JP2817448B2 - Encoding / decoding device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image communication terminal, and more particularly to a communication terminal for transmitting and receiving image data such as a facsimile.

[0002]

2. Description of the Related Art Image communication using facsimile includes immediate transmission and reception and storage transmission and reception. These communications are described in Electronics Technology, vol. 32, no. On pages 11, 22 to 29, there is a description entitled "Technology for Making Facsimile Highly Functional and Multifunctional and Using Memory" (August 1990).

In the immediate transmission / reception, image data input from a scanner or the like is immediately encoded and transmitted to a partner terminal.
Alternatively, no code data other than for the purpose of time alignment of signal processing is stored in the facsimile so that the code data sent from the partner terminal is immediately decoded and recorded by the printer.

On the other hand, in storing and transmitting, by providing a means for storing coded data of one or more screens, processing such as image data input from a scanner, transmission and reception with a partner terminal, and image data output to a printer can be performed in a timely manner. Can be shifted.
For this reason, (1) when transmitting the same image to a plurality of partners, the accumulated code data may be repeatedly transmitted to the plurality of partners.

(2) When the partner terminal is busy, the stored code data may be transmitted to the partner at a later time.

(3) Signal processing for image input from a scanner or image output to a printer can be set independently of signal processing for transmission and reception with a partner terminal.

The principle of arithmetic coding is described in, for example, IEICE Journal, Vol. 71, No. 7, pages 669 to 675 (July 1988), which is described in a document entitled "Still image coding and its application". If the occurrence probabilities of two symbols 0 and 1 are P0 and P1 and the number of 0s in the N symbol sequences is N0 and the number of 1s is N1, the N symbol sequences are represented by arithmetic codes. The number of bits required for (1) is-(N0 * Log (P0) + N1 * Log (P1)). Here, the base of Log is 2, and N = N0 + N
It is one.

The worst value of the compression ratio by the arithmetic code is that both occurrence probabilities P0 and P1 of both symbols in the above equation are １ ／.
Therefore,-(N0 * Log (1/2) + N1 * Log (1/2)) = N0 + N1. That is, in the principle of the arithmetic code, the capacity of the code data does not exceed that of any input data. This is traditionally used,
This is a feature that cannot be achieved by the MH, MR, and MMR coding methods. For example, a dither image is a method of creating a pseudo halftone image by dispersion of white and black pixels, but the occurrence probability of both symbols does not reflect the properties of the input image. Therefore, in MH, MR, and MMR coding for a dither image, the capacity of code data may exceed the capacity of input data.

In the implementation of the arithmetic coding system, the compression rate on the above principle may be deteriorated due to factors such as restrictions on the numerical accuracy of the arithmetic unit and addition of control data.
The maximum capacity required to store one screen of code data can be set in advance with a certain degree of accuracy.

Although many coding schemes based on the principle of arithmetic coding have been proposed, it is needless to say that the names of the coding schemes are not limited since the same effects as described above can be obtained. .

[0011]

As described above, the storage transmission / reception can realize various functions. However, storage means for encoding and storing image data input from a scanner or the like is required. However, there is a problem that the number of screens that can be stored in the storage unit is not known in advance because the capacity of one-screen code data greatly changes depending on the image characteristics.

Further, since the capacity of the code data is not constant, the time required for data transfer of one screen cannot be set in advance. This means that, for example, when the stored code data is recorded by a printer, the time required for signal processing inside a facsimile such as a storage unit, a decoding unit, or a printer cannot be set in advance. This is an issue in determining the configuration specifications.

[0013]

In order to solve the above-mentioned problems in an image communication terminal, the present invention provides means for arithmetically coding image data, means for storing arithmetic code data, and decoding the stored arithmetic code data. An encoding / decoding device is constituted by means, means for performing encoding corresponding to the capability of the partner terminal, and means for decoding code data sent from the partner terminal.

