1. A method for processing an image, applicable to an electronic device including an image acquisition unit corresponding to an image acquisition area, wherein the method comprises: generating a first image and a second image according to an object to be acquired in the image acquisition area at a first instance of time, wherein both the first image and the second image are images corresponding to the object to be acquired, and an amount of data of the first image is larger than an amount of data of the second image; and storing the first image and the second image and setting the second image as an associated image of the first image; wherein generating the first image and the second image according to the object to be acquired in the image acquisition area at the first instance of time comprises: taking images respectively in a first imaging mode and a second imaging mode for the object to be acquired in the image acquisition area at the first instance of time to obtain the first image corresponding to the first imaging mode and the second image corresponding to the second imaging mode, wherein the first imaging mode is different from the second imaging mode; wherein taking images respectively in a first imaging mode and a second imaging mode for the object to be acquired in the image acquisition area at the first instance of time to obtain the first image corresponding to the first imaging mode and the second image corresponding to the second imaging mode comprises: taking an image of the object to be acquired by using a first number of sensing elements in the image acquisition unit to obtain the first image, and taking an image of the object to be acquired by using a second number of sensing elements in the image acquisition unit to obtain the second image, wherein the first number is larger than the second number; or taking an image of the object to be acquired in the image acquisition area at the first instance of time by using a first image acquisition unit with a first pixel to obtain the first image at a first resolution, and taking an image of the object to be acquired in the image acquisition area at the first instance of time by using a second image acquisition unit with a second pixel to obtain the second image at a second resolution, wherein the first resolution is higher than the second resolution.