JP2653497B2 - 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, there is known a modified read (MR) method in which an image is binarized into black and white and the image is compressed using a two-dimensional correlation of the binarized pixels. This method does not perform encoding / compression with only one horizontal scanning line as in the modified Huffman (MH) method in which the run length of a binarized pixel is directly encoded. It uses the vertical correlation with pixels and classifies the change of the boundary of the black and white image between the coded scanning line and the immediately preceding reference scanning line into three types of modes: pass mode, vertical mode, and horizontal mode. Become Since such an image data encoding / decoding method is used in a facsimile machine, in accordance with the facsimile method,
This will be described below.

With respect to the arrangement of pixels, specific pixels are defined as shown in FIG. A specific pixel whose color (white or black) has changed from the previous pixel on the same scanning line is called a changed pixel. That is, a0: a starting point start change pixel on the coded scan line. However, at the start of the coded scan line (left end), a0 is a pixel virtually placed immediately before (left) the first pixel. A1: The first changed pixel on the coded scan line and to the right of a0 a2: The first change pixel on the coded scan line and to the right of a1 b1: The first change pixel on the reference scan line and to the right of a0 and having the opposite color to a0 b2: On the reference scan line and to the right of b1 First change pixel However, if a1, a2, b1, and b2 except a0 cannot be set on the scan line, they are virtually set immediately after (right end) the last (right end) pixel of each scan line. Shall be

Next, three types of modes illustrated in FIG. 13 are defined as follows, and the codewords in Table 1 are applied.

This means that the pass mode b2 is located to the left of a1. At this time, just below b2 is encoded in pass mode, and then Move a0 just below b2. (FIG. 13 (A)) This refers to a case where the distance Δ between the vertical modes a1 and b1 is within ± 3 pixels.
At this time, the position of a1 is encoded in the vertical mode. next,
Move a0 to a1. (FIG. 13 (B)) In other words, in the vertical mode, a pixel position shift in the scanning line direction between the changed pixels on the reference scanning line and the changed pixels on the coded scanning line having the same value (the same color) (see FIG. The position of the changed pixel on the coded scanning line that satisfies the condition that the distance △) is within ± 3 pixels is coded with a code representing the shift.

It is neither horizontal mode nor horizontal mode. At this time, a0a1 and a1a2 are MH
(M (a0a1), M in the rightmost column in the second row of Table 1)
(A1a2)). Next, a0 is moved to the position of a2. (FIG. 13 (C)) In the MR method, the first scanning is performed at least every K scanning lines.
The scanning lines are encoded by the MH method, and the subsequent K-1 scanning lines are encoded according to the above-described mode while referring to the immediately preceding scanning line. This value is called a K parameter. In a facsimile machine, K = K at standard resolution (3.85 lines / mm).
2. K = 4 at high resolution (7.7 lines / mm).

Generally, document images have strong vertical correlation,
When the encoding is performed by the MR method, the ratio of the vertical mode, that is, the deviation of the pixel position in the scanning line direction between the changed pixels on the reference scanning line and the changed pixels on the encoded scanning line in the scanning line direction is ± 3 pixels. Is very high. For example, in CCITT test documents (high resolution), vertical mode averages 89%.

[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. Therefore, conventionally, there has been proposed a method of adopting a scramble encryption method by transposing a scanning line or a pixel to prevent leakage or eavesdropping on a line between facsimile terminals. Since it is restored to a form that can be recognized by anyone, there is no concealment effect for a third party at the receiving terminal, for example, an intermediary such as a document clerk. Even within the same company or group, documents are sent and received on a daily basis that should not be taken carelessly, but no consideration has been given to such issues. That is, in the conventional encoding / decoding method, it can be said that information security is hardly considered.

In addition, a method of encrypting data using a key or the like which is a multi-digit number has also been proposed, but since it is apparent at first glance that the data is encrypted, it is sufficiently considered that the data may be decrypted. It is not a realistic solution. Further, a method of combining the data to be concealed with other data (dummy data) and encrypting the data is also conceivable, but in this case, the data capacity becomes large, and the data to be concealed or the dummy data is not used. However, there is a compatibility problem that decoding cannot be performed by a normal method.

The present invention solves the above problems, and within the framework of a normal MR method,
An 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.

