OLED “microsecond response time” / “infinite contrast” claims vs reality?
Posted: 02 Sep 2021, 14:54
This post is about 2 related topics that have been bothering me for a while and I can’t find any good discussion online.
OLED panels have been touted as having sub-millisecond response times. What isn’t talked about as often is the fact that this only applies to G2G transitions. Black-to-gray (or black-to-anything) can take significantly longer (multiple refresh rate cycles), even in modern high-end panels seen on expensive smartphones and laptops, resulting in visible smearing in fast moving images on black backgrounds. The HTC Vive virtual reality headset will never show true black for this reason. Instead, “black” in the HTC Vive is just a very dark gray, similar to what you’d see on a “black” LCD. This brings me to my next point.
The biggest selling point of OLEDs is the fact that they are emissive displays, meaning each pixel produces its own light and each pixel can be individually turned off, allowing for black regions of the screen to be completely black (“infinite contrast”). However, in contexts where motion blur ideally needs to be minimal (such as fast paced gaming), true black must be avoided to prevent black smearing. So, the next important question is: how dark can the panel get without completely shutting off the pixels? The answer to this seems to generally be: not any darker than an LCD, as seen in the HTC Vive. (I have not been able to find many examples of this from different panels, so I may be wrong here. My HTC Vive’s black looks similar to a black LCD, and my iPhone 12 on minimum brightness with a darkest-gray image also looks similar to a black LCD.)
So: in contexts where motion blur must be small, the “infinite contrast” of OLED is reduced to roughly the same as LCD. OLED does retain the advantage of sub-millisecond G2G response time, though. So you can’t have your cake and eat it too; you have to decide between the two advantages of OLED — no ghosting, or true blacks.
Can anyone with more knowledge chime in on this topic? Have black smearing and/or minimum brightness been improved in any of the more recent OLED panels? Is it even theoretically possible to fix these issues completely? What physically causes these issues to begin with? Does microLED have these issues? I haven’t been able to find any good discussion about this.
OLED panels have been touted as having sub-millisecond response times. What isn’t talked about as often is the fact that this only applies to G2G transitions. Black-to-gray (or black-to-anything) can take significantly longer (multiple refresh rate cycles), even in modern high-end panels seen on expensive smartphones and laptops, resulting in visible smearing in fast moving images on black backgrounds. The HTC Vive virtual reality headset will never show true black for this reason. Instead, “black” in the HTC Vive is just a very dark gray, similar to what you’d see on a “black” LCD. This brings me to my next point.
The biggest selling point of OLEDs is the fact that they are emissive displays, meaning each pixel produces its own light and each pixel can be individually turned off, allowing for black regions of the screen to be completely black (“infinite contrast”). However, in contexts where motion blur ideally needs to be minimal (such as fast paced gaming), true black must be avoided to prevent black smearing. So, the next important question is: how dark can the panel get without completely shutting off the pixels? The answer to this seems to generally be: not any darker than an LCD, as seen in the HTC Vive. (I have not been able to find many examples of this from different panels, so I may be wrong here. My HTC Vive’s black looks similar to a black LCD, and my iPhone 12 on minimum brightness with a darkest-gray image also looks similar to a black LCD.)
So: in contexts where motion blur must be small, the “infinite contrast” of OLED is reduced to roughly the same as LCD. OLED does retain the advantage of sub-millisecond G2G response time, though. So you can’t have your cake and eat it too; you have to decide between the two advantages of OLED — no ghosting, or true blacks.
Can anyone with more knowledge chime in on this topic? Have black smearing and/or minimum brightness been improved in any of the more recent OLED panels? Is it even theoretically possible to fix these issues completely? What physically causes these issues to begin with? Does microLED have these issues? I haven’t been able to find any good discussion about this.
It's technically correct, which some claim is the best kind of correct, but still it doesn't tell the whole story.