[0014]

The image data from the input means is converted into code data by the first coding means using arithmetic codes, and the maximum capacity of code data corresponding to the image data of one screen is determined by the size of one screen to be coded. The capacity of image data. Therefore,
The free storage capacity required for storing arithmetic code data in the storage means or the data transfer speed can be set prior to the encoding process. On the other hand, the coding means such as MH, MR, and MMR cannot set the maximum capacity of the code data corresponding to the image data of one screen prior to the coding processing, so that the above function cannot be realized. The same applies to the recording of image data by a recording device such as a printer. By providing a first decoding device using arithmetic codes, the data transfer speed or the buffer memory capacity is set prior to the decoding process.

In communication with a partner terminal via a network, it is necessary to transmit mutually compatible code data after confirming the decoding procedure of the partner terminal in advance. According to the present invention, the code data stored in the storage means is decoded, and encoded by the second encoding means into code data compatible with the partner terminal and transmitted. The same applies to reception. The image data decoded by the second decoding unit is converted into coded data by the first coding unit and stored in the storage unit.

By converting the image data input and accumulated by the scanner or the like into a multi-valued image, if the decoding procedure of the partner terminal is a binary image encoding process, data conversion from the multi-valued image to the binary image is performed. Is performed, and if the decoding procedure of the partner terminal is an encoding process of a multi-valued image, the second encoding process is executed without changing the multi-valued image, so that various partner terminals can be handled. Further, when performing editing processing using the image data stored in the storage unit, the editing processing is performed on the image data decoded by the first decoding unit, and the result is again returned to the first encoding unit. By converting the image data into code data and accumulating it, for example, new image data combining a plurality of image data is created.

In the above signal processing, the signal processing speed of the arithmetic coding and decoding means is defined as follows: (a) data transfer speed of input means <signal processing speed of coding means (b) data transfer speed of recording means < Signal processing speed of decoding means (c) By setting the data transfer rate of the network <encoding and decoding means, signal processing without stagnation or delay of data between the above means is performed. This can be achieved by determining the load of signal processing in advance from the above condition that the capacity of code data generated by arithmetic codes does not exceed the capacity of input image data. As a result, the buffer memory capacity for matching the data transfer speed between the respective means can be reduced to zero or the minimum capacity necessary for the device configuration.

[0018]

【Example】

(1) Overall Configuration of Apparatus FIG. 1 shows an embodiment of the present invention. The image data input from the scanner 101 is converted into coded data by the coding processing device 105 and stored in the storage device 103 such as a hard disk or a portable storage device while performing speed matching using the buffer memory 104. Here, if the input image data is immediately converted into code data and stored in the code data storage means, there is no need to store the image data of one screen as it is. The storage means is configured by combining a semiconductor memory, a magnetic or optical storage medium, or a plurality thereof. However, when using a semiconductor memory, it is desirable to supplement the power supply with a battery or the like in order to prevent the stored contents from being lost even when the power of the image communication terminal is turned off.

When transmitting code data to a partner terminal,
As shown in FIG. 2, first, it is necessary to confirm the terminal capability of the partner terminal and convert it to code data that can be decoded by the partner terminal. Therefore, the code data stored in the storage device 103 is decoded and coded into code data matching the capability of the partner terminal. In the conversion of the code data, it is sufficient to prepare a buffer memory necessary for encoding and decoding, and there is no need to store image data of one screen or code data.
There is no need for any means. When code data is received from the partner terminal, the data is decoded, encoded for storage again, and stored in the storage device 103, in substantially the reverse of the transmission.

When the code data stored in the storage device 103 is recorded by the printer 102, it is converted into image data by the decoding processing device 106,
And data transfer to the printer 102 while performing speed matching. Here, if the code data is converted into image data and the data is immediately transferred to the printer, there is no need to accumulate one screen of image data, and no means for that is necessary.

(2) Signal Processing Procedure In the image communication using the storage device 103, the execution of input, output and transmission of an image can be dispersed, and the execution time of each can be set arbitrarily. For example, as shown in FIG. 2, by utilizing the fact that there is no restriction on the time for image input, a low-priced drive system with a low paper feed speed, a long exposure time and a low-sensitivity sensor are used. On the other hand, by performing data transmission at the time of transmission according to the transmission rate of the network, there is an effect that the price of the device can be reduced while maintaining the capability as a communication terminal. Similarly, at the time of reception, there is an effect that the price is reduced by using a printer having a low recording speed.

