My computer monitor advertises a 1ms response time and the refresh rate is 144Hz. Wouldn’t that mean that the best response time possible is 1/144s?
In: 99
The latency from the refresh rate occurs on the graphics card, since that is where the frames are actually being rendered (at 144Hz, or more specifically the display buffer is encoded at 144Hz, it’s actually up to the software to set the contents of the frame buffer to the right thing.)
The monitor latency is how long that frame takes to be displayed once it is sent from the graphics card.
Basically, that 1ms is *on top* of the normal refresh latency.
There is a very big difference between throughput and latency.
Refresh rate depends on throughput – to get a 1000Hz refresh, you need 1000 complete frames a second. If you can only fit 144 a second onto the screen, it doesn’t matter how quickly the monitor can react – each new frame still needs to actually get there.
1ms just means that once the data is in the monitor, it only takes 1ms to use.
As an extreme example, take a typical CRT. The CRT has no memory whatsoever – it just scans the frame in a consistent pattern, and displays whatever color is on the wire at that exact moment. So the latency (response time) is essentially zero. But, it takes 1/60 of a second to finish the pattern, so it only does 60 fps.,
A monitor has three different speeds.
1) the speed it can process requests.
2) the speed it can paint images to the screen.
3) the speed at which it can erase the image in time for the next image.
Imagine your monitor is an etcha sketch. There is one person that (#1) that receives a new image. They translate it from a picture an image on paper into the controls to make it using the etcha-sketch knobs. “Turn left knob twice, while turning right knob once. Turn left knob once while turning right knob twice…. etc.” This process takes time.
These commands are passed to the knob turner. The knob turner turns the knob turn instructions really fast.
Finally, when the next image comes in, before you can display it, you need to shake the etcha-sketch to reset it to a blank display.
Computers and Calculators are very fast these days. Step #1 is insanely fast. It does have to run so fast that it could run at >1,000 hz. Step #2 is already very fast these days. Most modern LCDs are very quick at painting an image. It’s Step #3 that’s the real limitation. Once you’ve set an LCD pixel it takes a “while” for that image to fade.
Step #3 is actually a lot faster than older technologies. For instance CRT big tube TVs fired a photon at a glowing screen. The glow on really old TVs would last tens or even hundreds of milliseconds.
As to “best response time 1/144s” yes, that’s true assuming the HDMI cable can deliver 144 images per second. Your best case scenario is 1/144th of a second after being sent. But that best case scenario includes your monitor not adding much time to the equation. The total latency is: Input (mouse/keyboard press) time + Render Time (Time to create the image) + Transmit Time (1/144th of a second @ 144hz) + Display image emission time. It’s like the mailman saying “Look as soon as it arrives at the post office we’ll deliver it in less than 12 hours.” which could be true. But if the warehouse takes a few days to package it up, and then the shipping company takes 2 weeks to bring it to the post office, your total delivery time is more than “12 hours”. But that “12 hour” guarantee from the post office is still nice, vs it arriving and sitting in the post office for 2 days after it’s reached your town.
I think its 240hz and they use greyscales to simulate 4x the speed and call that fast enough to be able to say its “1000hz”
OP, try some LCD tests to learn more about the accuracy of displays.
https://www.eizo.be/monitor-test/
Start the test and you’ll see there’s 13 tests and #13 is Response time. As the blue and white box move, see how the vertical edges are ugly, they’re blurry & shadowy. I can’t explain the why’s about it, but you’ll actually see response time making issues. Maybe it’s along the lines of “ok a pixel responded in 1ms but it doesn’t show the right color quite yet, that takes some more ms”.
Try all the tests. #1 is good for seeing proportions, sharpness and more.
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