In other words, the present invention according to claim 1 for synthesizing image data by combining other data with the image data, performs encoding scan as an encoding target from image data obtained by binarizing each pixel of an original image. For each of the line and the reference scan line immediately before the encoded scan line, a change image at the beginning of a region where pixels of the same value are continuous on the scan line is extracted, and a change pixel on the reference scan line and the change image In the case of detecting a changed pixel on the coded scanning line that satisfies the condition that the pixel position shift in the scanning line direction between those having the same value with the changed pixel on the coded scanning line is within a predetermined number of pixels, In the method of encoding image data, which compresses the image data by encoding the position of the changed pixel on the detected encoded scan line with a code representing the shift, the change on the encoded scan line satisfying the condition Pixel Each time the binary data is read out, the other binary data to be combined with the pixel data is read out, and according to the read binary data, if the binary data is a first value, the shift is equal to the predetermined number of pixels. Within a minute and the even number, and when the binary data is a second value opposite to the first value, the detected change pixel so that the shift is within the predetermined number of pixels and an odd number. Is moved within one pixel on the coded scanning line, thereby combining the read binary data with the displacement of the pixel position, and using a code representing the displacement after combining the binary data, Encoding the position of the changed pixel on the encoded scanning line detected above.

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. A code representing the shift is sequentially extracted from the converted image data, and the extracted code is decoded to restore the arrangement of pixels on each scanning line, thereby recovering an image. For each of the two adjacent scanning lines after restoring the arrangement of the above, the changed pixel at the head of the area where pixels of the same value are continuous on the scanning line is extracted, and the changed pixel on one scanning line and the other If the shift of the pixel position in the scan line direction between pixels having the same value with the change pixel on the scan line is within the predetermined number of pixels and even, the first shift is regarded as the shift.
Judge that other binary data which is the value of
If the shift of the pixel position is within the predetermined number of pixels and is an odd number, it is determined that another binary data that is the second value is combined with the shift, and the The gist of the present invention is a method of decoding image data, which is characterized by separating other binary 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. From the obtained image data, for each of the encoded scan line to be encoded and the reference scan line immediately before the encoded scan line, the change at the head of the area where pixels of the same value are continuous on the scan line A pixel is extracted, and a condition is satisfied that a shift of a pixel position in a scanning line direction between pixels having the same value between a changed pixel on the reference scanning line and a changed pixel on the encoded scanning line is within a predetermined number of pixels. Encoding means for compressing the image data by encoding a position of the changed pixel on the detected coded scanning line with a code representing the shift when detecting a changed pixel on the coded scanning line; The sign Transmitting means for outputting the image data compressed by the converting means to the communication line in a predetermined procedure, and a facsimile apparatus comprising: a synthetic data setting means for preparing other binary data to be synthesized with the image data; Each time a changed pixel on the encoded scan line that satisfies the condition is detected by the encoding unit, the binary data prepared by the composite data setting unit is read, and the binary data is read according to the read binary data. When the binary data is the first value, the shift is within the predetermined number of pixels and is even, and when the binary data is the second value opposite to the first value, the shift is By moving the changed pixel detected by the encoding means within one pixel on the encoded scanning line so as to be an odd number within the predetermined number of pixels, the position of the pixel is shifted. Synthesizing means for synthesizing the read binary data, wherein the encoding means uses a code representing the shift after the binary data is synthesized by the synthesizing means, on the detected encoded scan line. And coding the position of the changed pixel of.

A facsimile apparatus according to claim 4, which directly implements the decoding 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. Restoring means for sequentially extracting codes representing the shift from the image data received by the receiving means, decoding the extracted codes and restoring the arrangement of pixels on each scanning line, Image reproducing means for reproducing an image in accordance with the arrangement of the pixels, and for each of two adjacent scanning lines in which the arrangement of pixels has been restored by the restoration means, a pixel having the same value on the scanning line The changed pixel at the head of the continuous area is extracted, and the changed pixel on one scanning line and the changed pixel on the other scanning line are scanned in the scanning line direction between those having the same value. If the deviation of the pixel position is within the predetermined number of pixels and is even, it is determined that another binary data that is the first value is combined with the deviation, and the deviation of the pixel position is determined. If the number is within the predetermined number of pixels and is an odd number, it is determined that the other binary data that is the second value is combined with the shift, and the other binary data is converted from the image data. And a data output means for outputting the binary data separated by the data separation 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:
For each of the encoded scan line to be encoded and the reference scan line immediately before the encoded scan line, extract a changed pixel at the beginning of a region where pixels of the same value are continuous on the scan line,
A changed pixel on an encoded scan line that satisfies the condition that the pixel position shift in the scan line direction between the changed pixel on the reference scan line and the changed pixel on the encoded scan line in the scan line direction is within a predetermined number of pixels. Is detected, the image data is compressed by encoding the detected position of the changed pixel on the encoded scan line with the code representing the shift.

That is, the image data is compressed by a procedure such as the above-described vertical mode of the modified read (MR) method, and is further combined with the image data every time a changed pixel on the coded scanning line satisfying the above condition is detected. The other binary data to be read is read, and the binary data is combined with the image data by the following procedure.

