US Patent 7581115 Information processing method, apparatus, and information processing program

Even when encoded (compressed) image data appended with an error-detecting code is encrypted, the apparatus which receives and reproduces that image data can execute a normal process without any insignificant re-send request and the like. To this end, encoded image data is input, and first error-detecting encoding information contained in its header is checked to determine whether or not an error-detecting code is appended. If it is determined that the error-detecting code is appended, the first error-detecting encoding information is changed to indicate the absence of an error-detecting code, and is saved as second error-detecting encoding information. Then, the encoded image data is encrypted.