JP2653490B2 - Image data encoding / decoding method and facsimile apparatus - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for encoding / decoding image data and a facsimile apparatus, and more particularly to an encoding / decoding method for superimposing / separating other data on image data. The present invention relates to a decoding method and a facsimile apparatus to which the method is applied.

[Prior art] Conventionally, in order to make recording and transmission of image data more efficient,
A technique of encoding and compressing image data is employed. For example, a Modified Huffman (MH) method is known which binarizes an image into black and white and converts a continuous number of binarized pixels (run length) into a predetermined code according to the frequency of occurrence. I have. At the time of decoding, a run length is obtained from this code to restore an image.

Such encoding / decoding methods of image data are widely used in facsimile apparatuses.

[Problems to be Solved by the Invention] However, since such an encoding method is a known method, even if the data is recorded in a compressed form or is being transmitted in a compressed form, the encoding method can be easily performed. There was a problem of being decrypted. In addition, when used as a facsimile machine, since it is restored to a form that can be recognized by anyone, it cannot be concealed from an intervening person such as a document clerk. That is, in the conventional encoding / decoding method, it can be said that information security is hardly considered.

To solve such a problem, a method of encrypting data using a key, which is a multi-digit numerical value, has been proposed. However, since it is apparent at first glance that the data is encrypted, it cannot be decrypted enough. Is not considered a realistic solution. A method of combining data to be concealed with other data (dummy data) and encrypting the data is also conceivable. However, in this case, the data capacity becomes large, and the data to be concealed in the normal MH method is used. And dummy data cannot be decrypted.

The present invention solves the above problems, within the framework of a normal MH system,
Another object of the present invention is to combine image data with other data to realize data recording or transmission density improvement and data concealment associated therewith.

Configuration of the Invention The configuration of the present invention that achieves the above object will be described below.

[Means for Solving the Problems] As a method of combining other data with image data or separating the combined other data from image data, there are the method inventions according to claims 1 and 2.

That is, the present invention according to claim 1 for synthesizing image data with other data and encoding the image data, calculates a run length of a pixel on a scanning line from image data obtained by binarizing each pixel of an original image. In the image data encoding method of sequentially detecting, encoding the run length and compressing the image data, every time the run length is detected, another binary data to be combined with the image data is read out. According to the read binary data, when the binary data is the first value, the run length becomes an even number, and when the binary data is the second value opposite to the first value, By correcting the detected run length within one pixel so that the run length becomes an odd number, the read binary data is combined with the detected run length, and the binary data is combined. Encoding the run length after, it is summarized as method of encoding image data according to claim.

The present invention according to claim 2 for restoring an image and separating other data from the image data encoded by this encoding method, uses the encoding method according to claim 1. Decoding the decoded image data, extracting the run length of the pixel, and restoring the image according to the extracted run length. If the extracted run length is an even number, the run length It is determined that the other binary data that is the first value is synthesized, and if the extracted run length is an odd number, the other binary data that is the second value is included in the run length. Determining that the image data has been synthesized and separating the other binary data from the image data.

On the other hand, a facsimile apparatus according to claims 3 and 4 is an apparatus that directly performs the above-described image data encoding method and image data decoding method.

That is, a facsimile apparatus according to claim 3, which directly implements the encoding method according to claim 1, reads out an image written on a document by binarization, and reads the image binarized by the reading means. Run length detecting means for sequentially detecting run lengths of pixels on a scanning line from the obtained image data; coding means for coding the run length detected by the run length detecting means to compress the image data; Transmitting means for outputting the image data compressed by the encoding means to the communication line in a predetermined procedure; anda facsimile apparatus comprising: a combined data setting means for preparing other binary data to be combined with the image data; Each time the run length is detected by the run length detecting means, the binary data prepared by the synthetic data setting means is read out; According to the read binary data, when the binary data is the first value, the run length becomes an even number, and when the binary data is the second value opposite to the first value, Run length correcting means for correcting the detected run length within one pixel so that the read binary data is combined with the detected run length so that the run length becomes an odd number. The encoding unit is configured to encode a run length after the binary data has been combined by the run length correction unit.