As described above, if the signal processing is executed with a time lag, the load is dispersed and reduced, so that a single processor executes all the processes related to image input, output and transmission. Hardware and software can be configured as described above, and there is an effect that the cost of the apparatus can be reduced.

(3) Configuration of the encoding / decoding device In the image communication terminal, it is essential to adopt a system capable of mutually encoding / decoding for data transmission with the partner terminal. Since the encoding process for transmission is determined in the capability confirmation of the mutual terminal prior to data transmission, the encoding process for transmission must be started after the capability confirmation.

For data storage inside the own device, a unique encoding method can be adopted. However, for data transmission, the stored data is decoded into image data or some intermediate data and then transmitted. Is performed.

FIG. 3 shows an example of the configuration of an encoding / decoding device for executing the above signal processing. Software-based realization is also possible in the form of adding a program memory to the signal processor. The arithmetic coding method can also be realized by software processing with the support of hardware included in the processor. It goes without saying that the signal processing support by hardware may be configured by an internal circuit of the processor or by an external circuit. Further, if the signal processing program stored in the program memory is configured to be downloadable from the outside, it is possible to easily cope with addition of an encoding processing method and modification of the program.

Next, the signal processing speed of the encoding / decoding device will be described. The signal processing speed of the encoding / decoding device that executes the arithmetic code is set according to the following magnitude relation.

(A) Data transfer speed from input means such as a scanner <Signal processing speed of arithmetic code encoding device (b) Data transfer speed to output means such as a printer <Signal processing of arithmetic code decoding device Speed (c) Data transfer speed to / from a transmission means such as a network <Signal processing speed of arithmetic code encoding / decoding device By setting in this way, for example, in (a) above, the When encoding image data, the signal processing speed of the encoding device is faster than the data transfer speed from the input means, so that no stagnation of the image data occurs. This means that there is no need for a buffer memory for temporarily storing image data between the input means and the encoding device. Even if there are restrictions on the device configuration such as timing, the minimum is possible. What is necessary is just to prepare a buffer memory having a capacity. This effect is the same in the above (b) and (c). The conditions (a), (b), and (c) are set based on the condition that the amount of code data by encoding and decoding by arithmetic codes is equal to or less than the amount of image data, This is based on the effect of being able to set the number of steps with high precision in advance.

(4) Number of Stored Screens Since the maximum value of the code data of one screen can be determined in advance, the storage capacity already stored in the storage device 103 and the number of screens that can be stored can be calculated as shown in FIG. . Then, for the user of the image communication terminal, FIG.
By notifying the number of screens by various means as described in (1), there is an effect that an abnormal state such as excess storage capacity at the time of image input can be avoided in advance.

In addition to displaying the number of screens that can be stored,
A display for prompting an instruction on a management method such as saving and erasing of already transmitted code data is displayed, and data management can be performed according to the instruction.

(5) Storage Means As described above, the storage device 103 for storing the code data is configured by combining a semiconductor memory, a magnetic or optical storage medium, or a plurality thereof.
These can be used by a method of fixed installation in the inside of the apparatus in advance, a method of additionally installing the apparatus in accordance with a use situation, a method of a detachable configuration, or the like.
A so-called IC card,
A flexible disk or the like can be used.

It goes without saying that various data other than code data can be stored using such storage means. Using this means, a signal processing program such as an encoding process, communication management data such as a telephone number of a partner terminal,
Control data useful for controlling the image communication terminal, such as the past history of the image communication terminal, can be stored.

(6) Signal Processor By performing signal processing using the storage means, image input from a scanner, image output to a printer, call processing with a partner terminal, call processing and other call processing, and call processing to the partner terminal Many of the encoding processes and the like for data transfer can be executed without time overlap.

This means that the method and timing can be set with little influence on the signal processing and the like executed inside the own device.

