1. A feature image detecting method of detecting a feature image and presenting a detection result, comprising: storing a correction case example with respect to the feature image in a database; detecting whether or not the feature image is contained in an inputted video to be examined; if the feature image is contained, retrieving the database by using a reason of the feature of the detected feature image as a key, and obtaining a correction case example; applying the correction case example to a feature portion of the image and creating a correction proposal, and outputting the reason of the feature, the feature portion, and the correction proposal of the detected feature image for the purpose of correction of the feature image.