A facsimile apparatus according to claim 4, which directly implements the encoding method according to claim 2, wherein receiving means for receiving, via a communication line, image data transmitted from the facsimile apparatus according to claim 3. A run-length extracting unit that decodes image data received by the receiving unit to extract a run-length of a pixel; an image reproducing unit that reproduces an image according to the run-length extracted by the run-length extracting unit; If the run length extracted by the run length extracting means is an even number, it is determined that the other binary data that is the first value is combined with the run length. If the extracted run length is an odd number, it is determined that the other binary data as the second value is combined with the run length. Te, a data separating means for separating said other binary data from the image data, is characterized by comprising a data output means for outputting the binary data separated by the data separating means.

[Operation] According to the image data encoding / decoding method of the present invention having the above configuration, the image data is handled as follows.

First, in the image data encoding method according to the first aspect, image data obtained by binarizing each pixel of an original image is obtained by:
Image data is compressed by a so-called Modified Huffman (MH) method that sequentially detects run lengths of pixels on a scanning line and encodes the detected run lengths.
Each time a run length to be encoded is detected from the image data, another binary data to be combined with the image data is read out, and the binary data is combined with the image data according to the following procedure.

That is, according to the read binary data, when the binary data is the first value, the run length becomes an even number, and when the read binary data is the second value opposite to the first value. In this case, the read binary data is combined with the detected run length by correcting the detected run length within one pixel so that the run length becomes an odd number. Then, by encoding the run length after synthesizing the binary data in this way,
When encoding and compressing the original image data, other binary data is synthesized.

For example, when the binary data to be combined is “1” as the second value, if the run length is an even number, the run length is shortened by the value 1 and its parallelism (ie, , Even or odd) to odd,
If the run length is odd, the run length is left unchanged. On the other hand, when the binary data to be synthesized is “0” as the first value, if the run length is even, the run length is left unchanged without modification, and if the run length is odd, the run length is lengthened by one. To make the oddity even.

Then, the combined binary data can be separated from the image data in which the binary data has been combined in the above procedure by the image data decoding method according to the second aspect.

That is, in the image data decoding method according to the second aspect, the image data encoded by the encoding method according to the first aspect is decoded to extract the run length of the pixel,
The image is restored according to the extracted run length. Every time the run length is extracted, other binary data is separated by the following procedure.

That is, if the extracted run length is an even number, it is determined that another binary data that is the first value is combined with the run length, and if the extracted run length is an odd number, the run length is determined to be the same. The other binary data, which is the second value, is determined to be synthesized, and the other binary data is sequentially separated from the image data.

For example, when binary data is combined with image data by the method of the above-described specific example, if the extracted run length is an even number, a value of “0 =
It is determined that the binary data having the “first value” is synthesized, and if the extracted run length is an odd number, the binary data having the value “1 = second value” is synthesized with the run length. That is, the other binary data can be sequentially separated from the image data.

On the other hand, in the facsimile apparatus according to the third aspect of the present invention, wherein the encoding method according to the first aspect is directly implemented, the reading means reads the image written on the document by binarization, and the run-length detecting means reads the image. The run lengths of the pixels on the scanning lines are sequentially detected from the image data read by binarization by the means. Then, the encoding unit encodes the run length detected by the run length detection unit to compress the image data, and the transmission unit outputs the image data compressed by the encoding unit to the communication line in a predetermined procedure. .

Here, in particular, in the facsimile apparatus according to the third aspect, the combined data setting means prepares another binary data to be combined with the image data, and the run length correcting means detects the run length by the run length detecting means. Each time, the binary data prepared by the composite data setting means is read, and according to the read binary data, if the binary data is the first value, the run length becomes an even number, When the binary data is a second value opposite to the first value, the run length is odd.
The read binary data is combined with the detected run length by correcting the detected run length within one pixel. Then, the encoding means encodes the run length after the binary data has been synthesized by the run length correction means.

In other words, in the facsimile apparatus according to the third aspect, when the run-length correcting means and the encoding means function as described above, other binary data is synthesized when encoding and compressing the image data. .

Further, in the facsimile apparatus according to claim 4 for directly executing the encoding method according to claim 2, the receiving means transmits image data transmitted from the facsimile apparatus according to claim 3 via a communication line. The run length extracting means decodes the image data received by the receiving means and extracts the run length of the pixel. Then, the image reproducing means reproduces the image according to the run length extracted by the run length extracting means.

