The OSD menu is controlled through a series of 6 touch-sensitive buttons located on the front edge of the lower bezel. They are marked by 6 small vertical grey strips, but they do not light up. There is also a touch-sensitive power on/off button located to the right of these as shown in the photo above and next to that is the power LED. This glows white during normal operation and amber in standby. You will notice on the left hand edge there is the human motion sensor and ambient light sensor as well.

Pressing any of the buttons brings up the quick access menu shown above, with each option aligned above the relevant button on the bottom of the screen display.

The input selection allows you to quickly switch between the 4 interfaces. The 'mode' menu gives you quick access to the preset mode menu.

The sound and brightness quick launch options are shown above and pop up a small scrolling bar for you to make quick and easy adjustments.

The 'ECO' menu contains all the Eco saving options including the Auto EcoView ambient light sensor and EcoView Sense human motion sensor. These are not listed within the main OSD so you need to access them via the quick launch if you want to turn them on or off.

The main OSD menu is accessed using the 'menu' option. Initially you are presented with 5 sections as shown above.

The first 'Color' section contains most of the options you will probably want to play with. You can change the preset mode, brightness, contrast, colour temperature and gamma modes here. There is a further 'advanced settings' sub-section which we will talk about below.

The 'advanced settings' sub-section contains the option for the pixel response time / overdrive setting as well as allowing you to adjust the RGB channels if you need to for calibration.

The signal menu contains a few options related to the video input. There are options for hardware aspect ratio control here, with 'full screen', 'aspect ratio' and 'dot by dot' (1:1 pixel mapping) options available.

The preferences section allows you to control a few things relating to the menu itself and also the power LED.

The languages and information sections are shown above. For the eagle-eyed, the information section photo is actually from the EV2450. It's the exact same thing on the EV2455 but the resolution would say 1920 x 1200.

All in all the menu navigation was quick and easy, and the software seemed responsive. It was pretty intuitive as well, although the software maybe looked a little dated and simplistic. There are enough options to play so no real complaints here.

Power Consumption

In terms of power consumption the manufacturer lists 13W typical usage, 49W maximum usage and <0.3W in standby. We carried out our normal tests to establish its power consumption ourselves.

We tested this ourselves and found that out of the box the screen used 23.1W at the default 100% brightness setting. This was once the ambient light sensor feature had been disabled. Maximum usage specified would presumably be with USB connected etc as well. Once calibrated the screen reached 12.5 W consumption, and in standby it used only 0.6W. Pretty much the same as the EV2450 really as to be expected given the similarities in hardware and features. We have plotted these results below compared with other screens we have tested:

Panel and Backlighting

Panel Part and Colour Depth

The Eizo EV2455 is built on an LG.Display LM240WUA-SSA1 AH-IPS panel which is capable of producing 16.7 million colours. We have not been able to verify via the panel spec sheet as to whether this is a true 8-bit module or a 6-bit + FRC panel, but we expect the latter given most of the current standard gamut IPS panels used today are 6-bit+FRC, especially in this size range. This is a measure commonly taken on modern IPS panels, and the FRC algorithm is very well implemented to the point that you'd be very hard pressed to tell any difference in practice compared with an 8-bit panel. The panel is confirmed when dismantling the screen and is the exact same panel used in the Dell U2415:

Screen Coating

The screen coating on the EV2455 is much like that featured on other recent IPS screens and the same as that on the EV2450, and the Dell U2415 of course which is using the same panel. It is a normal anti-glare (AG) offering as opposed to any kind of glossy coating. However, this is contrary to a lot of other older IPS based screens which usually feature a grainy and aggressive solution. Instead it is a light AG coating which retains its anti-glare properties to avoid unwanted reflections, but does not produce an overly grainy or dirty image. It's not a full semi-glossy appearance like some screens but it is nice and light. There was no sign of any cross-hatching patterns on the coating.

Backlight Type and Colour Gamut

The screen uses a White-LED (W-LED) backlight unit which has become very popular in today's market. This helps reduce power consumption compared with older CCFL backlight units and brings about some environmental benefits as well. The W-LED unit offers a standard colour gamut which is approximately equal to the sRGB colour space, and equating to ~72% NTSC. Anyone wanting to work with wider colour spaces would need to consider wide gamut CCFL screens, or perhaps the new range of GB-r-LED displays available.
 

