1. An image obtaining method, which is applied to an electronic device, the electronic device comprising an image capturing unit, wherein the method comprises: capturing M image frames of a first object by the image capturing unit in a first time period, wherein M is an integer larger than or equal to 2; determining a first region in the i-th image frame of the M image frames based on a first preset rule; obtaining M sub-image frames from the M image frames based on information of the first region, wherein the i-th sub-image frame of the M sub-image frames is determined based on the i-th image frame and the information of the first region; obtaining the j-th image frame of the M image frames, wherein j is the same as or different from i; and generating a first dynamic image of the first object by using the j-th image frame and the M sub-image frames.