Here, in particular, in the facsimile apparatus according to claim 4, when the run length extracted by the run length extracting means is an even number, the other binary data having the first value in the run length is used. Is determined to be combined, and if the run length extracted by the run length extraction means is an odd number, it is determined that another binary data, which is the second value, is combined with the run length. Separate the other binary data from the received image data. Then, the output means outputs the binary data separated by the data separation means.

That is, in the facsimile apparatus according to the fourth aspect, when the data separating means functions as described above, when decoding the image data and reproducing the image, other binary data is sequentially separated from the image data. Because

[Embodiment] In order to further clarify the configuration and operation of the present invention described above, a preferred embodiment of an image data encoding / decoding method of the present invention and a facsimile apparatus which directly implements the method will be described below. I do. FIG. 1 is a schematic configuration diagram of two facsimile apparatuses as an embodiment connected via a communication line. Since the two facsimile apparatuses have both functions of transmission and reception and have the same internal configuration, the configuration of the facsimile apparatus 1 serving as the transmission side will be mainly described here.

In the facsimile apparatus 1, an image scanner 5 for image input and a printer 7 for image output are connected to a computer 3 having a terminal 2, and a board-type facsimile modem 10 is incorporated. Inside the computer 3, in addition to the well-known CPU 11, ROM 12, RAM 13,
A terminal controller 15 for inputting and outputting data to and from the scanner, a scanner input port 17 connected to the image scanner 5 and inputting the data, and a printer control port 18 connected to the printer 7 and outputting data are provided. The configuration of the facsimile machine 21 serving as the receiving side is the same as that of the facsimile machine 1, and the terminal 22, the computer 23, the image scanner 25, the printer 27, and the facsimile modem 30 are also provided. Both facsimile devices 1, 21 are connected to a public communication line 40 via built-in facsimile modems 10, 30.
It is connected to the.

Next, data combining / output processing and data receiving / separating processing in both facsimile apparatuses 1 and 21 will be described. FIG. 2 is a flowchart showing a processing routine executed by the facsimile machine 1 on the transmitting side, and FIG. 3 is a flowchart showing a processing routine executed by the facsimile apparatus 21 on the receiving side. In the following description, as shown in FIG. 4, among the arrangement of pixels on a scanning line, the first pixel of a continuous arrangement of black or white of a pixel to be transmitted is an, then white or black. The pixel in which the arrangement of pixels is inverted is an + 1, and the next pixel to be inverted in black and white is an + 2,
Call as.

The facsimile machine 1 on the transmitting side includes an image scanner 5
The original 51 to be transmitted is read, and the image data is expanded in the RAM 13 in advance. The image data of the document 51 is developed for each scanning line. The data to be combined with the data is input from the terminal 2 in the form of a character string, and is developed and stored in the RAM 13 in the computer 3.

The facsimile machine 1 on the transmitting side performs the call setting phase A
When the connection is made to the facsimile machine 21 on the receiving side via the communication line 40 via the communication line 40, the phase B prior to the message transmission is completed, and then the process proceeds to the phase C for transmitting the message. In the phase C, first, an end-of-line EOL is output as the start of a page, and a process of initializing a variable n used for cutting out a run length to a value 0 is performed (step 100).

Next, the first pixel on the scanning line is read, and as shown in FIG. 4, this is set as pixel an (step 105), and it is determined whether or not this pixel is a black pixel (step 11).
0). Since the terminating code and the makeup code for transmission in the facsimile apparatus include a white consecutive codeword and a black consecutive codeword, here, it is assumed that starting from the white consecutive codeword, the first pixel is a black pixel. Only in this case, a process of outputting a code indicating that the run length RL of the white pixel is 0 via the communication line 40 is performed (step 115).

Thereafter, a process of detecting a pixel an + 1, an + 2 in which the arrangement of the next white or black pixel is reversed on the scanning line is performed (step 120), and a run length R from the pixel an to the pixel an + 1 is obtained.
It is determined whether L (anan + 1) is an even number (step 125). This is because, in the present embodiment, the character string Dm is superimposed on the image data of the document 51 by paying attention to the oddness of the run length RL of the pixel (that is, whether the run length RL is even or odd). .

If the run length RL (anan + 1) is an even number, it is determined whether or not the run length RL (anan + 1) is equal to or greater than 4 (step 130), while the run length RL (anan + 1) is an odd number. In this case, it is determined whether or not the run length RL (an + 1) is equal to or greater than 3 and the run length RL (an + 1an + 2) is equal to or greater than 2 (steps 133 and 136). These determinations (steps 130, 133, and 136) are based on the fact that data cannot be restored by combining one bit of data depending on the arrangement of pixels. This condition will be described in detail together with a description of a method of synthesizing data.