Backlight Dimming and Flicker

We tested the screen to establish the methods used to control backlight dimming. Our in depth article talks in more details about a common method used for this which is called Pulse Width Modulation (PWM). This in itself gives cause for concern to some users who have experienced eye strain, headaches and other symptoms as a result of the flickering backlight caused by this technology. We use a photosensor +  oscilloscope system to measure backlight dimming control with a high level of accuracy and ease. These tests allow us to establish

1) Whether PWM is being used to control the backlight
2) The frequency and other characteristics at which this operates, if it is used
3) Whether a flicker may be introduced or potentially noticeable at certain settings

If PWM is used for backlight dimming, the higher the frequency, the less likely you are to see artefacts and flicker. The duty cycle (the time for which the backlight is on) is also important and the shorter the duty cycle, the more potential there is that you may see flicker. The other factor which can influence flicker is the amplitude of the PWM, measuring the difference in brightness output between the 'on' and 'off' states. Please remember that not every user would notice a flicker from a backlight using PWM, but it is something to be wary of. It is also a hard thing to quantify as it is very subjective when talking about whether a user may or may not experience the side effects.

100%                                                                   50%
 

10%

Above scale = 1 horizontal grid = 1ms

10% Zoomed

Above scale = 1 horizontal grid = 0.25ms

At 100% brightness a constant voltage is applied to the backlight as you would expect. As you reduce the brightness setting a Direct Current (DC) method is used for backlight dimming between settings of 100 and 20. From 20 downwards there is a very high frequency oscillation introduced, but it is not a full amplitude PWM on/off switching. This oscillation is of such a high frequency (18,000Hz) and such a low amplitude that it is unlikely to introduce issues for most users. Eizo refer to this backlight dimming technique as their "hybrid" system, although we were pleased that for brightness of 20 and below it was not the usual full PWM switching as we've seen on other EV models in the past. This was the same backlight control as we'd seen from the EV2450 16:9 aspect model.

For an up to date list of all flicker-free (PWM free) monitors please see our Flicker Free Monitor Database.

Contrast Stability and Brightness

The brightness control gave us a very good range of adjustment. At the top end the maximum luminance reached 321.47 cd/m² which was slightly higher even than the specified maximum brightness of 300 cd/m² by the manufacturer. There was a 320.79 cd/m² adjustment range in total, and so at the minimum setting you could reach down to an incredibly low luminance of 0.68 cd/m². We're not sure why it can go all this low as it's not really usable at that brightness, but basically Eizo have allowed a full range of the backlight here from on to off pretty much. This should be more than adequate for those wanting to work in darkened room conditions with low ambient light. A setting of ~33 in the OSD menu should return you a luminance of around 120 cd/m² at default settings.

We have plotted the luminance trend on the graph above. The screen behaves as it should in this regard, with a reduction in the luminance output of the screen controlled by the reduction in the OSD brightness setting. This was pretty much a linear relationship as you can see from the shape of the graph. It should be noted also that the brightness regulation is controlled by a Direct Current (DC) method instead of using Pulse Width Modulation for settings between 100 and 20. From 20 and below a very low amplitude, and very high frequency (18,000Hz) oscillation is introduced which should not cause any problems for most users. You can reach down to a luminance of around 76 cd/m² anyway before you even need to enter the zone where the oscillation is present.

The average contrast ratio of the screen was 892:1. It did fluctuate a bit across the brightness adjustment range. At the highest brightness settings the contrast was nearer to 850:1, while at the lower settings it reached over 950:1 in some cases. At the brightness settings you're more like to use day to day, the contrast ratio was stronger which was good news.

Testing Methodology

An important thing to consider for most users is how a screen will perform out of the box and with some basic manual adjustments. Since most users won't have access to hardware colorimeter tools, it is important to understand how the screen is going to perform in terms of colour accuracy for the average user.

