JPH04291826A - Coding transmitter - Google Patents

Abstract

PURPOSE:To provide a coding transmitter in which a generated data quantity is reduced against a characteristic change in an information source and a high transmission efficiency is maintained. CONSTITUTION:This coding transmitter is provided with plural coding sections 2A-2N coding the information from an information source 1 with a different coding system, a comparison deciding section 3 comparing the data quantity of the result of coding of the coding sections 2A-2N, a selective section 4 selecting the result of coding to be a minimum data quantity by the comparison discrimination section 3, an identification code discrimination section 6 adding the identification code representing the coding system to the selected result of coding, and a transmission section 7 sending the result of coding with the identification code added thereto through a transmission line 8.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a coded transmission device.
Especially regarding source encoding.

0002

2. Description of the Related Art Generally, in a communication system, when transmitting information from an information source to a receiver, source encoding is performed in order to minimize the amount of data transmitted on a transmission path. In order to shorten the communication time, it is necessary to shorten both the transmission time on the transmission path and the time required for encoding/decoding. Among these, the effect of reducing the transmission time due to information source encoding is much larger than the encoding/decoding time.

[0003] Various methods for encoding information sources are known, one of which is shortest encoding called Huffman encoding. This is done by setting the appearance frequency distribution of information units (for example, byte units for code information, run lengths for image information, etc.) in the information source in advance, and then This method assigns a code with a shorter word length. The code obtained by this is called a shortest code or Huffman code. In communication systems, once the source encoding scheme is set,
It is normal that it will be used permanently from then on.

However, the frequency of appearance of each information unit in an information source varies depending on the characteristics of the transmission object, that is, whether the transmission object is a general text, a program code, a data string, a line drawing, a photograph, etc. In addition, when information is encrypted and transmitted as is the case these days, even if the information sources are of the same type, the appearance frequency distribution of information units can unexpectedly change from the initially set shortest code. This is often the case. In such a case, the amount of generated data increases and the transmission efficiency decreases significantly.

[0005]

[Problems to be Solved by the Invention] As mentioned above, in conventional communication systems, the information source encoding method is fixedly used, so when the appearance frequency distribution of information units in the information source changes, the generated data There was a problem in that the amount increased and the transmission efficiency decreased significantly. SUMMARY OF THE INVENTION An object of the present invention is to provide an encoding and transmitting apparatus that can maintain high transmission efficiency by reducing the amount of data generated from an encoding unit in response to changes in characteristics of an information source.

[0006]

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a plurality of encoding units that encode information from an information source using different encoding methods, and reduces the amount of data of these encoding results. , select the encoding result of one encoding unit determined to have the smallest amount of data, and transmit it with identification information indicating the encoding method of the encoding unit that provides the encoding result. It is characterized by the following.

[0007]

As described above, in the present invention, from among the encoding results of a plurality of encoding units using different encoding methods, the encoding result of the encoding unit with the smallest amount of data is selected. As a result, the amount of data transmitted on the transmission path is always minimized regardless of the characteristics of the information source, improving transmission efficiency.

[0008]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of the transmitting side in an encoding and transmitting apparatus according to an embodiment of the present invention, and FIG. 2 is a block diagram of the receiving side.

[0009] In FIG. 1, an information source 1 provided on the transmitting side generates code information and image information, which are communication information, and encodes the generated information in multiple ways for source encoding. 2A to 2N. Encoding section 2A
~2N have different encoding systems and operate independently and in parallel. The encoding results of these encoding units 2A to 2N are supplied to a data amount comparison and determination unit 3 and a selection unit 4.

[0010] The data amount comparison/judgment section 3 includes the encoding sections 2A to 2A.
The data amount (code amount) of the 2N encoding result is compared and determined, and the comparison determination section with the smallest data amount is detected. The determination result of the data amount comparison and determination section 3 is supplied to the selection section 4 and the identification code generation section 5. The selection unit 4 includes the encoding units 2A to 2A.
Control is performed to select the encoding result of the encoding section whose data amount is determined to be the smallest by the data amount comparison and determination section 3 out of 2N.

The identification code generation section 5 generates an identification code indicating the encoding method of the encoding section that provides the encoding result for which the data amount comparison and determination section 3 determines that the amount of data is the smallest. The identification code addition section 6 adds the identification code from the identification code generation section 5 to the encoding result selected by the selection section 4. Note that it is only necessary to add the identification code when the selection section 4 is switched.

[0012] The transmitting section 7 subjects the data string consisting of the encoding result and the identification code outputted from the identification code addition section 6 to appropriate transmission path encoding, for example, and sends it to the transmission path 8 . The transmission line 8 may be wired or wireless, and its communication form may be either parallel or series.

On the other hand, on the receiving side shown in FIG. 2, the receiving section 11 receives the transmission signal sent from the transmitting section 7 of FIG. In this case, the process opposite to transmission line encoding, that is, transmission line decoding, is performed, and the decoded output is sent to the decoding section 14 and the identification code extraction section 12. The identification code extraction section 12 extracts an identification code indicating the encoding method included in the transmission signal, and sends it to the encoding control section 13 . The encoding control unit 13 controls the decoding unit 1 according to the identification code extracted by the identification code extraction unit 12.
Control 4.