That is, in accordance with the read binary data, when the binary data is the first value, the shift is within the predetermined number of pixels and is even, and the read binary data is the first value. By moving the detected changed pixel within one pixel on the coded scanning line so that the deviation is within the predetermined number of pixels and becomes an odd number when the second value is opposite to the second value, The read binary data is combined with the displacement of the pixel position. In this way, by encoding the position of the changed pixel on the detected encoded scanning line with the code representing the shift after the combination of the binary data, the original image data is encoded and compressed. Is combined with other binary data.

Next, 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 decoding method according to claim 2, claim 1
Since the code representing the shift is sequentially extracted from the image data encoded by the encoding method described in the above, and the extracted code is decoded to restore the arrangement of the images on each scanning line, the image is restored. However, a changed pixel is extracted for each of two adjacent scanning lines after the pixel arrangement is restored, and a changed pixel having the same value between a changed pixel on one scanning line and a changed pixel on the other scanning line is extracted. If the displacement of the pixel position in the scanning line direction is within the predetermined number of pixels and is even, it is determined that another binary data that is the first value is combined with the displacement, and the displacement of the pixel position is determined. If the shift is within the predetermined number of pixels and is an odd number, it is determined that another binary data, which is the second value, is combined with the shift, and the other binary data is separated from the image data. You do it.

On the other hand, in the facsimile apparatus according to claim 3, which directly implements the encoding method according to claim 1, the reading means binarizes and reads the image written on the original, and the encoding means reads the image. From the image data read by binarization, a changed pixel is extracted for each of an encoded scan line to be encoded and a reference scan line immediately before the encoded scan line, and a changed pixel on the reference scan line is extracted. When a changed pixel on the coded scanning line that satisfies the condition that the pixel position shift in the scanning line direction between those having the same value as the changed pixel on the coded scanning line is within a predetermined number of pixels, Image data is compressed by encoding the detected position of the changed pixel on the encoded scan line with a code representing the shift. Then, the transmitting means outputs the image data compressed by the encoding means to the communication line in a predetermined procedure.

In this case, 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 combining means performs the encoding scan satisfying the condition by the encoding means. Each time a changed pixel on the line is detected, the binary data prepared by the combined data setting means is read out. If the binary data is the first value according to the read binary data, the shift is performed. Is an even number within the predetermined number of pixels, and the binary data is
The changed pixel detected by the signing means within one pixel on the coded scanning line so that the deviation is within the predetermined number of pixels and an odd number when the value is a second value opposite to the value of And the read binary data is combined with the displacement of the pixel position. Then, the encoding unit encodes the position of the changed pixel on the detected encoded scanning line by using a code representing a shift after the binary data is combined by the combining unit.

In other words, in the facsimile apparatus according to the third aspect, when the synthesizing means and the encoding means function as described above, other binary data is synthesized when the image data is encoded and compressed.

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. Receiving and restoring means,
Codes representing the shifts are sequentially extracted from the image data received by the receiving means, and the extracted codes are decoded to restore the arrangement of pixels on each scanning line. Then, the image reproducing means reproduces the image in accordance with the arrangement of the pixels restored by the restoring means.

In this case, in particular, in the facsimile apparatus according to claim 4, the data separating unit extracts a change pixel for each of two adjacent scanning lines whose pixel arrangement has been restored by the restoration unit, and changes the change pixel on one of the scan lines. If the shift of the pixel position in the scan line direction between pixels having the same value between the pixel and the change pixel on the other scan line is within the predetermined number of pixels and even, the shift is the first value. It is determined that other binary data has been synthesized, and if the shift of the pixel position is within the predetermined number of pixels and is an odd number, the shift is regarded as the second shift.
It is determined that other binary data having the value of (i) has been synthesized, and the other binary data is separated 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 separated from the image data. It is.

[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 described here as the transmitting side will be mainly described.

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 machines 1, 21 are connected to a public communication line 40 via built-in facsimile modems 10, 30.

Next, data combining / outputting processing and data receiving / separating processing in both facsimile apparatuses 1 and 21 will be sequentially 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 details of data combining processing in the processing routine. In the following description, a0, a1, a2, b
As shown in FIG. 12 and described in the section of [Prior Art], 1 and b2 denote the pixels (change pixels) at the positions where the arrangement of the white or black image in the encoding scan line and the reference scan line is inverted. Shall be shown.

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 in the form of a character string from the terminal 2 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, a process of setting a variable Kx for reference of the K parameter in the MR method to an initial value 1 is performed (step 100), and whether the resolution of the image data reading is the standard mode or the high-resolution mode is determined. Is determined (step 110). In the case of the resolution mode, the K parameter is set to the value 4 (step 113), and in the case of the standard mode, the K parameter is set to the value 2 (step 113).
116). Thereafter, it is determined whether or not the variable Kx has the value 1 (step 120).