I restored my graphics card to default settings and disabled any previously active ICC profiles and gamma corrections. The screen was tested at default factory settings using the DVI interface, and analysed using an X-rite i1 Pro Spectrophotometer (not to be confused with the i1 Display Pro colorimeter) combined with LaCie's Blue Eye Pro software suite. An X-rite i1 Display Pro colorimeter was also used to verify the black point and contrast ratio since the i1 Pro spectrophotometer is less reliable at the darker end.

Targets for these tests are as follows:

• CIE Diagram - validates the colour space covered by the monitors backlighting in a 2D view, with the black triangle representing the displays gamut, and other reference colour spaces shown for comparison

• Gamma - we aim for 2.2 which is the default for computer monitors

• Colour temperature / white point - we aim for 6500k which is the temperature of daylight

• Luminance - we aim for 120 cd/m², which is the recommended luminance for LCD monitors in normal lighting conditions

• Black depth - we aim for as low as possible to maximise shadow detail and to offer us the best contrast ratio

• Contrast ratio - we aim for as high as possible. Any dynamic contrast ratio controls are turned off here if present

• dE average / maximum - as low as possible. If DeltaE >3, the color displayed is significantly different from the theoretical one, meaning that the difference will be perceptible to the viewer. If DeltaE <2, LaCie considers the calibration a success; there remains a slight difference, but it is barely undetectable. If DeltaE < 1, the color fidelity is excellent.

Default Performance and Setup

Default settings of the screen were as follows. It should be noted that we disabled all EcoView settings where brightness of the screen is controlled based on ambient lighting conditions.

Eizo EV2455 - Default Factory Settings

 

 

Out of the box the screen looked good to the naked eye. Colours felt even and well balanced, and the only thing which felt off was the very bright backlight as brightness was maxed out at 100. We went ahead and measured the default state with the i1 Pro.

The CIE diagram on the left of the image confirms that the monitors colour gamut (black triangle) matches the sRGB colour space very well, with some slight over-coverage in blue and red shades. Default gamma was recorded at 2.2 average, leaving it with a very minor 1% deviance from the target of 2.2. White point was measured at 6392k leaving it a small 2% out from our target of 6500k which was very pleasing. This was very similar to what we'd seen from the EV2450 model as well.

Luminance was recorded at a very bright 325 cd/m² which is too high for prolonged general use. The screen was set at a default 100% brightness once you disabled the EcoView modes in the OSD menu but that is easy to change of course to reach a more comfortable setting. The black depth was 0.38 cd/m² at this default brightness setting, giving us a good (for an IPS panel) static contrast ratio of 846:1. Colour accuracy was very good too out of the box with a default dE average of 1.8, and maximum of 4.7. Testing the screen with various gradients showed smooth transitions with no sign of any banding thankfully. There was some very slight gradation evident in darker tones as you will see from most monitors and if you looked very closely you could pick out some twinkling from the Frame Rate Control. Not something you'd see in normal use though at all. Overall the default setup was very good and we were impressed. The contrast ratio was slightly lower than we had expected but it was still good for an IPS-type panel.

Calibration

We used the X-rite i1 Pro spectrophotometer combined with the LaCie Blue Eye Pro software package to achieve these results and reports. An X-rite i1 Display Pro colorimeter was used to validate the black depth and contrast ratios due to lower end limitations of the i1 Pro device.

Eizo EV2455 - Calibrated Settings

   

We stuck with the 'user1' preset mode in the OSD menu which allowed us access to the individual RGB channels. Adjustments were made during the process to the RGB channels as shown in the table above as well as the brightness control. This allowed us to obtain an optimum hardware starting point and setup before software level changes would be made at the graphics card level. We left the  LaCie software to calibrate to "max" brightness which would just retain the luminance of whatever brightness we'd set the screen to, and would not in any way try and alter the luminance at the graphics card level, which can reduce contrast ratio. These adjustments before profiling the screen would help preserve tonal values and limit banding issues. After this we let the software carry out the LUT adjustments and create an ICC profile.