If the condition of the run length RL is satisfied, the character strings Dm to be synthesized are sequentially read, and the i-th bit (hereinafter, this bit is represented as a bit Dm (i)) is read (steps 140 and 145). If RL (anan + 1) is an even number, it is determined whether or not the bit Dm (i) has the value 1 (step 150), while the run length RL (anan +
If 1) is an odd number, it is determined whether or not the bit Dm (i) is 0 (step 155). If the run length RL (anan + 1) is even and the bit Dm (i) is 1, the pixel an + 1 is moved one pixel forward (step 160), while the run length RL (anan + 1)
Is odd and the bit Dm (i) has the value 0, the pixel a
n + 1 is moved backward by one pixel (step 165). Note that the run length RL (anan + 1) is an even number and the bit Dm (i)
Is zero, or when the run length RL (anan + 1) is odd and the bit Dm (i) is one, no change is made to the run length RL (anan + 1).

FIGS. 5 and 6 show the state of such data synthesis. As shown in FIG. 5 (A), the run length RL (a
If (nan + 1) is the value 6 (even number) and the bit Dm (i) of the character string Dm to be synthesized is the value 0, the run length is not changed (FIG. 5 (B)), but the bit Dm (i) If the value is 1, the pixel an + 1 is moved one pixel before as shown in FIG. 5C (step 160). FIG. 6 (A)
As shown in the figure, when the run length RL (anan + 1) of the black pixel is a value 5 (odd number), the bit Dm of the character string Dm to be synthesized is
When (i) is 0, as shown in FIG.
The pixel an + 1 is shifted backward by one pixel (step 165), and if the bit Dm (i) has the value 1, the run length is not changed (FIG. 6 (C)).

Thus, in this embodiment, the character string to be synthesized is
If the bit Dm (i) of Dm is bit 1, the combined run length is odd, while if the bit Dm (i) is bit 0, the combined run length is even. Then, the run length of the image data is set and the two data are combined. At this time, the run length of the image data to be combined is limited to a certain limit (steps 130, 133, 13).
6) exists. For example, as shown in FIG. 7, the run length RL (an + 1) is an odd number and the run length RL (an +
When 1an + 2) has the value 1, if the pixel an + 1 is improperly moved backward by one pixel, the white pixel disappears and the preceding and succeeding black pixels are continuously connected. As a result, at the time of decoding, only one run length can be extracted, and in such a case, data cannot be synthesized. Therefore, if the focused run length RL (anan + 1) is an odd number, the run length RL
(An + 1an + 2) ≧ 2. By the way, when the data is synthesized under this condition, as shown in FIG. 8, when the run length of interest is shifted to the next pixel, assuming that data cannot be synthesized in the run length RL (anan + 1), The run length RL (an + 1an + 2) has a value of 2, and it may be determined at decoding time that bit 0 is synthesized as shown in FIG.
Therefore, the condition of the run length for synthesizing the data must be RL (an + 1 + 1) ≧ 3 and RL (an + 1an + 2) ≧ 2.

On the other hand, the run length RL (anan)
When +1) is an even number, as shown in FIG. 9, if the data to be combined is bit 1, the data moves forward by one pixel.
At the time of decoding, it is determined that the data is not synthesized even though the data is synthesized. Therefore, when the run length is an even number, the condition of the run length must be RL (anan + 1) ≧ 4. These conditions correspond to steps 130 and 13
This corresponds to 3,136 decisions.

Assuming that the 1-bit information of the character string Dm is superimposed on the image data by the above processing, the read variable i of 0 to 7 bits of the character string Dm is incremented by 1 (step 170). If the run-length condition is not satisfied (steps 130, 133, 136), data synthesis or variable i
Is not incremented.

After the above process, a process of encoding the run length RL (anan + 1) and transmitting it through the facsimile modem 10 is performed (step 180). Thereafter, the variable n is incremented by 1 to advance the run length of interest on the scanning line by one (step 190), and it is determined whether one scanning line has been completed (step 200).
If one line has not been completed, the process returns to step 120, and the above-described processing is repeated from the detection of a change point next to continuous white or black pixels. If one line has been completed, it is determined whether one page has been completed (step 210). If one page has not been completed, the process returns to step 100, and the above-described processing is performed based on the output of EOL and the initialization of the variable n. Repeat the process. When one page is completed, the code RT which is a page end signal is used.
C is output (step 220), and then the process exits to "NEXT" and proceeds to the processing of phase D. When transmitting data of a plurality of pages, the process returns from the phase D to the phase C again, and executes the processing shown in FIG. 2 again.

