The present disclosure provides a method for generating an HDR image. The method includes: providing an image sensor, in which the image sensor includes a pixel array and a filter array disposed on the pixel array, and each filter unit in the filter array covers a plurality of pixel units in the pixel array so as to constitute a pixel structure unit; and performing an exposure control to pixel units within each pixel structure unit respectively, in which a first part of the pixel units within each pixel structure unit are exposed for a first exposure time, a second part of the pixel units within the pixel structure unit are exposed for a second exposure time, and the first exposure time is greater than the second exposure time.