If it is determined that the variable Kx = 1, that is, the scanning line to be encoded in the MH system as at the beginning of the page, an end-of-line (EOL) +1 signal is output as the head of the line (step 1).
25) Until the end of one line, a process of encoding and outputting the pixel arrangement in the MH system is performed (steps 130 and 135).

On the other hand, if the variable Kx is a value other than the value 1 (step 12
0), assuming that the line is to be encoded by the MR method,
OL + 0 is output (step 140), and processing for setting a0 to the further left of the first pixel is performed (step 145). next,
As described in the section of [Prior Art], a process for detecting pixels (referred to as changed pixels) a1, a2, b1, b2 in which continuous white or black pixels change on an encoding scan line and a reference scan line is performed. Perform (step 150). For the definition of each pixel,
See FIG.

With respect to the pixels thus detected, it is determined whether or not the pixel b2 is on the left side of the pixel a1 (step 150). If the pixel is on the left side, the pixel corresponds to the pass mode.
This is output via the facsimile modem 10, and the pixel a0 is moved to a position immediately below the pixel b2 in preparation for the next encoding.
A setting process is performed (step 160). An example of the arrangement of pixels corresponding to the pass mode and the movement of the pixel a0 are as shown in FIG. 13 (A).

On the other hand, if the pixel b2 is not to the left of the pixel a1 (step 155), the distance Δ (a1b1) between the pixel a1 and the pixel b1 is 3
It is determined whether it is within the range (step 165). If the distance is 3 or more, it corresponds to the horizontal mode as illustrated in FIG. 13 (C), so that it is coded in the horizontal mode, and this is output via the facsimile modem 10 and the next code is output. The pixel a0 is moved / set to the position of the pixel a2 in preparation for the conversion process (step 170).

If the distance Δ (a1b1) between the two pixels a1 and b1 is within the value 3, it corresponds to the vertical mode as exemplified in FIG. 13 (B). Is determined, and the data Dm (i) is synthesized if possible (step 180). The determination of whether or not data combination is possible and details of the combination will be described later with reference to FIG.
After combining the data in the vertical mode in this manner, a process of encoding the data in the vertical mode and outputting it is performed, and a process of moving and setting the pixel a0 to the position of the pixel a1 in preparation for the next encoding is performed ( Step 190).

Pass mode (step 160), horizontal mode (step 1)
70), after performing encoding / output in each of the vertical modes (step 190), it is determined whether or not encoding of one line has been completed (step 195). One line must be completed. For example, the process returns to step 150 described above, and the process is repeated from the process of newly detecting the pixels a1, a2, b1, and b2 based on the pixel a0 set after the encoding. On the other hand, when the encoding is completed up to the end of the encoded scanning line (step 195), the variable Kx for determining the K parameter of the scanning line is incremented by 1 (step 200), and this variable Kx It is determined whether or not it has become larger (step
205) If the value is larger than the K parameter, a process for returning to the initial value 1 is performed (step 210).

Thereafter, it is determined whether or not one page has been completed (step 215). If not, the process is repeated from the determination on the variable Kx (step 120). That is, the process is repeated from the determination of whether the next line is a line to be encoded by the MH method or a line to be encoded by the MR method. If it is determined that the transmission of the image for one page has been completed, a code RTC indicating the end of the page is output (step 220), and "NEXT"
And the process proceeds to a phase D process. 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.

The processing of the phase C has been briefly described above. Next, the details of the data synthesis will be described. In step 180 shown in FIG. 2, first, it is determined what condition the gap Δ (a1b1) from the pixel a1 on the coded scanning line to the pixel b1 on the reference scanning line is in (step 25).
0). It should be noted that only Δ (a1b1) is simply indicated as Δ in the following description. In the case of the vertical mode, the distance between both pixels is within ± 3. Therefore, paying attention to the evenness, Δ = 0,2, Δ = 1,3, Δ = -1, -3 In the case where Δ = −2, the case is divided into: In each case, there are certain restrictions between pixels in order to combine data. This is due to the fact that data may not be able to be restored by combining 1-bit data depending on the arrangement of pixels. Therefore, in each case, it is determined whether or not the condition is satisfied.

In the case of Δ = 0 or 2, the distance Δ (a0a1) between the pixel a0 and the pixel a1 is equal to or more than 3 (step 260), and the pixel b0, which is the change pixel immediately before the pixel b1 on the reference scanning line, Distance Δ from pixel a1 (b0a1)
Only when the value is 2 or more (step 262), data synthesis is performed. If these conditions are satisfied, the character string Dm to be synthesized is sequentially read out and its i-th bit (hereinafter, this is referred to as bit Dm (i))
It is determined whether or not is the value 1 (step 266),
If the value is 1, a process of moving the pixel a1 on the encoded scanning line to the left by one pixel is performed (step 268). If the condition is not satisfied (steps 260 and 262) and if the bit Dm (i) is not the value 1, no processing is performed. As a result, as shown in FIGS. 4 (A1) and (A2), when Δ = 0,2, if the bit Dm (i) is inserted, when the bit Dm (i) has the value 1, the gap Δ becomes Oddly, bit Dm (i) has value 0
In this case, the gap Δ is set to an even number.

