One of the first terms we all learned when facing current virtual reality devices is “screendoor effect” or curtain, and that seems to be the great workhorse of HTC and Oculus for their first commercial devices.
The curtain effect occurs when, after subjecting the HMD screen to a large magnification, the gaps between the pixels are observed, so that we have the feeling of looking at the image through a curtain. This would be, approximately, the simulated effect on an Oculus Rift DK1.
The Oculus Rift DK2, which can be considered the most advanced low-cost HMD available on the market, even being a developer version, improves this feeling a little, although it introduces other problems when using a Pentile matrix, the same as happens in Gear VR with the Galaxy Note 4. The pixels are getting smaller and smaller, but the effect is always there, although as the resolution increases it seems that it becomes less intrusive. However, Oculus has stated more than once that such an effect will not exist in the CV1, and there are many who claim that they do not perceive it in Crescent Bay. Now, a review of HTC Vive in the Vive Jam, confirms that in this viewfinder the black holes are also not appreciated. Given the resolution of the screens of these viewfinders (higher than Full HD in both cases, although Oculus has not yet revealed the exact figures), it seems very clear that both have used some kind of image diffuser that manages to disguise or eliminate the effect. In the case of HTC Vive, they claim that the image was very sharp and that no screendoor effect was perceived, although on a second thorough inspection, they came to notice it slightly on gray surfaces, while on white it was totally non-existent. Another good news was that they could not appreciate the subpixel pattern either, so it seems almost certain that HTC is not using Pentile matrices in Vive. So, it seems that the first commercial viewers for which months and not years are missing, will arrive free of curtains.