Abstract: In a digitalized facsimile transmission system, (k) number of scanning lines (k=2 or 4) are encoded to a relative address code and the next scanning line is encoded to a run length code, and each scanning line has the related synchronization code pattern corresponding either said relative address code or said run length code. Thus, the effect of a transmission error is restricted within one scanning line when that error occurs in the scanning line encoded to run length code, or k lines when that error occurs in the scanning line encoded to relative address code. The value (k) is switched between k=2 and k=4 according to the instantaneous quality of a communication line. When the quality is good, k=4 is selected, and when the quality is bad, k=2 is selected. The reception side can switch the decoding systems between relative address decode and run length decode, by being controlled through the related synchronization code patterns.

Abstract: A transmission speed switching system for a transmission system having at each party of said transmission system a plurality of data MODEMs of different transmission speeds b.sub.1, b.sub.2, . . . b.sub.n, in which a carrier is modulated by a code train at intervals of a time S equal to a common multiple of symbol intervals S.sub.1, S.sub.2, . . . S.sub.n respectively corresponding to the transmission speeds in a manner to obtain a predetermined modulated wave which instructs said MODEMs of the other party the switching to a specified one of the transmission speeds, and in which the modulated wave is transmitted to the receiving station so that a demodulated code by a demodulator of any of the transmission speeds may be interpreted as the code train indicating the specified transmission speed to be selected by the receiving station, thereby switching the transmission speed to the specified one corresponding to the result of the interpretation.

Abstract: A facsimile signal coding system, in which a facsimile signal is divided into a plurality of scanning line groups each including a predetermined number of scanning lines. A substantially central one of the scanning lines of each group is encoded by a coding method without referring to information of a scanning line adjacent to the central scanning line. Information of the remaining lines above the central scanning line is sequentially encoded upwardly from the central scanning line using information of the just precedently encoded line as reference information. Information of the remaining lines below the central scanning line is sequentially encoded downwardly from the central scanning line using information of the just precedently encoded line as reference information.

Abstract: A method for coding addresses of information change picture elements each having information different from that of the immediately preceding picture element in a facsimile signal obtained by successively scanning an original picture, in which the information change picture elements are classified into deviation change points each having a high correlation to a final reference change point selected from coded information change picture elements, and new change points each having substantially no correlation to the final reference change point. The deviation change points are coded to indicate the direction and length of each deviation thereof from the corresponding final reference change point. The new change points are coded to indicate each distance thereto from the immediately preceding information change picture element.

Abstract: A facsimile signal converter for converting an input facsimile signal into an output facsimile signal having a scanning line density different from that of the input facsimile signal. A table circuit is provided for developing white and black states of each output picture element of the output facsimile signal in correspondence to a predetermined number of combinations of states of reference picture elements and the geometric relation between the reference picture elements and the output picture elements. The reference picture element corresponds to at least one input picture element of the input facsimile signal adjacent to each output picture element of the output facsimile signal in consideration of a state of superimposing an input pattern on an output pattern indicated respectively by the input facsimile signal and the output facsimile signal.

Abstract: A method for interline-coding a facsimile signal, in which information of scanning lines of the input facsimile signal is alternately divided into information of at least one first unit line and information of at least one second unit line. A first one of the first unit lines is first coded in accordance with a predetermined coding principle. The information of the next one of the first unit lines is secondly coded in accordance with a predetermined coding principle prior to coding of information of the first one of said second unit lines. The information of the first one of the second unit lines is thirdly coded by two-dimensional predictive coding using, as reference information, the information of the first one and the next one of the first unit lines. The operations of the second coding and the operation of the third coding are repeatedly achieved thereafter.

Abstract: A facsimile signal transmission system, in which a coder is provided for coding an input facsimile signal for each information block of picture elements on a predetermined number of scanning lines. A counter is provided for counting the number of bits of each coded output corresponding to the picture elements of the predetermined number of scanning lines. Dummy codes are added to the coded output of the coder to increase the number of bits of the coded output to be larger than a reference bit number predetermined in consideration of the subscanning time at the receiving side in a case where the count result of the counter is smaller than the reference bit number.