Further, the processor for executing the signal processing includes:
Since many of these signal processes can be temporally distributed, the required maximum processing capacity of the processor can be reduced, and the cost of the apparatus can be reduced.

(7) Network Function For mutual communication with a partner terminal, a signal processing procedure must be performed based on a predetermined protocol. The terminal capabilities to be confirmed by the mutual terminals include the screen size, the line density, and the like, in addition to the coding method. Then, as described above, communication is not established unless the mutual terminal capabilities match. For example, whether to encode and transmit image data as a multi-level signal or a binary signal must be set in advance based on the compatibility of the capabilities of the mutual communication terminals. If the stored image data is a multi-level signal even though it is set to be coded and transmitted by a binary signal, after performing signal conversion by means for converting the multi-level signal to a binary signal, Perform signal processing for coded transmission.

However, in general, if a network for performing transparent data transmission is provided with some data conversion means as shown in FIG. 6 so as to function so as to match the terminal capabilities of the mutual terminals, it is not always necessary to provide mutual conversion. Matching of terminal capabilities is no longer a prerequisite for starting communication.

Taking the encoding method as an example, the storage device 103
If the code data stored in the network device matches the capability of the data conversion means of the network, the data can be sent out without being converted to the code data corresponding to the partner terminal. Therefore, if the apparatus configuration is based on the premise that the data conversion means of the network is used, there is no need for a means for converting to an encoding method corresponding to the partner terminal, so that the load on signal processing can be reduced and the apparatus price can be reduced. Effective for reduction.

Similarly, by providing a network for data conversion means such as screen size and line density, it is effective in reducing the device price of the terminal.

Further, by providing transmission data storage means in the network, transmission to a plurality of terminals, setting of transmission time, retransmission when a partner terminal is busy, etc. are realized as a network function, and the terminal device is provided. The price can be reduced.

(8) Improvement of image quality of image data Image enhancement such as edge enhancement, density conversion, and noise removal can be performed by signal conversion corresponding to image characteristics. In addition, efficient compression can be performed by encoding processing corresponding to image properties. In order to perform such signal processing, it is essential to accurately determine the image properties.

Therefore, for the image stored in the storage means, the discrete cosine transform which is a part of the coding means for the multi-valued image as shown in FIG. It can be carried out. The discrete cosine transform is a subset of the Fourier transform and can measure a frequency component of an image signal. Therefore, since the binary image has a relatively high frequency component and the multi-valued image has a relatively low frequency component, the conversion result is determined to distinguish the binary image from the multi-valued image. It can be performed.

In this way, it is possible to select an image quality improvement and encoding method for the image stored in the storage means, perform signal processing, and then transmit the image to the partner terminal.

As an example for improving the image quality, there is a method of setting a window surrounding a target pixel as shown in FIG. 8 and performing a filtering process using weighted coefficients. But,
If the calculation is not performed using the coefficient corresponding to the image property, the image quality may be degraded. Therefore, by providing a means for selecting an appropriate coefficient from the determination result based on the frequency component, a high-quality image can be obtained.
In addition, by executing the operation of the filter processing using means for discrete cosine transform, it is possible to suppress an increase in the device scale.

(9) Hierarchical Display of Stored Images Hierarchical encoding / decoding using arithmetic codes, code data storage, and image display means are used to store data in the storage means. Images can be displayed on the screen to check the contents. Further, by utilizing a hierarchical image display as shown in FIG. 9 and displaying a plurality of stored images at a reduced size and simultaneously, it is possible to easily search for a target image.

As shown in FIG. 10, the image display means displays the screen to be reproduced and displayed hierarchically and the stage of the hierarchical reproduction at the same time, thereby assisting the operator.

(10) Edit Processing of Image Using the image stored in the storage means as a material, editing processing can be performed to create a new image and stored in the storage means again. The image used as the material may be not only an already stored image but also a newly input image, and may be a single image or a plurality of images. In these images,
Editing processing such as addition, correction, compounding, and deletion can be performed by, for example, interactive processing with an operator while displaying the information on a display device. The newly created image can be stored in the storage means again, and can be used for output to a printer or the like, transmission through a network, or the like.

