1. A light metering method, comprising: acquiring a touch screen point inputted by a user; identifying an initial light metering area based on an image displayed on a touchscreen, the initial light metering area containing the touch screen point; segmenting the initial light metering area into a background region and an object region containing the touch screen point, wherein the segmenting includes: calculating color distances between the touch screen point and to-be-tagged points adjacent to the touch screen point based on an RGB color value of the touch screen point and RGB color values of the to-be-tagged points adjacent to the touch screen point; and calculating color distances between image boundary points of the initial light metering area and to-be-tagged points adjacent to the image boundary points based on RGB color values of the image boundary points and RGB color values of the to-be-tagged points adjacent to image boundary points; and performing light metering on image points within the object region.