On the other hand, the facsimile machine 21 for reception transmits the communication line 40 to the facsimile machine 1 on the transmitting side through the call setting phase A.
, Completes phase B prior to message transmission / reception, and then moves to phase C for receiving a message. In the phase C, as shown in FIG. 3, first, a process of inputting a code received through the facsimile modem 30 is performed (step 300), and whether the received code is the code EOL indicating the start of the scanning line is determined. It is determined whether or not it is (step 310). At the start of a page or a scan line, the code EOL is transmitted. In this case, a variable n is initialized to a value of 0 (step 320), and a code for causing the printer 27 to perform a line feed for one scan line is provided. Output (step 330). Thereafter, it is determined whether or not the end of the page has been reached (step 340). If the end of the page has not been reached, the above processing is repeated from the input of the code (step 300). At the end of the page, exit to "NEXT"
The process proceeds to a phase D process. When transmitting data of a plurality of pages, the process returns from phase D to phase C again, and executes the processing shown in FIG. 3 again.

If the received code is not EOL (steps 300 and 310),
Pixel run length RL (anan + 1) from received code
Is performed (step 350), and it is determined whether the condition for separating the data superimposed on the decoded run length RL (anan + 1) is satisfied (step 360). These conditions correspond to the conditions at the time of combination described in the facsimile machine 1 for transmission (steps 130, 133, and 136 in FIG. 2).

If the condition for separating data is satisfied, the run length RL (anan + 1) of interest is then set to an even number (even).
Is determined (step 370), and if it is an even number, the bit Dm (i) is set to a value of 0 (step 38).
0) If it is odd, the bit Dm (i) is set to the value 1 (step 385). Then, assuming that one bit of the data is separated, the variable i indicating the number of bits is incremented by 1 (step 390). The variable m is incremented each time 8 bits are separated, and a new character Dm is decoded. The reason for not initializing this variable m in the routine shown in FIG. 3 is that the synthesized character string Dm is
This is because the image data may cover a plurality of pages.

After the bit Dm (i) of the data is separated in this way, or when the separation condition is not satisfied, the run length RL
The image data is output according to (anan + 1) and the printer 27
To print an image (step 400). Then, the variable n
Is incremented by 1 and the above-described processing is repeated from the input of the code (step 300).

Through the above processing, the receiving facsimile machine 21 that has received the data prints the image on the document 51 on the printer 27. Fig. 10 (A) shows the high resolution mode (7.7 lines / mm)
FIG. 10B is a diagram illustrating a part of a received image when only the first document is transmitted, and FIG. 10B is a diagram illustrating a received image when data input from the terminal 2 is combined with the document 51 and transmitted. It is explanatory drawing which shows a part. As shown in the figure, the image is slightly rough due to the fact that the change point of the pixel is shifted by one bit due to the combination of the data, but the quality is not so much a problem. Also, as far as FIG. 10 (B) is concerned, there is no possibility that it is known that data has been synthesized with this image, and the confidentiality of the data is extremely high.

FIGS. 11A and 11B are explanatory diagrams showing an example of data synthesis using other images. Table 1 shows the amount of data that can be combined and the amount of coded data transmitted in these transmission experiments. Documents 1 and 2 shown in Table 1 are partially shown in FIGS. 10 and 11. Also, the originals 4 and 7 are photographic / picture originals, and the amount of data that can be combined is large compared to a document. From these results, when an A4-size original (1728 x 2376 pixels) is transmitted by facsimile, data of thousands of characters can be synthesized in the examples shown in Figs. 10 and 11; It can be seen that character data can be synthesized. Moreover,
The amount of information to be transmitted hardly increases due to the combination of such data, and may be even reduced.

Next, the process of extracting the data Dm extracted by the process shown in FIG. 3 and stored in the internal RAM of the facsimile machine 21 for reception will be described.