In the case of Δ = 1,3 In this case, as a condition for synthesis, the distance Δ (a0a1) between the pixel a0 and the pixel a1 is equal to or more than 2 (step 27).
0) and the distance Δ (b0a1) between the pixel b0 and the pixel a1 is a value of 1.
(Step 272), and the distance Δ (b1a2) between the pixel b1 and the pixel a2 is equal to or greater than 1 (step 27).
4) is determined. If these conditions are satisfied, it is determined whether or not the bit Dm (i) to be synthesized has a value of 0 (step 276). If the value is 0, the pixel on the coded scanning line is determined. A process is performed to move a1 one pixel to the right (step 278). If the condition is not satisfied (steps 270, 272, 274) and if the bit Dm (i) is not the value 0, no processing is performed. As a result, FIG.
As shown in 1) and (B2), when Δ = 1,3, the bit Dm
When (i) is inserted, the gap Δ is set to an odd number when the bit Dm (i) has a value of 1, and the gap Δ is set to an even number when the bit Dm (i) has a value of 0.

In the case of Δ = −1, −3 In this case, as a synthesis condition, the distance Δ (a0a1) between the pixel a0 and the pixel a1 is 4 or more (step 28).
0) and the distance Δ (b0a1) between the pixel b0 and the pixel a1 is a value of 3.
(Step 282), and the distance Δ (a1b2) between the pixel a1 and the pixel b2 is equal to or more than 1 (step 28).
4) is determined. If these conditions are satisfied, it is determined whether or not the bit Dm (i) to be synthesized has a value of 0 (step 286). A process is performed to move a1 one pixel to the left (step 288). If the condition is not satisfied (steps 280, 282, 284) and if the bit Dm (i) is not 0, no processing is performed. As a result, FIG.
As shown in (1) and (C2), when the bit Dm (i) is inserted when Δ = −1, −3, when the bit Dm (i) has the value 1, the gap Δ is odd and the bit Dm (i) is When (i) has the value 0, the gap Δ is set to an even number.

When Δ = −2 When the distance Δ (a1a2) between the pixel a1 and the pixel a2 is greater than or equal to 2 (step 290) and when the distance Δ (a1b2) between the pixel a1 and the pixel b2 is greater than or equal to 2 (step 292). Only for data synthesis. If these conditions are satisfied, it is determined whether or not the bit Dm (i) to be synthesized has the value 1 (step 296). If the value is 1, the pixel a1 on the coded scanning line is determined. Is moved to the right by pixels (step 298). If the condition is not satisfied (steps 290 and 292) and if the bit Dm (i) is not the value 1, no processing is performed. As a result, FIG. 4 (D1),
As shown in (D2), when Δ = −2, the bit Dm (i)
Is inserted, when the bit Dm (i) has a value of 1, the gap Δ is odd, and when the bit Dm (i) has a value of 0, the gap Δ
Is set to an even number.

In the processing described above, the condition of the distance between pixels when combining data is that, as described above, if the position of pixel a1 is shifted by one bit in accordance with the value of bit Dm (i), the original This is because the arrangement of the pixels in the image itself may be changed, or the previous mode may be destroyed. For example, as shown in FIG. 5 (A), the gap Δ (a0a1) <
When bit Dm (i) = 1 is synthesized at the time of 2, pixels are continuous, so that decoding is not possible as shown in FIG. Even conceivable. Further, as shown in FIG. 6A, the distance Δ (b0a1) between the pixel b0 and the pixel a1 is a value of 2
In the case of less than 1, if the bit "1" is combined, as shown in FIG. 6 (B) at the time of decoding, the combining condition Δ (b0a1) ≧ 1 when Δ = 1,3 is not satisfied, and the data becomes It is determined that they have not been combined, and the bit “1” cannot be decoded. Therefore, a condition of Δ (b0a1) ≧ 2 is required.
Further, as shown in FIG. 7 (A), the gap Δ (a0a1) <
In the case of 3, combining bits "1" gives the seventh
As shown in FIG. (B), the gap Δ
= −2, whether the data could not be synthesized because Δ (a1a2) ≧ 2 was not satisfied, or whether the bit “0” was synthesized as shown in FIG. 7 (C) I can no longer do it. Therefore, considering the above condition of Δ (a0a1) ≧ 2, Δ (a0a1) ≧ 3 and Δ (b0a1) ≧
2 is the data synthesizable condition when Δ = 0,2.

The same applies to other cases, and the conditions shown in the flowchart of FIG. 3 are summarized as follows.