Average gamma had been corrected more closely to the desired 2.2 average, correcting the minor 1% deviance we'd found out of the box which was good. The white point was adjusted to 6478k, correcting the minor 2% deviance we'd seen before as well. Luminance had also been improved thanks to the adjustment to the brightness control and was now being measured at 120 cd/m². This left us a black depth of 0.12 cd/m² and an excellent (for an IPS panel) static contrast ratio of 1032:1. Colour accuracy had been corrected nicely also, with dE average of 0.4 and maximum of 1.0. Although to be honest it was good out of the box anyway. LaCie would consider colour fidelity to be excellent.

Testing the screen with various colour gradients showed smooth transitions. There was some very slight gradation in darker tones but no banding was introduced which can often happen where adjustments are made to the graphics card LUT from the profilation of the screen. You can use our settings and try our calibrated ICC profile if you wish, which are available in our ICC profile database. Keep in mind that results will vary from one screen to another and from one computer / graphics card to another.

Calibration Performance Comparisons

The comparisons made in this section try to give you a better view of how each screen performs, particularly out of the box which is what is going to matter to most consumers. When comparing the default factory settings for each monitor it is important to take into account several measurement areas - gamma, white point and colour accuracy. There's no point having a low dE colour accuracy figure if the gamma curve is way off for instance. A good factory calibration requires all 3 to be well set up. We have deliberately not included luminance in this comparison since this is normally far too high by default on every screen. However, that is very easily controlled through the brightness setting (on most screens) and should not impact the other areas being measured anyway. It is easy enough to obtain a suitable luminance for your working conditions and individual preferences, but a reliable factory setup in gamma, white point and colour accuracy is important and not as easy to change accurately without a calibration tool.

From these comparisons we can also compare the calibrated colour accuracy, black depth and contrast ratio. After a calibration the gamma, white point and luminance should all be at their desired targets.

Default setup of the screen was very good overall, and should be perfectly fine for most users. There was only a very minor deviance in the desired gamma and white point, with a 1% and 2% error respectively which was very good. Colour accuracy was very good as well at 1.8 average dE. We can compare the EV2455 to the 16:9 format EV2450 as well, which had a very similar default setup.

Also comparing the EV2455 to its most logical competitor, the Dell U2415, the  Eizo had a slightly more accurate gamma by default and slightly better colour accuracy.

The panel did well in terms of black depth and contrast ratio for an IPS matrix once calibrated and when we'd switched to a lower brightness setting. It had a calibrated contrast ratio of 1032:1 measured. This couldn't compete with some of the VA based screens we've tested which could reach up to 2000 - 3000:1 static contrast ratios easily (e.g. BenQ BL3200PT, 2464:1). Some, like the Eizo Foris FG2421's MVA panel reached even higher up to 4845:1. For an IPS panel it was one of the best we have tested, out-performing some of the other strong IPS panel contrast ratios like the Dell U2415 (1011:1) for instance ever so slightly.

Viewing Angles

Above: Viewing angles shown from front and side, and  from above and below. Click for larger image

Viewing angles of the EV2455 were very good as you would expect from an IPS panel. Horizontally there was very little colour tone shift until wide angles past about 45�. A slight darkening of the image occurred horizontally from wider angles as you can see above as the contrast shifted slighting. Contrast shifts were slightly more noticeable in the vertical field but overall they were very good. The screen offered the wide viewing angles of IPS technology and was free from the restrictive fields of view of TN Film panels, especially in the vertical plane. It was also free of the off-centre contrast shift you see from VA panels and a lot of the quite obvious gamma and colour tone shift you see from some of the modern AMVA and PVA offerings. All as expected really from a modern IPS panel.

Above: View of an all black screen from the side. Click for larger version

On a black image there was a slight white glow from an angle which can be problematic on some IPS panels. If you are working in darkened room conditions and with dark content on the screen this may prove difficult. As you change your line of sight the white, silvery glow appears across the panel. This is not so much of a problem on a smaller 24" screen than it might be on some of the larger displays available today, but could still be distracting if you work with a lot of dark content. The IPS-glow was more pronounced than we had seen from the EV2450, which had impressed us with is "low glow" IPS panel. On the EV2455 it was pretty standard for an IPS panel. This was the same pattern we'd seen between the low glow Dell U2414H (16:9) and the normal glow U2415 (16:10 aspect).