FIG. 12 is a flowchart showing a data restoration processing routine executed by the facsimile machine 21 for reception. When this routine is started, first, a password is input from the terminal 22 (step 500). If the password matches the code string registered in advance, a method of restoring is selected (step 520). If the printer is specified, the stored data Dm is sequentially read and output to the printer 27 (step 530). If the CRT is specified, the character string Dm is sequentially output to the CRT of the terminal 22. Perform (step 540). Thereafter, it is determined whether or not the character string should be deleted (step 550). If an instruction such as deletion has been issued from the terminal 22, a process of replacing the entire character string Dm with the hexadecimal code $ AA is performed (step 560). Even when the passwords do not match, the character string Dm is similarly replaced in order to maintain the security of the information. Since the character string Dm is not only deleted from the directory but also replaced with the code $ AA, there is no danger that data will be read out once the directory is deleted.

In this embodiment, the image scanner 5 corresponds to a reading unit, the processing of steps 105, 120, and 190 in FIG. 2 corresponds to a run length detecting unit, the processing of step 180 in FIG. 2 corresponds to an encoding unit, The facsimile modem 10 corresponds to the transmitting means, the terminal 2 and the RAM 13 correspond to the combined data setting means, and the processing of steps 125 to 170 in FIG. 2 corresponds to the run length correcting means.

Further, the facsimile modem 30 corresponds to the receiving means,
The processing in step 350 in FIG. 3 corresponds to the run-length extracting means, the processing in step 400 in FIG. 3 and the printer 27 correspond to the image reproducing means, and the processing in steps 370 to 390 in FIG. 530 and 54 in FIG.
The process of 0 corresponds to data output means.

Encoding of data of the present embodiment configured as described above
The decoding method is extremely excellent in that data synthesis / separation can be performed extremely simply and is compatible with the highly versatile Modified Huffman method. Further, there is an excellent advantage that the amount of encoded data does not increase even by combining data. Further, according to the facsimile apparatuses 1 and 21 of the present embodiment, it is possible to easily combine / separate other data with the image data to be transmitted, and furthermore, it is possible to determine that the data has been combined from the restored image. Since it is extremely difficult to visually recognize, there is an advantage that the confidentiality of information is extremely high. In addition, the data transmission efficiency is extremely high such that the amount of information to be transmitted hardly increases or even decreases while the data is being combined. In addition, if the facsimile apparatus on the receiving side has a conventional reception function of the MH method even though data is synthesized, there is an advantage that data can be transmitted and received. Therefore, although data can be synthesized and encrypted, data transmission is not limited to a special device.

While the preferred embodiment of the present invention has been described above, measures against data errors due to transmission errors may be further provided. For example, in a facsimile machine
In G III mode, a scan line synchronization signal is provided at the end of each encoded scan line to limit the damage caused by transmission errors to that scan line only.
EOL is set. This is a code word that is easy to identify, and even if a certain scan line is damaged by transmission errors,
It is used so that subsequent scan lines can be correctly decoded by resynchronization by EOL. In the technique of combining the code of the character string Dm one bit at a time into the run length of other image data as in the above-described embodiment, if an error of one or more bits occurs due to a transmission error, Decoding of the combined information becomes impossible. Therefore, when an error can occur as in the case of transmission via a communication line, it is necessary to devise a method for extracting the first bit of the synthesized character Dm without error. For example, a method is conceivable in which the first bit of each character is always placed immediately after the scanning line synchronization signal EOL. In this case, data that can be combined within the scanning line is wasted, so that the amount of data that can be combined is reduced. The column of “combined amount at the time of error prevention processing” in Table 1 shows the data amount (number of characters) that can be combined in this case, and the “ratio”
Indicates the ratio to the combined amount when no error prevention measures are taken. When this prevention method is adopted, the number of characters that can be combined per scanning line is about three characters on average.
Therefore, even if a transmission error occurs and all information in one scanning line is lost, there is no problem in practical use.

Although the embodiment of the present invention has been described above, the present invention is not limited to such an embodiment. For example, a method of storing data in a magnetic recording device or as a device, or encrypting and transmitting data It goes without saying that the present invention can be implemented in various modes as long as it does not depart from the gist of the present invention.

