Filtering Content In An Online System Based On Text And Image Signals Extracted From The Content

The disclosure relates (a) a method and computer program product for training a content classifier and (b) a method and computer program product for using the trained content classifier to determine compliance of content items with a content policy of an online system. A content classifier is trained using two training sets, one containing NSFW content items and the other containing SFW content items. Content signals are extracted from each content item and used by the classifier to output a decision, which is compared against its known classification. Parameters used in the classifier are adjusted iteratively to improve accuracy of classification. The trained classifier is then used to classify content items with unknown classifications. Appropriate action is taken for each content item responsive to its classification. In alternative embodiments, multiple classifiers are implemented as part of a two-tier classification system, with text and image content classified separately.