Panel Uniformity

We wanted to test here how uniform the brightness was across the screen, as well as identify any leakage from the backlight in dark lighting conditions. Measurements of the luminance  were taken at 35 points across the panel on a pure white background. The measurements were taken using BasICColor's calibration software package, combined with an X-rite i1 Display Pro colorimeter with a central point on the screen calibrated to 120 cd/m². The below uniformity diagram shows the difference, as a percentage, between the measurement recorded at each point on the screen, as compared with the central reference point.

It is worth noting that panel uniformity can vary from one screen to another, and can depend on manufacturing lines, screen transport and other local factors. This is only a guide of the uniformity of the sample screen we have for review.
 

Uniformity of Luminance

The luminance uniformity of the screen was excellent overall. The very top left hand corner showed the only significant drop in luminance where it ranged down to 99 cd/m² as a minimum (-21.21%). The right hand edge was also a little darker than the rest of the screen but only by around 6 - 7%. Around 94% of the screen was within a 10% deviance from the centrally calibrated point which was very good.

Backlight Leakage

Above: All black screen in a darkened room. Click for larger version

As usual we also tested the screen with an all black image and in a darkened room. A camera was used to capture the result. Three was some slight clouding in the bottom left corner and along the right hand edge of the screen but nothing too severe at all, and certainly nothing you could spot during normal uses day to day.

General and Office Applications

The 1920 x 1200 resolution and 24.1" screen size give a nice decent area in which to work and the vertical resolution is a little more than the range of 16:9 aspect 24" models (1920 x 1080) out there in the market. A lot of people prefer this extra vertical area and it is useful for office applications we think. You may want to consider the fact that high resolution 27" 2560 x 1440 models are becoming increasingly available and so the difference in desktop size is certainly noticeable coming from a 27" screen like that. Nevertheless, the 24" 1920 x 1200 resolution should be adequate for many users. The screen offered a comfortable 0.27mm pixel pitch which delivered easy to read text at a nice size, in our opinion. The resolution is big enough for side by side split screen working as well in many cases although we do find that nowadays a lot of web content needs more than half a screen (i.e. wider than 960 pixels).

The ultra-thin bezel design is ideal for multi screen setups with a very small plastic border around the edge of the screen. You do need to account for the black panel border as well of course, but nevertheless the edges are very thin here and one of the key selling points.

The light AG coating of the new style AH-IPS panel is certainly welcome, and a very positive change from the older grainy and 'dirty' appearance of older IPS AG coatings. The wide viewing angles provided by the IPS panel technology on both horizontal and vertical planes, helps minimize on-screen colour shift when viewed from different angles. The default setup of the screen was very good in all areas, with only brightness needing to be turned down to something more comfortable (which doesn't affect other aspects of the setup). The contrast ratio was good out of the box for an IPS panel at 846:1 and actually even better when you lowered the brightness down to a more comfortable level. After calibration we had improved contrast ratio slightly more to 1032:1 which was excellent for an IPS panel.

The brightness range of the screen was also very good, with the ability to offer a luminance between 321 and 0.7 cd/m². This should mean the screen is perfectly useable in a wide variety of ambient light conditions, including darkened rooms. A setting of ~33 in the OSD brightness control should return you a luminance close to 120 cd/m² out of the box. On another positive note, the brightness regulation is controlled without the need for the use of the now infamous Pulse-Width Modulation (PWM), for settings between 100 and 20. From 20 and below a very low amplitude and very high frequency oscillation is introduced which is unlikely to cause many issues at all. You can reach a nice low luminance of around 76 cd/m² anyway before you even need to drop brightness below 20. Those who suffer from eye fatigue or headaches associated with flickering backlights need not worry.

There was no audible noise or buzzing from the screen, even when specifically looking for it using test images with a large amount of text at once. The screen also remains cool even during prolonged use. There is a 'paper' preset mode available from the menu which may be useful if you want to set up the screen for different uses perhaps and made the image far more yellow.

The screen offers 2x USB 3.0 ports which can be useful and it was nice to keep this up to date with the modern version. There are also some further extras including a useful ambient light sensor and human motion sensor. These are particularly useful in office environments and nice features we felt. The motion sensor is handy to switch the screen on and off when it detects you have left your desk, and the ambient light sensor can help you achieve comfortable brightness levels for varying ambient light conditions. The rival Dell U2415 didn't have these features so this was certainly a win for the Eizo model.

