Traditionally, rendering has focused on “photorealism”: simulating images from cameras with minimal aberration. But rendering for virtual reality should emphasize “perceptual realism” to enable immersion in the virtual environment. To this end, we shouldn’t neglect the imperfect optics of the human eye. We introduce a rendering method that incorporates natural aberrations and thereby produces retinal images that are much closer to what people normally experience. We first calculate the retinal image that would be produced by a 3d scene given an appropriate eye model. Our model incorporates two universal optical effects: defocus and chromatic aberration. The calculated image is the target retinal image. We then solve an inverse problem to determine We then solve an inverse problem to determine what image to put on a display screen that, what image to put on a display screen that, when viewed by an eye, will produce the same image on the retina as the target. We call this algorithm ChromaBlur. Here is the target retinal image for a 3d scene and its depth map for a horizontal cross-section. Focus distance is just over 2 diopters. With Conventional rendering, this is the displayed image associated with that scene and focus distance. With ChromaBlur, this is the displayed image. The right panels show the differences for red, and blue between the target retinal image and the retinal images produced by Conventional and ChromaBlur rendering. Gray represents no difference. As focus distance is changed, displayed images are updated accordingly. ChromaBlur produces much more accurate results than conventional rendering. We investigated whether ChromaBlur rendering drives accommodation, that is, whether it guides the eye’s focus. Stimuli were projected onto a screen. And viewed by one of the subject’s eyes. A focus-adjustable lens and aperture were just in front of that eye. Accommodation of the other eye was measured with an autorefractor. There were three conditions. In the Real Change condition, optical distance was changed by manipulating the power of the adjustable lens. In the Conventional condition, simulated distance was changed by altering blur with conventional rendering. In the ChromaBlur condition, the simulated distance was changed again in rendering but now with it color correct. The power of the adjustable lens was not changed during Conventional and ChromaBlur trials. Here’s an example trial and response. The stimulus is initially at 0 diopters, and accommodation is accordingly at 0. The stimulus then jumps to 1.4 diopters. A third of a second later, the eye accommodates to roughly that distance, a very typical response. Here are the results in all 3 conditions. The first panel shows focusing responses to Real Changes in optical distance. They are accurate and consistent. The second panel shows responses to changes in defocus only (that is, to conventional rendering). The eye does not accommodate, which means that conventional rendering does not drive focusing responses. The third panel shows responses to changes in defocus plus chromatic aberration (that is, ChromaBlur rendering). Remarkably, the eye accommodates much like it does to real changes. ChromaBlur drives focusing responses quite effectively! We showed in another experiment that the response to ChromaBlur persists for stimulus durations of several seconds. We also showed that ChromaBlur continues to drive accommodation effectively when the display resolution is equal to or worse than current HMDs. We also investigated whether ChromaBlur increases the impression of real depth. Images of complex 3d scenes were viewed by the left eye. They were rendered Conventionally, with ChromaBlur, or with Reverse ChromaBlur (which is a reversal of natural chromatic aberration). Subjects saw two stimuli on each trial and indicated which yielded a greater depth impression. ChromaBlur stimuli yielded consistently greater impressions of depth than Conventional. ChromaBlur stimuli also yielded consistently greater depth impressions than Reverse ChromaBlur. Reverse ChromaBlur and Conventional yielded roughly equivalent impressions. Thus, ChromaBlur rendering enhances the impression of depth. ChromaBlur opens an opportunity for next-generation displays. One can couple ChromaBlur rendering with focus-adjustable lenses and eye tracking. When the viewer fixates a new distance in the virtual scene, the tracker senses it. This triggers rendering for the new focus distance. By using ChromaBlur, we assure that accommodation will occur quickly in the right direction. The fixation change also triggers adjustment of the lenses in front of the eyes so that the lens inside the eye will adjust just as it would in the natural environment. Recreating the natural relationship between accommodation and blur would also restore the natural relationship between accommodation and vergence, thereby eliminating the vergence-accommodation conflict and the various issues associated with that conflict. Our ChromaBlur rendering technique creates displayed images that, when viewed by the human eye, create more realistic retinal images. This allows greater perceptual realism, which, in turn, should enable more comfortable, immersive, and engaging experiences in virtual environments.