I’ve added laptop screen response time testing to my laptop reviews, this post will help you understand what the values I am reporting mean.
I measure the center of the panel using the DET100A2 photodetector from Thorlabs with an Oscilloscope (PICOSCOPE 2204A) attached to a separate laptop. I am measuring 10% to 90% which is standard.
Laptop panels are tested while plugged into wall power with the screen set to the highest available refresh rate.
Screens are left on for at least 30 minutes to fully warm up prior to testing.
Response Time Table
Here’s the table I will be using to show response time:
It’s labelled 0-255 on the top and bottom, these are colour values. 0 is black, 255 is white, and in between are shades of grey. Response time will vary between the transition of the colours, so to gain an accurate picture it’s important to test multiple transitions between different colours.
The numbers within the table are millisecond values and represent rise and fall times.
The measurements on the upper right side display rise times (how long it takes to transition from a dark to light shade), while the bottom left side displays fall times (how long it takes to transition from a light to dark shade).
The green-yellow colours on the table above correspond to the following scale:
Basically, green = good, red = less good.
Each of the numbers on the table above are averages of 20 transitions. There are 30 data points in the table above, so the data in this table took 600 (30*20) total transitions to collect.
Response Time Values
Once we have all this data, we can use it to work out the average grey-to-grey (G2G) response time:
Here’s what each of these values means:
- Average G2G Response Time: This is simply an average of all the values in the first table. By taking the average from different transitions it is possible to get an accurate representation of the grey-to-grey response time.
- Lowest G2G Response Time: Many companies simply report the lowest transition as the response time, while this may be a little misleading, I note it here.
- Highest G2G Response Time: The opposite, the highest amount of time any transition took.
- Average Rise Time: This is the average of the numbers on the top right side only. It shows the average time taken to transition from a dark to light shade.
- Average Fall Time: This is the average of the numbers on the bottom left side only. It shows the average time taken to transition from a light to dark shade.
- ISO 13406-2 (0-255-0) Response Time: This is the time it takes to go from black, to white, then back to black. This value is obtained by simply adding these values together from the first graph, so in the example above, 4.69+5.46. This is the “Response Time Black To White” value that Notebook Check reports.
That’s it, this particular screen was from the Alienware m15 R2, so I would say it has an average response time of approximately 6.7ms, however other values are available too depending on how you want to slice and dice the data.