Image information transmission method.