Even when the image from the input means is a color image, exactly the same signal processing can be performed.

FIGS. 12 and 13 show examples of the configuration of a color facsimile which realizes the above-mentioned features. The input means and output means perform color image signal processing, but the other terminal is not always capable of handling color images, and is configured to be able to execute encoding / decoding processing for monochrome images. The capability of the partner terminal is confirmed in advance by transmission control. Also,
A means for editing and processing is prepared so that the image stored in the storage means can be reused.

[0049]

According to the present invention, since the maximum capacity of the code data of one screen can be set in advance, the number of screens that can be stored in the storage means can be determined in advance, and the unstored capacity is calculated from the capacity already stored. Further, the number of screens that can be stored can be displayed.

Further, according to the present invention, the maximum capacity of one-screen code data can be set in advance, so that the data transfer time per one screen in inputting an image from a scanner, outputting an image to a printer, and transmitting / receiving to / from a partner terminal. Can be set, the buffer memory for matching the data transfer speed can be minimized.

Further, by providing the above-mentioned buffer memory for speed matching, the buffer memory for other purposes can be made unnecessary.

Further, according to the present invention, the maximum capacity of one-screen code data can be set in advance, so that the time required for signal processing of the coding means, decoding means, storage means, transmission control means with the partner terminal, etc. Can be calculated in advance, so that the signal processing procedure in the image communication can be designed with reference to the above time. By executing signal processing such as encoding means, decoding means, storage means, and transmission control means with a partner terminal without overlapping in time, the load of signal processing can be reduced and the equipment configuration can be reduced. Effective for simplification.

[Brief description of the drawings]

FIG. 1 is an example of a configuration diagram for implementing the present invention.

FIG. 2 is an explanatory diagram of a procedure for checking terminal capabilities.

FIG. 3 is an example of a signal processing procedure.

FIG. 4 is a configuration example of an encoding / decoding device.

FIG. 5 is an explanatory diagram of a method for calculating the number of storable screens.

FIG. 6 is a display example of the number of screens that can be stored.

FIG. 7 shows an embodiment of a network protocol conversion function.

FIG. 8 shows a coding method of a multilevel image.

FIG. 9 shows an embodiment of a filter process for improving image quality.

FIG. 10 is a diagram illustrating the principle of a hierarchical encoding process.

FIG. 11 is an example of a hierarchical screen display.

FIG. 12 is a configuration example of a color facsimile (storage transmission).

FIG. 13 is a configuration example of a color facsimile (receiving and storing).

[Explanation of symbols]

101: scanner; 102: printer; 103: storage device; 104: buffer memory; 105: encoding device; 106: decoding device.

Claims (19)