Effect of the Invention As described in detail above, encoding and encoding of image data of the present invention
According to the decoding method, there is an excellent effect that other data can be very easily combined and separated in encoding / decoding of data using run length.
Moreover, according to the method of the present invention, there is an advantage that other data can be synthesized without increasing the amount of information in the Modified Huffman method that originally compresses image data efficiently. That is, data can be synthesized more efficiently. As a result, the density of data recording / transmission can be further increased. In addition, it is not explicit whether the data is synthesized or not, and the advantage of excellent data confidentiality can be obtained. Further, the encoding / decoding method of the present invention can maintain higher compatibility with the conventional modified Huffman encoding / decoding method.

A facsimile apparatus that directly implements the encoding method of the present invention has an excellent effect that other data can be combined with read image data and transmitted without increasing the information amount of image data to be transmitted. Play. In addition, a facsimile apparatus that directly implements the decoding method of the present invention receives and decodes image data in which other data is combined and encoded, and easily separates other data from the decoded image data. The effect is excellent. Therefore, according to the facsimile apparatus of the present invention, it is possible to easily transmit and receive other data combined with image data with high transmission efficiency, and to realize high confidentiality of data.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a facsimile apparatus for explaining an embodiment of the present invention, FIG. 2 is a flowchart showing a data synthesis / output processing routine in the facsimile apparatus, and FIG. FIG. 4 is an explanatory diagram showing names of pixels on a scanning line to be handled, and FIGS. 5 (A), (B) and (C) are explanatory diagrams showing how data is synthesized when the run length is an even number. 6 (A), 6 (B) and 6 (C) are explanatory diagrams showing a state of data synthesis when the run length is an odd number.
8 and 9 are explanatory diagrams each illustrating a case where data cannot be combined, and FIGS. 10 (A) and (B) and FIG.
FIGS. 12A and 12B are explanatory diagrams showing examples of data combination, and FIG. 12 is a flowchart showing a processing routine for restoring the combined data in the receiving facsimile apparatus. 1,21 ... Facsimile machine 3,23 ... Computer 5,25 ... Image scanner 7,27 ... Printer 10,30 ... Facsimile modem 40 ... Public communication line

Claims (4)

(57) [Claims] 1. A method for sequentially detecting run lengths of pixels on a scanning line from image data obtained by binarizing each pixel of an original image,
In the image data encoding method for encoding the run length and compressing the image data, every time the run length is detected, another binary data to be combined with the image data is read, and the read binary data is read. According to the data, when the binary data is a first value, the run length becomes an even number, and when the binary data is a second value opposite to the first value, the run length is changed. The detected run length is set to 1 so as to be an odd number.
Combining the read binary data with the detected run length by correcting within the number of pixels, and encoding the run length after combining the binary data, encoding the image data. Method. 2. A method for decoding image data, comprising decoding image data encoded by the encoding method according to claim 1, extracting a run length of a pixel, and restoring an image in accordance with the extracted run length. In the above, if the extracted run length is an even number, it is determined that the other binary data that is the first value is combined with the run length, and if the extracted run length is an odd number, Determining that the other binary data, which is the second value, is synthesized with the run length, and separating the other binary data from the image data. . 3. A reading means for binarizing an image written on a document and reading the image, and a run-length detecting means for sequentially detecting run lengths of pixels on a scanning line from the image data read by binarization by the reading means. Means for encoding the run length detected by the run length detecting means to compress the image data; and transmitting the image data compressed by the encoding means to a communication line in a predetermined procedure. Means for preparing the other binary data to be combined with the image data, and setting the combined data every time a run length is detected by the run length detecting means. Means for reading the binary data prepared by the means, and, if the binary data is a first value, according to the read binary data, The detected run length is corrected within one pixel so that the run length is odd when the binary data has a second value opposite to the first value, even if the binary data has a second value. And run length correction means for synthesizing the read binary data with the detected run length, wherein the encoding means executes the run after the binary data is synthesized by the run length correction means. A facsimile apparatus configured to encode a length. 4. A receiving means for receiving image data transmitted from a facsimile apparatus according to claim 3 via a communication line, and decoding the image data received by said receiving means.
A facsimile apparatus comprising: run-length extracting means for extracting a run-length of a pixel; and image reproducing means for reproducing an image in accordance with the run-length extracted by the run-length extracting means. If the run length is even, it is determined that the other binary data that is the first value is combined with the run length. If the extracted run length is odd, the run length is Data separating means for judging that other binary data which is a second value is synthesized, and separating the other binary data from the image data; and binary data separated by the data separating means. A facsimile apparatus comprising: