In some implementations, a transaction card security system may detect a transaction card in an image, and may perform image processing to identify one or more character sequences or one or more designs that appear on the transaction card. The one or more character sequences or the one or more designs may identify an institution associated with the transaction card and/or a cardholder associated with the transaction card. The transaction card security system may identify the institution or the cardholder associated with the transaction card based on the one or more character sequences or the one or more designs, and may perform one or more actions relating to security of the transaction card based on detecting the transaction card in the image and identifying the institution or the cardholder associated with the transaction card.