From the very beginning Varjo positioned itself as the winner of VR head-mounted displays megapixel race. Their “human-eye resolution” VR-1 truly shows more details than any other existing HMD.
However, due to fundamental physical limits, simply showing high resolution image is not enough for making the users see the best quality picture. With the physical size constraints, any HMD optical system is susceptible to aberrations which cause blur and color fringing no matter how crisp and clean the displayed picture is. Moreover, any movement of the eye pupil, which itself constitutes a lens element, makes the entire optical system quite different from the original optical design, resulting in blur and color fringing getting devastatingly strong. That effect forces the user to look straight at all times, not allowing eyeballs movement, which makes the visual experience limited and unnatural.
Almalence Digital Lens, a computational lens aberrations correction allows to overcome those limits by inversely pre-aberrating the image depending on eye tracking information. Needless to say, we were eager to check how that technology can improve picture clarity of the highest resolution HMD.
Note 1: This testing was performed by Almalence independently from Varjo. The Digital Lens test was implemented as a Unity application using public API.
Note 2: This is the very first testing, definitely showing sub-optimal results. We see a clear way to further improve the image clarity with the given headset.
We used a construction drawing as a test picture as it clearly demonstrates how the insufficient apparent resolution and clarity limit the VR usability.
To take the images within the HMD, we used our camera system with our eye imitator, allowing to capture what a human eye would see.
In the first example the eye looks about 10 degrees off the center. The left part of the gaze area falls onto the high resolution “focus display”, the right part falls onto the lower resolution “context display”
Move the slider left/right to see the difference. Left: Varjo VR-1 as is; Right: VR-1 with Digital Lens. Despite the high display pixel count, the picture does not look very clear. One can even start feeling sick when trying to read the numbers. The very same display with the Digital Lens delivers much clearer and readable picture.
In the next example the eye looks straight at the center, along the optical axis – the ideal case in which the HMD delivers its highest possible picture quality. The gaze area is completely over the focus display. Even in that case the Digital Lens shows a noticeable improvement:
Left: Varjo VR-1 as is; Right: VR-1 with the Digital Lens. Same display, but more legible text and crisper lines.
The beauty of the Digital Lens solution is that it is a pure computational technique, adding no extra size, weight or mechanical complexity to the device.
As mentioned above, those are very first tests, more to follow. However the tests already prove that the Digital Lens is an indispensable technology for high-end VR headsets, allowing to harness the full potential of high display pixel count and density.