1. A method for generating an image that is performed at an image processing device, the method comprising: receiving a content; retinal scanning of a user's eye to estimate accommodation for the eye to permit a desired focus on a retina of the user's eye; calculating a focal depth based on the estimated accommodation, an eye lens of the user, and the retina of the user's eye; generating the image for the content according to the calculated focal depth; and outputting the generated image to permit receiving of the generated image by the user's eye.