There are also some basic 2x 1W stereo speakers and associated audio input/output connections which might be useful to some people. They aren't up to much when it comes to gaming or movies, but should be fine for the odd mp3 or video clip. There was a decent range of ergonomic adjustments available from the stand allowing you to obtain a comfortable position for a wide variety of angles. The tilt function was pretty stiff and hard to operate though so could have been better. The VESA mounting support may also be useful to some people as well.

 
Above: photo of text at 1920 x 1200 (top) and 1680 x 1050 (bottom)

The screen is designed to run at its native resolution of 1920 x 1200 and at a 60Hz recommended refresh rate. However, if you want you are able to run the screen outside of this resolution. We tested the screen at a lower 1680 x 1050 resolution to see how the screen handles the interpolation of the resolution, while maintaining the same aspect ratio of 16:10. At native resolution the text was very sharp and comfortable as we've already discussed. When running at a 1680 x 1050 resolution the text is still pretty sharp, with low levels of blurring. You do lose some screen real-estate as well of course.

Responsiveness and Gaming

The EV2455 is rated by Eizo as having a 5 ms G2G response time and the panel uses overdrive / response time compensation (RTC) technology to boost pixel transitions across grey to grey changes. There is a user control over the overdrive impulse within the OSD menu in the advanced setting section of the 'color' menu, with options for off, standard and enhanced available to choose from. The part being used is the LG.Display LM240WUA-SSA1 AH-IPS panel. Have a read about response time in our specs section if you need additional information about this measurement.

We will first test the screen using our thorough response time testing method. This uses an oscilloscope and photosensor to measure the pixel response times across a series of 20 different transitions, in the full range from 0 (black) to 255 (white). This will give us a realistic view of how the monitor performs in real life, as opposed to being reliant only on a manufacturers spec. We can work out the response times for changing between many different shades, calculate the maximum, minimum and average grey to grey (G2G) response times, and provide an evaluation of any overshoot present on the monitor.

We use an ETC M526 oscilloscope for these measurements along with a custom photosensor device. Have a read of our response time measurement article for a full explanation of the testing methodology and reported data.

Response Time Setting Comparison (Overdrive option)

The EV2455 comes with a user control for the overdrive impulse available within the OSD menu in the advanced settings section of the 'color' menu as shown above. There are three options under the 'Overdrive' setting. First of all we carried out a smaller sample set of measurements in all three of the settings. These, along with various motion tests allowed us to quickly identify which was the optimum setting for this screen.

With the overdrive setting turned off, the pixel transitions were very slow overall. There was an average 15.3ms G2G response time measured which was slow and lead to noticeable blurring and ghosting of moving images. With overdrive turned off there was at least no overshoot at all here.

Pushing the overdrive setting up to 'Standard' brought about some obvious improvements. Response times were much better although a little slow in some transitions. The average G2G response time was now 9.5ms which was much better, although a little slower than some of the fastest IPS-type panels we've tested so far. There was a little overshoot introduced but not too much. This is certainly a better setting to use than overdrive 'off'.

With overdrive pushed up to the maximum setting of 'enhanced' the response times were improved again, this time an average of 7.3ms G2G was recorded. This would be very good for an IPS panel, had it not been for the massive amounts of overshoot introduced as a result. This lead to noticeable trailing and halos in moving images and so this mode should be avoided. Incidentally not even this mode lived up to the specified 5ms G2G response time which just goes to show you can't really trust some specs.

If we also carry out some subjective assessment of the screen during gaming and with the use of the PixPerAn moving car tests, we can also see the differences between each overdrive mode easily enough with the naked eye. With overdrive off there was a noticeable blur to the moving image as response times were slow. As you switch up to the 'standard' setting the blur is reduced nicely and the moving object becomes much sharper and clearer. There is still some blurring evident but no sign of any noticeable overshoot. When you switch up to the 'enhanced' overdrive mode the blurring is reduced a fraction more, but you can pick out some obvious overshoot in the test images, with both dark and light halos introduced to a very noticeable degree. This confirms the 'standard' mode is optimum on this screen.

