Is LCD response time realted to the maximum FPS the monitor can render or..?

[-Slacker-]

Ok so I read the LCD sticky thread (well, most of it), but it wasn't really what I was looking for - I already picked up from the name of the feature that it has to do with how big of a delay there is between the data being processed and and the moment it's displayed.

I'm still confused a bit though - I want to know if this is related to the FPS you're getting in applications (well.. mostly games) and if so, in what way.

At first I thought that the response time equates to the period between rendered frames (eg. 5ms response time means 200 FPS max), but that doesn't really make sense ... So how does it actually work?

 

[Ancalagon44]

Its in no way related to FPS. FPS is affected by your graphics card (ie how fast it can render the game) and your monitor's refresh rate, which is measured in Hertz (Hz). Most LCD monitors have a 60Hz refresh rate, some few have a 120 Hz refresh rate.

Response time, which can be measured in several ways, measures how long your LCD takes to respond to inputs. You could have a really high refresh rate and response time at the same time.

For instance, if your refresh rate was 120Hz, your response time was 200ms, and your game was rendering at 120FPs, then you would get 120FPS being displayed on your monitor, but it would take 200ms for anything you did in game to display on your screen. Hence refresh rate and response time, as far as I know, are independent of each other.

 

[-Slacker-]

Ah I see. Thanks for the quick reply :d

Well then here's another quick question: is there a noticeable difference between 5ms and 16ms?

 

[Daedalus685]

Response time is the time it takes for a pixel to change (respond to input). It is not an input lag. There is a lag for this transition to start, it is separate from the response time as during the response time the pixel is changing (it is often represented in black to white and back to black). The input lag is the time between the input and the start of responce, responce time is the time of the transition itself.

It is not related to FPS in that all frames are still sent (up to the 'refresh rate'). However, if the frame rate is causing a second frame to be drawn before the first finishes (the response time is too slow) the images will 'blur together' and one may see ghosting. Ghosting is when the old image and the new image exist at the same time for an instance (often very noticeable in high contrast games or while scrolling text).

 

[NoQuarter]

Response time isn't the same as input lag. Response time is the time it takes for a pixel to change color. Some shades will make the change quicker than the rated response time as well. If you had (in theory) really slow response time the next image would already be sent out before the pixels fully adjusted to the last image and you'd get a very motion blurred, ghosted image.

Input lag has to do with how long it takes for the LCD controller to get the input image sent out to the pixels. This is often around 20ms on a good monitor I believe. This is relative to a CRT which has 0ms input lag. This just determines how long it takes for the image to make it out the pipe and to your eyes.

Neither actually have anything to do with max displayable FPS, which is actually your more related to your refresh rate. The refresh rate is how often the LCD panel sends out a new image to the pixels. This is usually 60Hz (60 times a second). Even if your game is rendering at 200fps the display only updates 60 times a second so you either get 60 frames (with vsync) or a mash of 200 frames (each image displayed would be about 1/3 of 3 frames as the video card keeps updating the frame while the monitor updates the pixels).


So, the display pipeline looks like this:
Video card frame buffer pushed out to the monitor every 16.6ms (1/60th of a second, or 60Hz refresh rate), the monitor takes about 20ms to send this info to the pixels (input lag), the pixels take about 5ms to adjust to the new color (response time)