(57) [Claims] An image communication terminal that encodes image data and transmits the encoded data to a partner terminal and / or decodes the encoded data transmitted from the partner terminal to reproduce the image data. First encoding means for storing the arithmetically coded data, first decoding means for decoding the accumulated arithmetic coded data, and a decoding procedure of the other terminal. Recognizing means, and a second encoding unit that encodes according to the recognized decoding procedure.
And a second decoding means for decoding the coded data sent from the partner terminal. 2. An encoding / decoding apparatus according to claim 1, wherein said image data is inputted by an input means, arithmetically encoded and stored in said storage means, and said image data is transmitted to said counterpart terminal. An encoding / decoding apparatus characterized in that the arithmetic encoding data accumulated in the accumulating means is encoded by the second encoding means in accordance with the decoding procedure of the partner terminal at a timing different in time. 3. The encoding / decoding device according to claim 1, wherein the process of storing the code data sent from the partner terminal in the storage means and the process of recording the image data by the recording means are time-consuming. An encoding / decoding device characterized by different timings. 4. An encoding / decoding apparatus according to claim 1, wherein said first encoding means has a processing speed for arithmetically encoding the image data inputted by said input means without stagnation. An encoding / decoding apparatus, wherein the first decoding means has a processing speed for decoding the image data recorded by the recording means without delay. 5. The encoding / decoding device according to claim 1, wherein said first encoding / decoding means and said second encoding / decoding means stay transmission data input or output via a network. Alternatively, an encoding / decoding device having a processing speed for encoding or decoding without delay. 6. An encoding / decoding apparatus according to claim 1, wherein said first storage means has a smaller capacity than one-screen image data for accumulating the image data inputted by said input means, and said arithmetically encoded data is stored in said first storage means. And a second storage unit having a larger capacity than one-screen image data for storing the encoded data. 7. The encoding / decoding device according to claim 6, wherein said first storage means is a semiconductor memory, and said second storage means is a semiconductor memory, a magnetic storage medium, or an optical storage medium. An encoding / decoding device using at least one of the following. 8. An encoding / decoding apparatus according to claim 1, wherein said second storage means is detachable from said encoding / decoding apparatus. 9. An encoding / decoding apparatus according to claim 1, wherein said storage means has an encoding processing program executed by an arithmetic unit, and said encoding means transmits said encoding program to said arithmetic unit prior to encoding processing by said arithmetic unit. An encoding / decoding apparatus which transfers the encoding processing program to storage means accessed by a signal line composed of an address and data. 10. The encoding / decoding apparatus according to claim 1, wherein after confirming the decoding procedure of the partner terminal, the arithmetic code data stored in said storage means is decoded to generate code data which can be decoded by the partner terminal. An encoding / decoding device for encoding and transmitting. 11. An encoding / decoding apparatus according to claim 1, wherein said second encoding means encodes the data of the monochrome binary image using at least one of MH, MR, and MMR. An encoding / decoding device characterized by the following. 12. An encoding / decoding apparatus according to claim 1, wherein said second encoding means encodes multi-valued image data using a discrete cosine transform. apparatus. 13. An encoding / decoding apparatus according to claim 1, wherein said means for outputting code data to a network, said second encoding means for creating code data for transmission, and a transmission time are minimized. Means for selecting a coding method of the second coding means for achieving the above. 14. An encoding / decoding apparatus according to claim 1, wherein a signal conversion process for an image stored in said storage means is performed by using a discrete cosine transform result calculated by said second coding means. An encoding / decoding device provided with a selection unit. 15. An encoding / decoding apparatus according to claim 1, wherein said measuring means measures an available storage capacity of said storage means for arithmetic code data, and the available storage capacity is based on a measurement result of said measuring means. An encoding / decoding apparatus comprising: means for calculating the number of screens that can be input from the input means; and means for displaying the calculation result. 16. An encoding / decoding apparatus according to claim 1, wherein said comparing means compares a free storage capacity of said storage means with a reception storage capacity for receiving code data from a partner terminal. Detecting means for detecting that the received storage capacity exceeds the free storage capacity of the storage means based on the result of the output means, output means for outputting the detection result of the detection means, and An encoding / decoding device, comprising: input means for inputting an instruction. 17. An encoding / decoding apparatus according to claim 1, wherein said encoding means encodes an arithmetic code, and said decoding means decodes the arithmetic code encoded by said encoding means into original image data. Means, and storage means for storing code data handled by the encoding means and the decoding means, wherein the code data stored in the storage means are hierarchically decoded, and the image data and the image hierarchy level are the same. An encoding / decoding device for displaying on an image display means. 18. The encoding / decoding apparatus according to claim 1, wherein said input means for processing multi-valued image data, said first means for processing multi-valued image data.
Encoding means, the storage means and the first decoding means, the second encoding means for processing binary image data, and the conversion means for converting multi-valued image data into binary image data. An encoding / decoding device characterized by the above-mentioned. 19. An encoding / decoding apparatus according to claim 1, wherein said means for displaying image data obtained by decoding the code data stored in said storage means by said first decoding means is displayed. An encoding / decoding device comprising: an editing unit for editing image data; and a data transfer unit for transferring image data as a result of the editing process to the input unit again.