Our test method is based on the X-Rite i1 Display Pro colorimeter and an X-Rite i1 Basic Pro spectrophotometer, which we can use to calibrate the colorimeter for every monitor test. Using a 3D printed accessory, we can use this colorimeter to measure the viewing angles of even the larger screens. For the analysis of the data we use our own workflow developed in SpectraCal Calman 5.
We still measure monitors ‘out of the box,’ but if they have an sRGB-mode we test this separately. This is also the case with an AdobeRGB-mode. An exception to this are the monitors that are clearly adjusted for a wider colour space out of the box – in this case we measure using a corresponding colour space. The standard one we use is the sRGB-triangle.
We test monitors after setting them to a brightness of 150 cd/m² (or a value that comes as close to this as possible). That brightness is representative for what you will use in most scenarios in a normally lit room and most of the current screens can display this brightness. By setting all the screens to the same brightness, we are evening out the playing field. We also still measure the maximum brightness and contrast in relation to the power usage. Below you can read a brief description of every test.
Brightness and contrast
We measure brightness and contrast in both 150 cd/m² and the maximum brightness, as well as the black values in both settings. We also measure the minimum brightness (fully turned down in the menu) in white areas of a picture. Aside from that, we measure the contrast between a white and black surface, surrounded by a 50% grey surface (transvers measurement), the checkerboard contrast in a 5x3 pattern and the maximum contrast between a fully white and fully black surface.
While measuring the uniformity, first we look at the relationship between the lowest brightness in a white surface compared to highest brightness expressed as a percentage. For example: the least bright part of the screen was 77% of the brightness of the brightest part. In the new test we do not only measure this relationship, but also that between the average and the highest brightness. Aside from that we perform the uniformity measurement with a black surface as well, showing severe clouding and backlight bleeding – if it is present. All uniformity measurements result in five screenshots per tested monitor: the uniformity of black, white, the contrast ratio at all (15) points, the colour temperature uniformity and the relative colour differences in comparison with the middle, expressed as DeltaE-value.
We measure brightness and the colour changes in comparison with the middle of the screen, at an angle of 45 degrees and present them as a DeltaE-value. This is based on the average of red, green, blue, cyan, magenta and yellow, plus 100% and 75% white. Because we also calculate the default deviation of these measurements, we can give an indication of whether or not there is a colour shift: a high sd means that one or more measurements deviates a lot resulting in a colour shift.
As another part of this test we use a screenshot to show the deviation of grey relative to the middle from each of the measured corners. We do this for every tested product as this allows any colour shift to become clear.
This result is now based on a large amount of measurements, the so-called ‘Colour checker’ where we look at a lot of common hues. Once again, we show the default deviation as well as the average deviation, to give an impression of the amount of fluctuation of our measurements. A smaller number means there is a more constant degree of deviation. This is also the case for our grayscale measurements, which are performed in twenty steps, resulting in more accurate data. With every tested product we will also add a screenshot of a so-called saturation sweep in order to show the deviation of the base- and support colours in the entire colour space. Of course, we will also publish the screenshots of the colour measurement and colour checker results.
The measurements are not only done at 100% brightness (white, black, standby on and off), but also for white and black screen at 150 cd/m² as this presents a more realistic comparison in real life conditions.
In the gaming test, we measure response times and input lag. For this we still use a photo sensor with an oscilloscope and a combination of a Leo Bodnar input lag tester as well as a comparison with a CRT-monitor.
This test procedure generates large quantities of data. For now, we have chosen to add and show this data in its entirety via our database. As a direct result, our pages with the test results of monitors have become a lot longer. We have tried to keep it as clear as possible by showing the data in specific order. The reaction times and input lag will be shown first, followed by the power consumption. After that you will find a small block with the basic results of brightness and contrast, followed by a larger block with the uniformity results. Next up are the viewing angle values and following that are the colour measurements in the default view. If the monitor has an sRGB-mode, an identical block will follow with the results of the measurements using that mode; the same will be done for a possible AdobeRGB-mode.
In the graphs on the following page, the 24" monitors are represented by blue lines and the 27" monitors have green lines.