A method for generating a translation image includes first and second lenses capturing first and second images toward an object respectively, an image processing device calculating a depth of field of a pixel in the first image relative to the first lens according to a first vertical viewing angle between the pixel in the first image and the first lens, a second vertical viewing angle between a corresponding pixel in the second image and the second lens, and a distance between the first and second lenses, the image processing device calculating a horizontal viewing angle between the pixel in the first image and the first lens according to the depth of field, coordinates of the pixel in the first image, and the distance, and the image processing device generating a translation image according to the coordinates of the pixel, the depth of field, the distance, and the horizontal viewing angle.