An image transfer system has an extracting section that extracts image areas from a document image read by a reading section. A digital signature providing section provides sender's digital signatures to the image areas according to degrees of secrecy. An image file creating section creates an image file including image areas with the sender's digital signatures provided by the digital signature providing section and a sending section sends the image file to a receiving section. A digital signature acquiring section acquires receiver's digital signatures for restricting image areas to be presented to a user. An image area selecting section selects image areas to be presented to the user in accordance with the sender's digital signatures in the image file received by the receiving section and the receiver's digital signatures acquired by the digital signature acquiring section. An output section outputs image areas selected by the image area selecting section.