(1) When Δ = 0,2, Δ (a0a1) ≧ 3 and Δ (b0a1) ≧ 2 (2) When Δ = 1,3 Δ (a0a1) ≧ 2 and Δ (b0a1) ≧ 1 and Δ ( b1a2) ≧ 1 (3) When Δ = −1, −3, Δ (a0a1) ≧ 4 and Δ (b0a1) ≧ 3 and Δ (a1b2) ≧ 1 (4) When Δ = −2, Δ (a1a2 ) ≧ 2 and Δ (a1b2) ≧ 2 If the composition is performed in consideration of these constraints at the time of MR encoding, the arrangement of pixels may be completely changed or confusion as to whether or not data is combined may be caused. Therefore, it is possible to correctly extract the composite data sequence at the time of decoding.

Next, the processing of the facsimile machine 21 that receives the image data generated and output by executing the above-described data synthesis processing will be described. FIG. 8 is a flowchart showing a data reception / separation processing routine executed by the facsimile machine 21 for reception.

The facsimile apparatus 21 for reception sets the call setup phase A
When the connection is made to the facsimile machine 1 on the transmission side via the communication line 40 via the communication line 40, the phase B prior to transmission / reception of the message is completed, and thereafter, the phase shifts to the phase C for receiving the message. In phase C, as shown in FIG. 8, first, a process of inputting the first code received via the facsimile modem 30 is performed (step 300), and a process of determining the received signal is performed (step 31).
0). If the received code is determined by the K parameter to be EOL + 1 indicating a line coded by the MH system, the code is further input (step 32).
0), the input code (run length) is decoded according to the MH method (step 330). Since the decoded data does not include the composite data, the data is output to the printer 27 as it is (step 340). The input of the code, the code of the data, and the output are repeated until the processing of one line is completed (step 350). When the processing for one line is completed, the process returns to step 300, and the processing is repeated from the input of the code at the head of the line.

On the other hand, if the leading code of the line is EOL + 0, it is determined that the line has been encoded by the MR method and that data has been synthesized (step 310). Performs separation / output processing. First,
The code is input (step 400), and the mode is determined according to the code shown in Table 1 (step 410). According to the mode of the input code, decoding in the horizontal mode (step 420), decoding in the pass mode (step 430), and decoding in the vertical mode (step 440) are performed.

When decoding according to the vertical mode, next, regarding the relationship between the arrangement on the immediately preceding reference scanning line and the arrangement of pixels on the decoded scanning line, whether or not a condition for separating data superimposed on this is satisfied. (Step 45
0). These conditions correspond to the conditions (steps 260, 262, 270 to 274, 280 to 284, 290, 292 in FIG. 3) at the time of combining described for the facsimile machine 1 for transmission.

If such a condition is satisfied, it is determined that data has been synthesized, and data separation processing is performed. That is, it is determined whether or not the distance Δ (a1b1) between the pixel b1 and the pixel a1 on the immediately preceding reference scanning line is an even number (step 46).
0), in the case of an even number, it is determined that bit 0 has been synthesized, and the value 0 is set in bit Dm (i) (step 470);
If it is odd, the value 1 is set to the bit Dm (i) (step 475). Thereafter, assuming that one bit of data is separated, a variable i indicating the number of bits is set to a value of 0 to 7
Is incremented by 1 within the range (step 48)
0). Note that the variable m is incremented each time 8 bits are separated, and a new character Dm is decoded. This variable m
Is not performed in the routine shown in FIG. 8 because the synthesized character string Dm may cover a plurality of pages of image data.

After the image data is separated in this way, or when the image data is decoded in the horizontal mode, pass mode, or decoded in the vertical mode but the separation condition is not satisfied, the image data is output to the printer 27 in accordance with the decoded data. An image is printed (step 485). The processing described above
Repeat until the line ends (step 490). When the processing of one line is completed, the processing is repeated from the input of the leading code of the line.

If the head code of the line is the code RTC indicating the end of the page (step 310), a page break is output to the printer 27, and the process exits from "NEXT" and shifts to the processing of phase D. 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. 8 again.

By the above processing, the receiving facsimile machine 21 that has received the data transmission prints the image on the document 51 by the printer 27. FIG. 9 (A) shows the high resolution mode (7.7 lines /
9 (B) is an explanatory view showing a part of a received image when only the image of the original 51 is transmitted in the original 51 mm, and FIG. FIG. 3 is an explanatory diagram showing a part of an image. 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. Since the facsimile image standardizes one scanning line of the A4 size to 1728 dots (8.23 dots / mm), one dot in the horizontal direction is about 0.12 mm. As described above, since the facsimile image has a high resolution, even if one dot on the scanning line is increased or decreased, it hardly affects the human eyes. Also, as shown in FIG. 9 (B),
There is no possibility that the data is synthesized with this image, and the confidentiality of the data is extremely high.