Abstract: A method for coding a facsimile signal, in which addresses of information change picture elements each having information different from the immediately preceding picture element on the same scanning line of a facsimile signal are firstly coded for each scanning line to develop a first coded output. In response to the first coded output, the relative distance of each of the information change picture elements to a final reference change point which is selected from information change picture elements on the scanning line including the instant information change picture element to be coded or on at least one immediately preceding scanning line is secondly coded to develop a second coded output. The number of successive information change picture elements having the zero value of the relative distance or the order number of information change picture elements are thirdly coded for each scanning line in response to the second coded output.

Abstract: A facsimile signal coding method, in which information change picture elements are classified into two kinds of change points according to the information change directions. In case of the information change picture element having an information change from white to black, the relative distance between an instant information change picture element and a reference information change picture element selected from information change picture elements on the same scanning line or at least one immediately preceding scanning line is coded. In case of the information change picture element having an information change from black to white, the distance between an instant information change picture element to be coded and the immediately preceding information change picture element is predicted on the basis of information of a run already coded, so that an error between the predicted value and the run length of the instant run is coded.

Abstract: A facsimile signal coding system for successively coding runs of black and white signals included in a facsimile signal obtained by scanning an original picture, in which the length and position on a scanning line of the runs of the black or white signal to be indicated by encoded codes are temporarily stored in a memory. Information of the run of the same state signal as an instant run of black or white signal to be coded and close to the instant run is taken out as reference run information from the memory. The length of the instant run of the black or white signal to be coded is predicted on the base of the reference run information. An error between the predicted run length and the length of the instant run of black or white signal to be coded is coded. When the error exceeds a predetermined value, the length of the instant run of the black or white signal may be coded in place of the error.

Abstract: A system for receiving an input facsimile signal sometimes added with dummy codes for each predetermined number of scanning lines by the use of a decoder for decoding the input facsimile signal for each information block of picture elements on the predetermined number of scanning lines. The number of bits of the input facsimile signal corresponding to the picture elements of the predetermined number of scanning lines is counted by a counter. When the count result of the counter is smaller than a reference bit number predetermined in consideration of the subscanning time of a receiver, the subscanning of the receiver is omitted. In this case, an operation of feeding a recording paper of the receiver may be effected.

Abstract: A signal compression system for efficient transmission of an input binary digital signal, in the form of a binary pulse signal, in which bit polarity reversal is checked after sampling for a predetermined number of bits of the sampled binary pulse signal. In a case of detection of any bit polarity reversal, the sampled binary pulse signal is sent out into a converted output pulse signal for the predetermined number of bits. In a case of non-detection of any polarity reversal, the number of bits or the number of bit blocks having no polarity reversal is coded as a coded pulse signal and sent out into the converted output pulse signal. A coded pulse signal is distinguished, the the converted output pulse signal, from the binary pulse signal by at least one flag bit.

Abstract: A system for coding information change picture elements in a facsimile signal, which is employed for coding the address of each information change picture element assuming information different from that of an immediately preceding picture element on each scanning line. A distance between the information change picture element and a final reference information change picture element selected from the information change picture elements of an immediately preceding scanning line and, if necessary, said scanning line is encoded in a manner to minimize the number of bits of each code word.

Abstract: A system for coding two-dimensional information of M lines and N columns, in which two-dimensional information of M lines and U columns is predetermined as a basic block. If any column information in the basic block has an information change with respect to column information immediately preceding it, information in the basic block is coded. If each column information in the basic block has no information change with respect to the column information immediately preceding it, information corresponding to the number of columns of the basic block and the number of subsequent columns having no information change is coded. Two-dimensional information obtained after the computation operation of a correlation function between an instant bit of information and an immediately preceding bit of information in at least either of the line direction and the column direction may be applied as the input of this system.

Abstract: A system for coding information change picture elements in a facsimile signal, which is employed for coding the address of each information change picture element assuming information different from that of an immediately preceding picture element on each scanning line. A distance between the information change picture element and a final reference information change picture element selected from the information change picture elements of an immediately preceding scanning line and, if necessary, said scanning line is encoded in a manner to minimize the number of bits of each code word.