SECRECY METHOD FOR PICTURE DATA

摘要

PURPOSE:To reduce the processing time and the cost by ciphering only a partial area in a picture data desired especially to be handled with confidentiality. CONSTITUTION:A partial area 2 desired to be handled with confidentiality in an original picture 1 is ciphered by using a cryptographic key 3. A picture 4 after secrecy processing is processed in such a way that areas other than the partial area 2 of the original picture 1 is unprocessed and a ciphered partial area 5 is embeded to a position where the partial area 2 has been resident. The picture 4 after secrecy processing is sent through a general transmission line 10. In order to obtain original picture information from the sent picture, the ciphered partial area 5 is decoded by using a decoding key 6 and a decoded partial area 8 is embeded to a position where the ciphered partial area 5 has been resident. Since ciphering is processed only to part in the picture data, the processing time is less than the case with ciphering the entire picture and the cost is reduced.