FIGS. 10A and 10B are explanatory diagrams showing an example of data synthesis using other images. Table 2 shows the amount of data that can be combined and the amount of transmission of encoded data in these transmission experiments. Documents 2 and 4 shown in Table 2 are partially shown in FIGS. 9 and 10. Also, since the manuscripts 4 and 7 are manuscripts having a large number of characters and the appearance probability of the vertical mode is high, it can be understood that the amount of data that can be synthesized is considerably larger than that of a photograph or a picture. From these results, when an A4-size original (1728 x 2375 pixels) is transmitted by facsimile, thousands of characters are used in the examples shown in Figs. 9 and 10. It can be understood that data of tens of thousands of characters can be synthesized in many cases. In addition, the amount of information to be transmitted by the combination of such data hardly increases, and sometimes decreases. However, the code amount in Table 2 is in byte units, and includes the EOL and RTC signals, but does not include the FILL bit. The ratio indicates the ratio of the code amount of the information composite image to the code amount of the original image. In addition, since the vertical mode averages 89% in the CCITT test document (high resolution), this method of synthesizing data using the vertical mode is extremely efficient.

Next, a process for extracting the data Dm extracted by the process shown in FIG. 8 and stored in the built-in RAM of the facsimile machine 21 for reception will be described. FIG. 11 is a flowchart showing a data restoration processing routine executed by the receiving facsimile machine 21. When this routine starts,
First, a password is input from the terminal 22 (step 50
0), if the password matches the code string registered in advance,
Further, a method of restoration is selected (step 520).
If a printer is designated, the stored data Dm is sequentially read out and output to the printer 27 (step 530), and the CRT
If is designated, a process of sequentially outputting the character string Dm to the CRT of the terminal 22 is performed (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, all the character strings Dm are deleted.
Perform the process of replacing with base code $ AA (step 56
0). 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 the reading means, the processing of steps 145 to 155, 165, and 190 in FIG. 2 corresponds to the encoding means, the facsimile modem 10 corresponds to the transmitting means, and the terminal 2 and the RAM 13 Corresponds to the combined data setting means, and the processing of FIG. 3 executed in step 180 of FIG. 2 corresponds to the combining means.

Further, the facsimile modem 30 corresponds to the receiving means,
The processing of steps 410 and 440 in FIG. 8 corresponds to the restoration means,
The processing in step 485 in FIG. 8 and the printer 27 correspond to image reproducing means, the processing in steps 450 to 480 in FIG. 8 corresponds to data separation means, and the processing in steps 530 and 540 in FIG. 11 correspond to data output means. Is equivalent.

Encoding of data of the present embodiment configured as described above
The decoding method is extremely excellent in that the data can be synthesized and separated in a very simple manner and is compatible with the highly versatile modified read method. Also,
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. Further, if the receiving-side facsimile apparatus has a reception function of the conventional MR system 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
A scan line synchronization signal at the end of each coded scan line to limit the damage caused by transmission errors in G III mode to only that scan line
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. Therefore, when this prevention method is adopted, the number of characters that can be combined per scanning line is about three characters on average, but the reliability of the separated data increases accordingly. Also, since the data synthesized per scanning line is equivalent to 3,4 characters, 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 for recording data on a magnetic recording device or as an apparatus, 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 and decoding of data using the correlation with the arrangement of pixels on the reference scanning line. In particular, 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 a modified read vertical mode in which image data is originally efficiently compressed. That is, data can be efficiently synthesized. 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 encoding / decoding method of the conventional modified read system.

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. Further, a facsimile apparatus which directly implements the encoding method of the present invention receives and encodes image data in which other data is synthesized 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.

In addition, the feature of this method that the amount of transmission code is not increased by combining information is that when applied to communications such as facsimile, a large amount of information can be transmitted in the same transmission time in the current line system, which is an advantage of cost reduction. Bring. Therefore, this means that data compression has been achieved without changing the existing coding system, which also leads to effective use of line resources. As information to be combined, not only a document but also other information (for example, an image or a program) can be used, so that the use form of the information medium in facsimile communication is expanded.

