Title:
CODING DECODING METHOD AND DEVICE THEREFOR
Document Type and Number:
Japanese Patent JP3131051
Kind Code:
B2
Abstract:
PURPOSE: To keep the information secrecy by setting an incident probability width applied for arithmetic coding to a value other than a standard value so as to device the method such that coded information is not properly decoded when the initial value of the incident probability width is not known.
CONSTITUTION: The unity is used for an initial value of an appearance probability width area A and when the initial value is revised at coding, since the initial coding state is changed, a different coding result from the case that the initial value is set to the unity is obtained. For example, a picture on a type original is read by a scanner and a coding decoding section 7 with the area A whose initial value is set to 0.6 applies coding and compression to the obtained picture signal. The picture information obtained therefrom is decoded by using the coding decoding section 7 in which the initial value of the area A is set to the unity being the standard value. When a plotter 5 is used to print out the picture of the obtained picture signal, since the condition at the coding and that at the decoding differ, a picture indicating almost noise is printed out. That is, transmission picture information is ciphered by using the different initial value of the area A from the standard value.
Inventors:
Yasuyuki Nomizu
Application Number:
JP28352592A
Publication Date:
January 31, 2001
Filing Date:
September 30, 1992
Export Citation:
Assignee:
株式会社リコー
International Classes:
H03M7/40; H04N1/41; H04N1/44; (IPC1-7): H03M7/40; H04N1/41; H04N1/44
Domestic Patent References:
| JP340658A | ||||
| JP556267A |
Attorney, Agent or Firm:
Makoto Monda