SPD - A new VR resolution unit to end all PPI confusion

Hi, I see a lot of confusion on the forum when you try to compare the preceived resolution of the screens used in VR headsets.
PPI is good but only for display monitors, so I’m proposing a new measuring unit

SPD - Subpixels Per Degree

It takes into account the resolution of the screen, screen type (RGB or Pentile) and viewing angle.
The resulting value is the amount of physical sub-pixels visible in the angle of 1 degree (not in game rendered pixels)

Tell me what do you think.



Subpixels ? How did you calcuate this ? I think something is off.

Anyway the general term used is ‘pixels per degree’. https://www.roadtovr.com/understanding-pixel-density-retinal-resolution-and-why-its-important-for-vr-and-ar-headsets/

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RGB = 100% red + 100% green + 100% blue = 300%
Pentile = 50% red + 100% green + 50% blue = 200%


That’s why the new unit should also be calculated based on the sub-pixel arrangement as the difference between RGB and Pentile is quite significant 33%

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Hey Bro, where did you get Pimax 5K LCD ??? I though it was only OLED version ??? Does it exist ???

There is a lot of confusing info on the forum about Pimax 5K and no clear answer from the Pimax team, so I’ve decided to include both display options on the graph. I will update the graph as soon as Pimax gives some official specs.


Not sure how he calculated his values. But a review of psvr they did one of just sub pixels

Something like
Rgb 1920x1080x3 (psvr)
Pentile 2160x1200x2 (rift/vive)

The formula is on the bottom of the table in my second post. To calculate it properly you have to take per eye resolution, not a total of pixels of the panel.

The article i read was just explaining why psvr has virtually no sde when compared to rift/vive.

This article does not take into account the sub-pixel arrangement which is the reason why PSVR has better perceivable image quality. So again I would like to emphasize that my way of calculating the SPD is superior.

Of course there is another factor, the subpixel size (less black border around the subpixels). That’s why you can see the difference in the screendoor effect between Rift and Vive

Indeed though the Article was basic. It was good to demonstrate that rift/vive should have used rgb oled opposed to pentile oled displays.

For quality compare for sure spd would be more informative then basic ppd.