1. A method for automatic white balance, comprising: obtaining, by a front end device of a video monitoring system, a white region for performing automatic white balance; generating, by the front end device, at least one cluster by clustering statistical points within the white region of a to-be-detected image; in case that the number of statistical points within one of said clusters is greater than a preset threshold, determining, by the front end device, the cluster as a target cluster, and determining, by the front end device, the statistical points within the target cluster as white points; and determining, by the front end device, a white balance gain of the to-be-detected image based on the target cluster.