1. A method executed by a processor of the server, the method comprising: obtaining an image transmitted, through a network, from any of at least one terminal having a function of capturing an image or obtaining an image from another device; calculating a probability that the obtained image includes a certain imaging target; adding, if the probability is higher than a first threshold, information indicating the certain imaging target to the image; not adding, if the probability is lower than a second threshold, the information indicating the certain imaging target to the image; and transmitting, if the probability is equal to or higher than the second threshold and if the probability is equal to or lower than the first threshold, the image and request reception information for requesting addition of the information to the image to any of the at least one terminal through the network; wherein the first threshold and the second threshold are different between when the probability is calculated using a calculator constructed using less than a certain number of images to which the information has been added and when the probability is calculated using a calculator constructed using the certain number of images or more to which the information has been added.