Image proof method, and method of being act advertisement image before application program acts

PURPOSE: An image authentication method is to authenticate whether an actual image stored in an image file is equal to the original image. CONSTITUTION: An image authentication method is to authenticate an image by encoding and decoding an image, and the method to execute an application program blocks the execution of the application program if a desired advertisement image is not displayed. The method to execute the application program includes: the first step of authenticating whether an image of a first advertisement group selected at random is equal to the advertisement image distributed by a sponsor; the second step of displaying by replacing the screen images with the image of the first advertisement group if the authentication is approved; the third step of authenticating whether an image of a second advertisement group selected at random is equal to the advertisement image distributed by the sponsor; the forth step of displaying by replacing the screen images with the image of the second advertisement group and executing the application program if the authentication is approved; and stopping the execution of the application program when the authentication of the third step is denied.