Patent ID: 7574004

Claim:
An image display method, characterized in that an image signal is inputted, and when the inputted image signal is to be displayed or outputted, changeover of a display operation condition is performed based on a value of encrypted operation condition control information having a predetermined attribute in order to display or output the image signal that was inputted, whereby the predetermined attribute is varied according to the place and/or time of display or output of the image signal, and whereby a management source analyzes a pattern of disorder in an illegal copy of the image signal as displayed to determine a predetermined attribute associated with the illegal copy and cross-references the predetermined attribute with its corresponding place and/or time to determine the place and/or time of creation of the illegal copy, whereby no image is superimposed on the displayed image signal and the pattern of disorder results solely from the manner in which the image signal is reproduced as a result of the changeover of a display operation condition which is based on a value of the encrypted operation condition control information.