Systems and methods are provided for using imagery depicting a timekeeping device to determine a clock offset for a particular image capture device. The clock offset can be used to correct timestamps associated with one or more images captured by such image capture device. One example method includes analyzing imagery depicting at least in part a timekeeping device to determine a first time displayed by the timekeeping device in the imagery. The method includes determining whether the first time comprises a 12-hour value or a 24-hour value. The method includes, when it is determined that the first time comprises a 12-hour value, determining a corresponding 24-hour value for the 12-hour value based at least in part on information contained within a plurality of images. The method includes determining a clock offset between the 24-hour value and the first timestamp. One example system includes a timestamp correction engine for correcting timestamps.