[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. Flow chart showing details, FIG. 4 (A1), (A2), (B1), (B
2), (C1), (C2), (D1), and (D2) are explanatory diagrams each showing a state of data synthesis, and FIGS. 5 (A), (B), 6 (A), and (B). 7 (A), 7 (B), and 7 (C) are explanatory diagrams each illustrating a case where data cannot be combined, FIG. 8 is a flowchart showing a data separation / decoding processing routine, and FIG. 9 (A). , (B) and FIGS. 10 (A), (B) are explanatory diagrams showing examples of data synthesis, respectively.
FIG. 11 is a flowchart showing a processing routine for restoring the combined data in the receiving facsimile machine,
FIG. 12 is an explanatory diagram showing names of pixels on a scanning line to be handled, and FIG. 13 is an explanatory diagram showing a state of encoding of each mode in the MR system. 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. An image processing method comprising the steps of: converting image data obtained by binarizing each pixel of an original image into an encoding scan line to be encoded and a reference scan line immediately before the encoding scan line; The change pixel at the head of the area where the pixels of the value are continuous is extracted, and the change pixel on the reference scan line and the change pixel on the coded scan line have the same pixel value in the scan line direction between those having the same value. When a changed pixel on the coded scanning line that satisfies the condition that the shift is within a predetermined number of pixels is detected, the position of the detected changed pixel on the coded scanning line is encoded with a code representing the shift. In the image data encoding method of compressing the image data, every time a changed pixel on the encoded scan line that satisfies the condition is detected, another binary data to be combined with the image data is read out, The reading According to the extracted binary data, when the binary data is the first value, the shift is within the predetermined number of pixels and even, and the binary data is the first value.
The detected changed pixel is moved within one pixel on the coded scan line so that the shift is within the predetermined number of pixels and is odd when the second value is opposite to the second value. By combining the read binary data with the displacement of the pixel position, the position of the detected changed pixel on the encoded scan line is encoded by a code representing the displacement after the combination of the binary data. A method of encoding image data. 2. The method according to claim 1, wherein codes representing the shifts are sequentially extracted from the image data encoded by the encoding method, and the extracted codes are decoded to restore the arrangement of pixels on each scanning line. Accordingly, in the image data decoding method for restoring an image, in each of two adjacent scanning lines after restoring the arrangement of the pixels, a pixel having the same value on the scanning line is located at the head of a continuous area. The change pixel is extracted, and the shift of the pixel position in the scan line direction between those having the same value between the change pixel on one scan line and the change pixel on the other scan line is within the predetermined number of pixels and is an even number. If so, it is determined that the other binary data that is the first value is combined with the shift, and if the shift of the pixel position is within the predetermined number of pixels and is odd, the shift is determined to be the shift. Another binary data which is the second value Determining that the data has been combined, and separating the other binary data from the image data. 3. A reading means for reading an image written on a document in a binarized form, an encoding scan line to be encoded and an encoding scan from the image data read in a binary form by the reading means. For each of the reference scan lines immediately before the line, the change pixel at the head of the area where pixels of the same value are continuous on the scan line is extracted, and the change pixel on the reference scan line and the change pixel on the encoded scan line are extracted. When a change pixel on the coded scanning line that satisfies the condition that the pixel position in the scanning line direction between pixels having the same value in the scanning line direction is within a predetermined number of pixels is detected, the detected coded scan is performed. The position of the change pixel on the line is
A facsimile comprising: an encoding unit that compresses the image data by encoding with the code representing the shift; and a transmission unit that outputs the image data compressed by the encoding unit to a communication line in a predetermined procedure. In the apparatus, a combined data setting unit that prepares another binary data to be combined with the image data, and each time a changed pixel on the encoded scanning line that satisfies the condition is detected by the encoding unit, the combined data is combined. Reading the binary data prepared by the data setting means, and according to the read binary data, when the binary data is the first value, the shift is within the predetermined number of pixels and is even; When the binary data is a second value opposite to the first value, the shift detected by the encoding means is set so that the shift is within the predetermined number of pixels and an odd number. And a synthesizing unit for synthesizing the read binary data with the shift of the pixel position by moving the coded pixel within one pixel on the coded scanning line. Encoding the position of the changed pixel on the detected coded scan line with a code representing the shift after the binary data is synthesized by the facsimile apparatus. 4. A receiving means for receiving image data transmitted from a facsimile apparatus according to claim 3 via a communication line, and sequentially extracting a code representing said shift from the image data received by said receiving means. A facsimile apparatus including: a decoding unit that decodes the extracted code to restore the arrangement of pixels on each scanning line; and an image reproduction unit that reproduces an image in accordance with the arrangement of pixels restored by the restoration unit. The adjacent two pixels whose pixel arrangement has been restored by the restoration means
For each of the two scanning lines, extract the changed pixel at the beginning of the area where pixels of the same value are continuous on the scanning line, and extract the same value of the changed pixel on one scanning line and the changed pixel on the other scanning line. If the deviation of the pixel position in the scanning line direction between them is within the predetermined number of pixels and is even, it is determined that the other binary data as the first value is combined with the deviation. If the displacement of the pixel position is within the predetermined number of pixels and is an odd number, it is determined that another binary data that is the second value is combined with the displacement, and from the image data, A facsimile apparatus comprising: a data separation unit that separates the other binary data; and a data output unit that outputs the binary data separated by the data separation unit.