More Detailed Measurements - Overdrive Standard

Having established that the overdrive 'standard' mode seemed to offer the best response/overshoot balance we carried out our normal wider range of measurements as shown below:

The average G2G response time was now more accurately measured at 9.6 ms. Fall times were on average slightly faster (9.2ms) than rise times (9.9ms) but overall the panel showed pretty consistent transitions times across the range. This was reasonable for an IPS panel really. It was ever so slightly faster than the EV2450 which had measured at 9.9ms G2G average.

If we evaluate the Response Time Compensation (RTC) overshoot then the results are pretty good but there are some transitions which show some moderate to high overshoot. A couple of the measured transitions showed some overshoot, mostly when changing between two very similar shades, more so if that transition was getting slightly lighter. Overall we were pretty pleased with the result from the EV2455 and showed that this overdrive setting was not being too aggressive with the overdrive impulse. It should be noted that the overshoot was slightly higher than on the EV2450 model.

Transition: 0-50-0 (scale = 20ms)

As an example, the 0-50-0 transition is shown above where you can see the largest recorded overshoot (28.0%) on the rise time.

We have written an in depth article about input lag and the various measurement techniques which are used to evaluate this aspect of a display. It's important to first of all understand the different methods available and also what this lag means to you as an end-user.

Input Lag vs. Display Lag vs. Signal Processing

To avoid confusion with different terminology we will refer to this section of our reviews as just "lag" from now on, as there are a few different aspects to consider, and different interpretations of the term "input lag". We will consider the following points here as much as possible. The overall "display lag" is the first, that being the delay between the image being shown on the TFT display and that being shown on a CRT. This is what many people will know as input lag and originally was the measure made to explain why the image is a little behind when using a CRT. The older stopwatch based methods were the common way to measure this in the past, but through advanced studies have been shown to be quite inaccurate. As a result, more advanced tools like SMTT provide a method to measure that delay between a TFT and CRT while removing the inaccuracies of older stopwatch methods.

In reality that lag / delay is caused by a combination of two things - the signal processing delay caused by the TFT electronics / scaler, and the response time of the pixels themselves. Most "input lag" measurements over the years have always been based on the overall display lag (signal processing + response time) and indeed the SMTT tool is based on this visual difference between a CRT and TFT and so measures the overall display lag. In practice the signal processing is the element which gives the feel of lag to the user, and the response time of course can impact blurring, and overall image quality in moving scenes. As people become more aware of lag as a possible issue, we are of course keen to try and understand the split between the two as much as possible to give a complete picture.

The signal processing element within that is quite hard to identify without extremely high end equipment and very complicated methods. In fact the studies by Thomas Thiemann which really kicked this whole thing off were based on equipment worth >100,1000 Euro, requiring extremely high bandwidths and very complicated methods to trigger the correct behaviour and accurately measure the signal processing on its own. Other techniques which are being used since are not conducted by Thomas (he is a freelance writer) or based on this equipment or technique, and may also be subject to other errors or inaccuracies based on our conversations with him since. It's very hard as a result to produce a technique which will measure just the signal processing on its own unfortunately. Many measurement techniques are also not explained and so it is important to try and get a picture from various sources if possible to make an informed judgement about a display overall.

For our tests we will continue to use the SMTT tool to measure the overall "display lag". From there we can use our oscilloscope system to measure the response time across a wide range of grey to grey (G2G) transitions as recorded in our response time tests. Since SMTT will not include the full response time within its measurements, after speaking with Thomas further about the situation we will subtract half of the average G2G response time from the total display lag. This should allow us to give a good estimation of how much of the overall lag is attributable to the signal processing element on its own.

Lag Classification

To help in this section we will also introduce a broader classification system for these results to help categorise each screen as one of the following levels:

• Class 1) Less than 16ms / 1 frame lag - should be fine for gamers, even at high levels

• Class 2) A lag of 16 - 32ms / One to two frames - moderate lag but should be fine for many gamers. Caution advised for serious gaming and FPS

• Class 3) A lag of more than 32ms / more than 2 frames - Some noticeable lag in daily usage, not suitable for high end gaming