The decoding section 14 performs decoding using one decoding method selected from a plurality of decoding methods corresponding to the encoding methods of the plurality of encoders 2A to 2N on the transmitting side in FIG. It is configured so that it can be done. Under the control of the decoding control unit 13, the decoding unit 14 is set to a decoding scheme that corresponds to the encoding scheme used on the transmitting side, and performs information source decoding, which is the reverse process of the encoding unit. By doing this, the information output from the information source 1 in FIG. 1 is restored to the same information as the expression format of the information source 1. The restored information is given to the receiver 15, where it is subjected to appropriate information processing and then subjected to output processing such as recording and display.

[0015] In this way, by selecting the encoding result of the encoding unit with the smallest amount of data among the encoding results of the plurality of encoding units 2A to 2N using different encoding methods on the transmitting side, the encoding Efficiency can always be kept high, thereby reducing the transmission time on the transmission path 8 and the communication time.

Next, the characteristics of the information source 1 and the encoding units 2A to 2
The relationship between N encoding methods will be explained. Consider code information and image information as communication information generated by information source 1. Code information includes information that encodes Japanese sentences and English sentences, and binary data (for example, C
(Information such as AD data where the appearance frequency of each code cannot be specified). Huffman encoding is used as an encoding method for such code information.

However, even when the communication information generated by the information source 1 is the same code information, the frequency of appearance of character codes differs greatly between, for example, Japanese and English texts, so the encoding efficiency also differs depending on the encoding method. Therefore, encoding units 2A to 2N
Encoding sections using various different Huffman encoding methods are prepared, and the data amount comparison/determination section 3 and selection section 4 select the encoding section using the Huffman encoding method that minimizes the data amount of the encoding result. By selecting the output, the amount of generated data can always be reduced regardless of the type of code information.

On the other hand, typical image information is image data (referred to as facsimile data) obtained by reading a document with a facsimile machine, and this includes facsimile data of general document images and binary images such as drawings. facsimile data, halftone image facsimile data such as photographs, and facsimile data of halftone photographs used in newspapers.

Encoding methods for such image information are broadly classified into one-dimensional methods and two-dimensional methods. The one-dimensional method is a method in which each line of an image signal is encoded independently, and includes methods such as run-length coding (Weyl code, modified Huffman code) and run-length predictive coding. The two-dimensional method is a method that encodes two lines at once when the correlation between lines of the image signal is strong, or encodes only the difference between the current line and the previous line. There are several methods such as run-length encoding, differential conditional run-length encoding, and predictive run-length encoding.

The optimal encoding method differs depending on whether the facsimile data is a document image, a halftone image, or a halftone image. Therefore, as the encoding units 2A to 2N,
Encoders using the various different encoding methods listed above are prepared for image information, and the data amount of the encoded result is determined by the data amount comparison/judgment section 3 and selection section 4, as in the case of code information. By selecting the output of the encoding unit using the minimum encoding method, the amount of generated data can always be reduced regardless of the type of image information.

[0021] Furthermore, the data comparison/judgment section 3 and the selection section 4
It is not necessarily necessary to always operate to select the encoding result of the encoding unit with the minimum amount of data, and for example, the selection operation may be performed at regular intervals. By doing this, for example, when the information source 1 generates facsimile data from a document containing various image information mixed together, the operation may become unstable due to frequent switching of the encoding method, and the code may become unstable. It is possible to avoid a decrease in encoding efficiency due to the identification code added to the encoding result when switching the encoding method.

Furthermore, in the embodiment, the decoding section 14 selectively takes a plurality of decoding methods on the receiving side, but the decoding section 14 selectively uses a plurality of decoding methods corresponding to the plurality of encoding sections 2A to 2N on the transmitting side. A conversion section may also be provided.

[0023]

As explained above, according to the present invention, a plurality of encoding units with different encoding methods are prepared, and the encoding result of the encoding unit with the smallest amount of data is selected and encoded. By adding identification information indicating the encoding method and transmitting it, the amount of generated data can be constantly reduced regardless of changes in the characteristics of the information source, that is, the type of information, and high encoding efficiency can be obtained, reducing transmission time. It becomes possible to shorten the time.

[Brief explanation of the drawing]

[Fig. 1] Block diagram of the transmitting side of a coding transmission device according to an embodiment of the present invention

FIG. 2 is a block diagram of the receiving side of the encoding and transmitting device.

[Explanation of symbols]

1...Information source
2A to 2N... Encoding unit 3... Data amount comparison/judgment unit
4... Selection section 5... Identification code generation section
6...Identification code addition section 7...Transmission section
8...Transmission line 11...Receiving section
12...Identification code extraction section

Claims (1)

[Claims] Claims: 1. A plurality of encoding means using different encoding methods for encoding information from an information source; means for comparing the amount of data of the encoding results of the plurality of encoding means; means for selecting the encoding result determined to be the amount of data; means for adding identification information indicating the encoding method of the encoding means for providing the encoding result to the encoding result selected by the means; and this means An encoding and transmitting device comprising means for transmitting an encoding result to which the identification information is added.